SUPPORTED BY. Nestlé Nutrition Institute Logotype October Print Pantone 280 C Pantone 354

Transcription

1 P A R I S Nestlé Nutrition Institute Logotype October 2011 Print Pantone 280 C Pantone 354 Print CMYK Blue = C 100% / M 72% / B 18% Green = C 80% / Y 90% SUPPORTED BY Print Monochrome Pantone 280 C 100% + 45%

2 Preface The booklet in front of you is the summary of the 15th Sport Nutrition conference. For this conference we visited Paris, allowing us to welcome the cyclists on the Avenue des Champs-Élysées after finishing the Tour de France. Celebrating this 100th edition of the Tour de France we had chosen the theme Sport nutrition in the Tour de France for this meeting. We were successful in setting a stage where upon leading scientists shared their insights with a select group of sports nutritionists, sports dieticians, physiologists, coaches, and athletes. The format of these conferences has been highly successful and this is due to the unique formula that we use. In short, we bring together a relatively small audience consisting of leading sports nutrition professionals, a small number of elite speakers, journalists, and a few elite athletes and coaches. The carefully selected speakers are not only academically well established but also have a background in sport and do not only deliver excellent scientific presentations but can translate the science to something of practical use. By combining this with a number of hot topics in sports nutrition, and sufficient time to interact, we create some great discussions. Therefore, we have introduced workshops to further bridge the gap between science and practice. The main theme of this and all previous conferences: translating the often complicated science into a practical message that is of immediate use to an athlete or coach. This aim of this booklet is to provide a short overview of the science and a number of practical guidelines illustrated with figures and tables. These conferences, the summary booklet you have in front of you, the DVDs and a web site with information are an important step in closing the existing gap between biomedical science and sports practice. We hope the information provided will be of use. I want to thank Zibi Szlufcik and Jessica Marsch for all the hard work in putting this together and making it all possible. Also, I would like to express my sincere gratitude to PowerBar and the Nestle Nutrition Institute. Without their help and support the conference and we would not have been able to produce these and other materials. Luc van Loon Maastricht University Content Preface Luc van Loon Dietary protein needs in endurance cyclists Naomi M. Cermak and Luc J.C. van Loon Novel ergogenics in competitive cycling and long distance running John A. Hawley Dietary strategies to maintain proper hydration for endurance athletes in the heat Ron Maughan Optimizing exogenous fuelling during Tour de France Dr. Trent Stellingwerff Strategies to minimize central fatigue during endurance exercise in the heat Romain Meeusen Dietary protein and short-term muscle disuse Luc J.C. van Loon Nutrition for post-exercise recovery a review of current opinion Louise M Burke

3 1 Dietary protein needs in endurance cyclists Naomi M. Cermak and Luc J.C. van Loon Maastricht University Introduction Dietary protein plays a key role in facilitating the skeletal muscle adaptive response to resistance as well as endurance type exercise training, thereby modulating muscle reconditioning. A single bout of exercise stimulates both muscle protein synthesis and, to a lesser extent, muscle protein breakdown. However, post-exercise protein balance will remain negative in the absence of food intake. Dietary protein ingestion stimulates skeletal muscle protein synthesis, inhibits protein breakdown and, as such, stimulates muscle protein accretion following both resistance (9, 13, 20, 21) as well as endurance (8, 14) type exercise. This will lead to a greater skeletal muscle adaptive response to each successive exercise bout, resulting in more effective muscle reconditioning. Despite limited evidence, some basic guidelines can be defined regarding the preferred amount, source, and timing of dietary protein that should be ingested to allow proper muscle reconditioning during endurance type exercise training. Amount of dietary protein Though it has been well established that dietary protein ingestion effectively stimulates muscle protein synthesis rates both at rest and following exercise, there is no information available on the amount of dietary protein that should be ingested to maximize muscle protein synthesis rates following a bout of endurance type exercise. Moore et al. (15) reported that muscle protein synthesis rates increase with the ingestion of greater amounts of protein, reaching maximal stimulation after ingesting 20 g (egg) protein in young males after performing a bout of resistance type exercise. The authors speculated that athletes should ingest this amount of dietary protein 5-6 times daily to maximize skeletal muscle protein accretion. Whether this would also provide an optimal dietary strategy to maximize muscle protein synthesis rates following endurance type exercise remains to be established. Source of dietary protein Various studies have reported improvements in post-exercise protein balance and/or greater muscle protein synthesis rates following the ingestion of whey protein (19), casein protein (19), soy protein (22), casein protein hydrolysate (12, 13), egg protein (15), and whole-milk and/or fat-free milk (7, 22). To date few studies have directly compared the post-exercise muscle protein synthetic responses to the ingestion of different types of protein. Milk protein and its main isolated constituents, whey and casein, offer an anabolic advantage over soy protein (18, 22). Furthermore, whey protein seems to induce a greater muscle protein synthetic response when compared with casein (18). The differences in the muscle protein synthetic response to the ingestion of various protein sources can be attributed to differences in protein digestion and absorption kinetics (10, 19) as well as amino acid composition (16, 18). Carbohydrate co-ingestion In the endurance trained athlete, rapid restoration of depleted muscle glycogen stores is generally a priority following completion of a single bout of exercise. As a consequence, endurance trained athletes generally focus on carbohydrate ingestion to accelerate post-exercise recovery. Co-ingestion of small amounts of protein can accelerate muscle glycogen repletion when less than optimum amounts of carbohydrate (<1.0 g/kg bodyweight/h) are ingested during the first few hours of post-exercise recovery (1, 3). Ingestion of carbohydrate during post-exercise recovery inhibits the exercise induced increase in muscle protein breakdown. Therefore, resistance athletes often ingest a combination of protein plus carbohydrate during recovery from exercise (ie weight-gainers ). However, co-ingesting carbohydrate does not further increase post-exercise muscle protein synthesis rates when ample protein is already ingested (9). Though carbohydrate co-ingestion is not required to maximize post-exercise muscle protein synthesis rates, it is likely that a little carbohydrate will attenuate the post-exercise rise in muscle protein breakdown rate, thereby improving protein balance (5). Timing of dietary protein ingestion The timing of protein ingestion represents another important factor stimulating post-exercise muscle protein anabolism. A more direct provision of dietary protein following cessation of exercise has been shown to result in a more positive protein balance, when compared to protein provided several hours after exercise (14). Furthermore, recent studies suggest that carbohydrate and protein co-ingestion prior to and/or during prolonged endurance type exercise may further augment post-exercise muscle protein accretion (2, 4, 21). The latter has been attributed to a more rapid supply of amino acids to the muscle during the acute stages of post-exercise recovery. However, protein ingestion prior to and/ or during exercise already stimulates muscle protein synthesis during exercise, thereby creating an extended timeframe 3

4 for muscle protein synthesis rates to be elevated (2, 4, 11). This may be of particular relevance to the (ultra)endurance athlete who spends several hours per day exercising continuously (11). Recent work shows that the impact of exercise on stimulating post-prandial muscle protein synthesis is maintained up to at least 24 hours after the last exercise bout (6). This seems to be in line with recent observations that protein ingestion prior to sleep stimulates muscle protein synthesis during overnight recovery, allowing muscle reconditioning to occur during sleep (17). Research is warranted to assess the impact of dietary protein distribution throughout the day as a means to promote post-exercise reconditioning and improve endurance type exercise training efficiency (1). Conclusion Protein ingestion during and after endurance type exercise facilitates the skeletal muscle adaptive response to each successive exercise bout, thereby improving muscle tissue reconditioning. Whey protein is most effective in stimulating acute post-exercise muscle protein synthesis. Ingestion of g dietary protein during or immediately after an exercise bout maximizes post-exercise muscle protein synthesis rates. Co-ingestion of a large amount of carbohydrate does not further augment post-exercise muscle protein accretion, but is required when aiming to accelerate post-exercise muscle and liver glycogen repletion. Dietary protein ingestion prior to sleep allows muscle protein synthesis rates to increase during overnight recovery from exercise, which may improve endurance training efficiency. Figure 1 Dose reponse relationship between the amount of protein ingested and post-exercise muscle protein synthesis rates. Values represent means±sem. Means with different letters are significantly different from each other. Figure redrawn from Moore et al., Am J Clin Nutr, 2009; 89; , American Society for Nutrition. Figure 2 Dietary protein ingestion prior to sleep stimulates post-exercise overnight recovery. Fractional synthesis rate (FSR) of mixed muscle protein during overnight recovery following ingestion of water or protein prior to sleep. Values represent means±sem. *significantly different from water (P=0.05). Figure redrawn from Res et al., Medicine & Science in Sports & Exercise, Publish Ahead of Print: DOI: /MSS.0b013e31824cc363. Figure 3 Nutritional recommendations to support muscle reconditioning following exercise. 4

5 References 1. Beelen M, Burke LM, Gibala MJ, and van Loon LJ. Nutritional strategies to promote postexercise recovery. Int J Sport Nutr Exerc Metab 20: , Beelen M, Koopman R, Gijsen AP, Vandereyt H, Kies AK, Kuipers H, Saris WH, and van Loon LJ. Protein coingestion stimulates muscle protein synthesis during resistance-type exercise. Am J Physiol Endocrinol Metab 295: E70-77, Beelen M, Kranenburg JV, Senden JM, Kuipers H, and van Loon LJ. Impact of caffeine and protein on post-exercise muscle glycogen synthesis. Med Sci Sports Exerc 44: , Beelen M, Zorenc A, Pennings B, Senden JM, Kuipers H, and van Loon LJ. Impact of protein coingestion on muscle protein synthesis during continuous endurance type exercise. Am J Physiol Endocrinol Metab 300: E , Borsheim E, Cree MG, Tipton KD, Elliott TA, Aarsland A, and Wolfe RR. Effect of carbohydrate intake on net muscle protein synthesis during recovery from resistance exercise. J Appl Physiol 96: , Burd NA, West DW, Moore DR, Atherton PJ, Staples AW, Prior T, Tang JE, Rennie MJ, Baker SK, and Phillips SM. Enhanced amino acid sensitivity of myofibrillar protein synthesis persists for up to 24 h after resistance exercise in young men. J Nutr 141: , Elliot TA, Cree MG, Sanford AP, Wolfe RR, and Tipton KD. Milk ingestion stimulates net muscle protein synthesis following resistance exercise. Med Sci Sports Exerc 38: , Howarth KR, Moreau NA, Phillips SM, and Gibala MJ. Coingestion of protein with carbohydrate during recovery from endurance exercise stimulates skeletal muscle protein synthesis in humans. J Appl Physiol 106: , Koopman R, Beelen M, Stellingwerff T, Pennings B, Saris WH, Kies AK, Kuipers H, and van Loon LJ. Coingestion of carbohydrate with protein does not further augment postexercise muscle protein synthesis. Am J Physiol Endocrinol Metab 293: E , Koopman R, Crombach N, Gijsen AP, Walrand S, Fauquant J, Kies AK, Lemosquet S, Saris WH, Boirie Y, and van Loon LJ. Ingestion of a protein hydrolysate is accompanied by an accelerated in vivo digestion and absorption rate when compared with its intact protein. Am J Clin Nutr 90: , Koopman R, Pannemans DL, Jeukendrup AE, Gijsen AP, Senden JM, Halliday D, Saris WH, van Loon LJ, and Wagenmakers AJ. Combined ingestion of protein and carbohydrate improves protein balance during ultra-endurance exercise. Am J Physiol Endocrinol Metab 287: E , Koopman R, Verdijk L, Manders RJ, Gijsen AP, Gorselink M, Pijpers E, Wagenmakers AJ, and van Loon LJ. Co-ingestion of protein and leucine stimulates muscle protein synthesis rates to the same extent in young and elderly lean men. Am J Clin Nutr 84: , Koopman R, Wagenmakers AJ, Manders RJ, Zorenc AH, Senden JM, Gorselink M, Keizer HA, and van Loon LJ. Combined ingestion of protein and free leucine with carbohydrate increases postexercise muscle protein synthesis in vivo in male subjects. Am J Physiol Endocrinol Metab 288: E , Levenhagen DK, Gresham JD, Carlson MG, Maron DJ, Borel MJ, and Flakoll PJ. Postexercise nutrient intake timing in humans is critical to recovery of leg glucose and protein homeostasis. Am J Physiol Endocrinol Metab 280: E , Moore DR, Robinson MJ, Fry JL, Tang JE, Glover EI, Wilkinson SB, Prior T, Tarnopolsky MA, and Phillips SM. Ingested protein dose response of muscle and albumin protein synthesis after resistance exercise in young men. Am J Clin Nutr 89: , Pennings B, Boirie Y, Senden JM, Gijsen AP, Kuipers H, and van Loon LJ. Whey protein stimulates postprandial muscle protein accretion more effectively than do casein and casein hydrolysate in older men. Am J Clin Nutr 93: , Res PT, Groen B, Pennings B, Beelen M, Wallis GA, Gijsen AP, Senden JM, and van Loon LJ. Protein ingestion prior to sleep improves post-exercise overnight recovery. Med Sci Sports Exerc Tang JE, Moore DR, Kujbida GW, Tarnopolsky MA, and Phillips SM. Ingestion of whey hydrolysate, casein, or soy protein isolate: effects on mixed muscle protein synthesis at rest and following resistance exercise in young men. J Appl Physiol 107: , Tipton KD, Elliott TA, Cree MG, Wolf SE, Sanford AP, and Wolfe RR. Ingestion of casein and whey proteins result in muscle anabolism after resistance exercise. Med Sci Sports Exerc 36: , Tipton KD, Ferrando AA, Phillips SM, Doyle D, Jr., and Wolfe RR. Postexercise net protein synthesis in human muscle from orally administered amino acids. Am J Physiol 276: E , Tipton KD, Rasmussen BB, Miller SL, Wolf SE, Owens-Stovall SK, Petrini BE, and Wolfe RR. Timing of amino acid-carbohydrate ingestion alters anabolic response of muscle to resistance exercise. Am J Physiol Endocrinol Metab 281: E , Wilkinson SB, Tarnopolsky MA, Macdonald MJ, Macdonald JR, Armstrong D, and Phillips SM. Consumption of fluid skim milk promotes greater muscle protein accretion after resistance exercise than does consumption of an isonitrogenous and isoenergetic soy-protein beverage. Am J Clin Nutr 85: ,

6 2 Novel ergogenics in competitive cycling and long distance running John A. Hawley RMIT University, Melbourne Abstract Athletes are continually striving to improve training capacity and performance. Not surprisingly, widespread use of a large number of nutritional supplements is commonplace in most sports as athletes search for a magic bullet that will elevate their performances to a higher level. Some of these so-called nutritionals have undergone rigorous scientific scrutiny and have shown to be ergogenic (i.e., work enhancing) while others, despite widespread anecdotal claims and athlete testimonials lack credible evidence for a performance benefit. Ergogenics that improve endurance cycling and running performance include the nutrient-exercise strategy of carbohydrate loading, carbohydrate mouth-rinsing, caffeine intake and the ingestion of various forms of carbohydrate-containing foods and drinks during exercise. Other nutritionals (such as dietary nitrate, β-alanine, L-arginine and some antioxidants) that perturb physiological homeostasis and showed initial promise of performance enhancement have, in some cases, failed to live up to early expectations. Introduction and Background There are many products that are potentially ergogenic for aerobic-based exercise (i.e., endurance running, road and time-trial cycling and triathlon). However, despite widespread and often grossly exaggerated claims for many of these so-called nutritional ergogenics, evidence-based support for the overwhelming majority of products is lacking. Ergogenics that improve endurance performance include the dietary practice of carbohydrate loading, carbohydrate mouth-rinsing strategies before and during an event, caffeine intake and the ingestion of various forms of carbohydrate-containing foods and drinks during exercise. Caffeine and carbohydrate loading have the most evidence-based support of being both ergogenic and safe, while recent work has focused on the use of a combination of ergogenics in an effort to determine whether there are synergistic effects on performance. Carbohydrate-loading While by no means a novel nutritional ergogenic, carbohydrate loading (or glycogen supercompensation ) remains the foundation of nutritional preparation for optimal performance in endurance sports and, to a large extent, should underpin all other race day nutritional practices. The dietary-exercise protocols recommended for carbohydrate loading and the subsequent effects on metabolism and exercise capacity have been reviewed elsewhere (Hawley et al. 1997). Glycogen supercompensation improves endurance performance (in which a set distance is covered as quickly as possible) by 2 to 3% (Hawley et al. 1977). Carbohydrate mouth rinse: Something for nothing? Carter et al. (2004) were the first to report that 1 hr cycle time-trial performance in well trained cyclists was enhanced when subjects rinsed their mouths with a 6.4% maltodextrin carbohydrate solution compared to when water was rinsed. Since that study, most, but not all investigations have reported that carbohydrate mouth rinse is ergogenic for endurance performance (none have reported any negative effects). Difference between study results has likely due to the nutritional status of the subjects prior to intervention: mouth rinse improved performance to a greater extent when subjects commenced an exercise performance task in a fasted rather than fed state. Accordingly, we recently investigated the effect of a carbohydrate mouth rinse on a 60 min simulated cycling time-trial performance commenced under both these nutritional conditions (Lane et al. 2013). 12 competitive male cyclists each completed four experimental trials: two were commenced 2 h after a meal (containing 2.5 g/kg body mass of carbohydate) and two after an overnight fast. Carbohydrate mouth rinse (a 10% maltodextrin rinsed for 10 sec then immediately expectorated) improved performance to a greater extent in a fasted compared with a fed state; however, optimal performance was achieved in a fed state with the addition of a carbohydrate mouth rinse. Carbohydrate feedings during exercise: Multiple transportable carbohydrates Increasing exogenous carbohydrate availability via oral carbohydrate ingestion has long been known to be ergogenic for endurance events. Based largely on the results from studies conducted in the 1990 s (reviewed in Hawley et al and Jeukendrup and Jentjens 2000), it was widely accepted that rates of exogenous carbohydrate oxidation from a variety of different carbohydrate sources could not exceed 1.0 g/min. Accordingly, it was recommended that for sporting events lasting longer than 60 min, athletes develop a personalized nutrition plan that combined carbohydrate intake of g /h and adequate rehydration with the practical opportunities for intake during the event or session (Coyle, 2004). Of note is that competitive athletes report much higher (~90 g/h) intakes of carbohydrate during exercise (Kimber, Ross, Mason, 6

7 & Speedy 2002) raising the intriguing possibility that the current guidelines for carbohydrate ingestion during endurance events are inappropriate. A series of studies from the Jeukendrup laboratory suggest this may well be the case. In several independent but related investigations, Jeukendrup and colleagues systematically measured the rates of oxidation of various sources, forms, and combinations of carbohydrate consumed during submaximal laboratory cycling exercise (reviewed in Jeukendrup 2010). When a beverage composed of a single source of carbohydrate (i.e., glucose) was ingested, the maximum rate of exogenous carbohydrate oxidation was indeed ~1 g/min, as previously reported (Hawley et al and Jeukendrup and Jentjens 2000). However, their most important finding was that when glucose was consumed in combination with a carbohydrate that is absorbed by a different transport mechanism (e.g. fructose, using the GLUT5 transporter), rates of ingested carbohydrate oxidation greatly exceeded 1.0 g/min (Jentjens and Jeukendrup 2005). Indeed, when glucose and fructose were co-ingested in a 2:1 ratio, rates of ingested carbohydrate oxidation reached ~1.8 g/ min (Jeukendrup, 2010). While all the lab studies reporting such high rates of ingested carbohydrate ingestion have been undertaken with moderately trained subjects typically cycling at low (~60-65% of VO 2max ) intensities, there appears to be a reasonable association between athletic performance in the field and the rate of exogenous carbohydrate ingestion (i.e., the more carbohydrate you ingest, the superior the performance) suggesting that most of the ingested carbohydrate is being oxidized by the working muscles. Recent evidence of a dose response relationship between carbohydrate intake and performance of events longer than 2.5 h in which the optimal rate of intake appears to be within the range of g/hr support this notion (Smith et al., 2013). Athletic practice has both preceded and now benefited from these findings, since sports nutrition companies now produce a range of carbohydrate-containing fluids/gels/bars with this ratio of the so-called multiple transportable carbohydrates. A variety of forms of these products, ranging from liquid to solid, appear to deliver high rates of carbohydrate (Pfeiffer et al. 2010) and can be tolerated in the field (Pfeiffer et al. 2011). Beetroot juice: The new magic bullet? A series of studies from the Jones laboratory in the U.K. showed that dietary nitrate supplementation (i.e., beetroot juice) reduce the O 2 cost of submaximal exercise and improved high-intensity exercise tolerance. In these and other experiments, subjects typically ingested a concentrated from of beetroot juice (0.5 L containing ~ 5-7 mmol of nitrate) in the 2-3 hr before an exercise bout. Using double-blind, crossover designs and well trained subjects, acute dietary nitrate supplementation improved cycling economy (i.e., elicited a higher power output for the same O2 cost) and enhanced both 4 and 16.1-km cycling time-trial performance (e.g., Lansley et al. 2011). While these early studies revealed promising results (i.e., dietary nitrate supplementation improved short time-trial performance by 1-3 % in club-level cyclists), it was not known whether these ergogenic effects persisted in longer endurance events or if dietary nitrate supplementation could enhance performance to the same extent in better trained individuals. This proved not to be the case! Recently the same group using a similar dietary supplementation protocol found that acute dietary supplementation with beetroot juice did not improve 50 mile TT performance in well-trained cyclists (Wilkerson et al. 2012). Accordingly, the jury is still deciding whether beetroot juice is ergogenic for endurance running and cycling. Caffeine: An old magic bullet While athletes continue to search for novel ergogenics to improve athletic performance, it is widely accepted that caffeine provides a consistent, tried and trusted means to enhance endurance running and cycling events (for review see McNaughton et al. 2008). Contemporary protocols for caffeine ingestion on the day of a competition are based on recent evidence that low doses of caffeine (3 mg/kg body mass) are equally as effective as the traditionally used larger doses (i.e., 6-9 mg/kg body mass) and that caffeinated gums can also provide a measured and rapidly absorbed caffeine dose to improve performance capacity (Ryan et al. 2013). Combining the old and the new: The Cocktail effect Many ergogenic aids elicit their performance enhancing effect via different and independent mechanisms. Accordingly, it may be that the performance enhancement attained by each separate ergogenic may be cumulative if they were coingested (the so-called cocktail effect ). We (Lane et al. Unpublished Observations) have recently tested this hypothesis and examined the single and combined effects of beetroot juice and caffeine supplementation under optimal nutritional conditions (i.e., a pre-event meal, carbohydrate ingestion as well as regular oral carbohydrate mouth rinse during exercise). 24 competitive cyclists (12 males, 12 females) each completed 4 experimental trials commenced after caffeine gum ingestion (CAFF; 3 mg/kg body mass), concentrated beetroot juice (BJ; ~10 mmol of NO 3- ), caffeine plus beetroot juice (CAFF+BJ) or a control (CONT). Under all conditions subjects completed a simulated London Olympic cycling time trial course (Females km, Males km). 7

8 Figure 1. Mean power output combined for males and females; CAFF+BJ (beetroot juice with caffeine); CAFF (caffeine); BJ (beetroot juice); CONT (placebo of caffeine and beetroot juice); * Different to CONT and BJ (P < 0.01); Values are mean ± SD. As shown in Figure 1, Power output was significantly enhanced after CAFF+BJ and CAFF (3.4% and 3.0% respectively, P < 0.01) compared to CONT. However, there was no effect of beetroot juice supplementation when used in either isolation (-0.4%, P = 0.6; vs. to CONT) or when combined with caffeine ingestion (-0.9%, P = 0.4; compared CAFF). Our findings suggest that caffeine (3 mg/kg body mass) administered in the form a caffeinated gum prior to competition can increase cycling power output by ~3-4% in both males and females. Meanwhile, beetroot juice supplementation used in a cycling time trial lasting approximately min did not enhance performance. Summary and Practical Recommendations Athletes who wish to enhance endurance running and cycling competition performance should use a variety of novel race day supplements and products in combination with older traditional nutritional regimens that include: 1. Carbohydrate loading A high (~10 g/kg body mass) carbohydrate intake in the hr prior to competition combined with an exercise taper (reduction in training volume) 2. Carbohydrate mouth rinse Rinsing the mouth (but not swallowing) a 6-10 g/100 ml concentration carbohydrate solution during the warm up to a competition 3. Caffeine intake Ingesting 3 mg/kg of caffeine in the hour prior to a major competition. If the events duration exceeds 3 hr, then a further dose (3 mg/kg) should be taken after 150 mins 4. Carbohydrate ingestion during exercise Athletes should develop personalized carbohydrate intake plans that provide up to 90 g of multi-transportable carbohydrates for each hour of competition 8

9 References 5. Carter JM, Jeukendrup AE, Jones DA. The effect of carbohydrate mouth rinse on 1-h cycle time trial performance. Med Sci Sports Exerc 2004; 36(12): Coyle, E. F. Fluid and fuel intake during exercise. J Sports Sci 2004; 22: Currell, K. and Jeukendrup, A. E Superior endurance performance with ingestion of multiple transportable carbohydrates. Med Sci Sports Exerc 40: Hawley, J.A., Dennis, S.C., Noakes, T.D. Oxidation of carbohydrate ingested during prolonged endurance exercise. Sports Med 1992; 14(1): Hawley JA, Schabort EJ, Noakes TD, Dennis SC. Carbohydrate-loading and exercise performance. An update. Sports Med (2): Hodgson AB, Randell RK, Jeukendrup AE. The metabolic and performance effects of caffeine compared to coffee during endurance exercise. PLoS One 2013;8(4):e Jentjens RL, Jeukendrup AE. High rates of exogenous carbohydrate oxidation from a mixture of glucose and fructose ingested during prolonged cycling exercise. Br J Nutr 2005; 93(4): Jeukendrup AE. Carbohydrate and exercise performance: the role of multiple transportable carbohydrates. Curr Opin Clin Nutr Metab Care, 2010; 13(4): Jeukendrup AE, Jentjens R. Oxidation of carbohydrate feedings during prolonged exercise: current thoughts, guidelines and directions for future research. Sports Med 2000; 29(6): Kimber NE, Ross JJ, Mason SL, Speedy DB. Energy balance during an ironman triathlon in male and female triathletes. Int J Sport Nutr Exerc Metab 2002; 12(1): Lane SC, Bird SR, Burke LM, Hawley JA. Effect of a carbohydrate mouth rinse on simulated cycling time-trial performance commenced in a fed or fasted state. Appl Physiol Nutr Metab 2013; 38(2): Lansley KE, Winyard PG, Bailey SJ, Vanhatalo A, Wilkerson DP, Blackwell JR, Gilchrist M, Benjamin N, Jones AM. Acute dietary nitrate supplementation improves cycling time trial performance. Med Sci Sports Exerc 2011; 43(6): McNaughton LR, Lovell RJ, Siegler J, Midgley AW, Moore L, Bentley DJ. The effects of caffeine ingestion on time trial cycling performance. Int J Sports Physiol Perform 2008; 3(2): Smith JW, Pascoe DD, Passe DH, Ruby BC, Stewart LK, Baker LB, Zachwieja JJ. Curvilinear dose-response relationship of carbohydrate (0-120 g h(-1)) and performance. Med Sci Sports Exerc 2013; 45(2): Pfeiffer B, Stellingwerff T, Zaltas E, Jeukendrup AE. CHO oxidation from a CHO gel compared with a drink during exercise. Med Sci Sports Exerc 2010; 42(11): Pfeiffer B, Stellingwerff T, Zaltas E, Hodgson AB, Jeukendrup AE. Carbohydrate oxidation from a drink during running compared with cycling exercise. Med Sci Sports Exerc 2011; 43(2): Ryan EJ, Kim CH, Fickes EJ, Williamson M, Muller MD, Barkley JE, Gunstad J, Glickman EL. Caffeine gum and cycling performance: a timing study. J Strength Cond Res 2013; 27(1): Triplett, D., Doyle, J. A., Rupp, J. C. and Benardot, D An isocaloric glucose-fructose beverage s effect on simulated 100-km cycling performance compared with a glucoseonly beverage. Int J Sport Nutr Exerc Metab 20: Wilkerson DP, Hayward GM, Bailey SJ, Vanhatalo A, Blackwell JR, Jones AM. Influence of acute dietary nitrate supplementation on 50 mile time trial performance in welltrained cyclists. Eur J Appl Physiol 2012; 112(12):

10 3 Dietary strategies to maintain proper hydration for endurance athletes in the heat Ron Maughan Loughborough University Dehydration if it is sufficiently severe will impair all aspects of physiological function and has a negative effect on both physical and mental performance. Dehydration occurs when the rate of water ingestion is less than the rate of water losses from the body. Athletes should therefore be aware of the factors that affect water loss and of the magnitude of these losses in different situations. At rest in a comfortable environment, water needs may be less than 1 litre per day, but during hard exercise in a warm and humid environment, sweat rates may reach 2 litres per hour. A few individuals are capable of sweat rates that are even higher than this. At such high sweat rates, other sources of water loss (primarily respiratory, transcutaneous and urinary) become relatively insignificant. In the absence of fluid intake, this sweating rate translates to a loss of 1-2% of body mass per hour. There is much debate as to the point at which dehydration may begin to adversely affect performance, but the evidence suggests that a body water deficit of about 2% of initial body mass is likely to lead to reduced endurance performance in a warm environment. Some individuals may be able to tolerate greater losses, but some are likely to be affected at even smaller water deficits. These individual variations in both rates of water loss and tolerance to dehydration mean that individualised assessment of athletes and development of personal hydration plans are essential. Table 1 gives some examples of how athletes can calculate the effects of their sweat losses and drink intakes: all that is needed is a measurement of body weight before and after exercise and a record of how much drink was consumed. The latter can be assessed by weighing drinks bottles using kitchen scales or using bottles of known volume. Pre-exercise body mass (kg) a Post-exercise body mass (kg) a Total body mass oss or gain (g) d Drinks consumed during exercise ( g or ml) b Urine excreted during exercise ( g or ml) c Sweat volume (ml) 60 min run h walk h cycle Hydration status (%) d a body mass measured nude with dry skin b drinks consumed any time between the two body mass measurements c urine emptied from the bladder any time between the two body mass measurements d + = water gain, - = water loss, 0 = no change in water balance An individualised hydration strategy should be developed for both training and competition and it should take account of fluid needs before, during and after training or competition. The performance effects of dehydration have usually been assessed in subjects who have begun exercise well hydrated, but it is likely that many athletes are dehydrated to some extent when they begin training and some may also be dehydrated when they begin competition. Some may think that adding the stress of hypohydration to that of training may enhance adaptations to training and may increase the tolerance to dehydration. The limited available evidence suggests that dehydration will not be effective in this regard, but is likely to reduce the quality of training and to increase the level of stress experienced during training. Where possible, therefore, it seems sensible to ensure that training begins in a well-hydrated state. The best indication of a positive hydration state is probably that the kidneys are producing a large volume of dilute urine. The aim should not be to drink so much that there is a need for frequent urination, but rather to ensure that the urine produced in the hours before training is pale in colour. Cyclists are accustomed to drinking in training, but most distance runners are not because of the simple practicalities of access to drinks. Runners should, however, ensure that there are some opportunities to practise drinking in training: this is necessary to practise the skill of drinking while running, to become accustomed to the sensation of running with fluid in the gut, and to learn how much fluid is tolerable and what kind of drinks are most effective. Drinks should supply carbohydrate fuel, and perhaps also some electrolytes (sodium), so experimentation is essential. To make this possible, some long training runs can consist of repeated laps of 2-3 km, with a coach/friend/family member pressed into acting as drinks provided each lap. The aim of fluid intake during exercise should be to support optimum performance. It should generally be part of a planned strategy that is based on an understanding of the target fluid intake. Drinking only when thirsty may be appropriate for some individuals, but substantial fluid deficits may be incurred in the early stages of competition without the athlete feeling the need to drink. A planned strategy allows for an even distribution of intake across the race and should provide 10

11 reassurance that an appropriate amount is being consumed. It should never be necessary to drink so much that an increase in body weight occurs. As in so many aspects of training and competition, there is an element of trial and error before that athlete finds a strategy that best meets their needs. Effective rehydration after heavy sweat losses requires replacement of the electrolytes lost in sweat as well as the water lost, and rehydration will not occur unless both are replaced. The rehydration strategy should be integrated with other elements of the recovery strategy: intake of carbohydrate and some protein are usually priorities. If the foods eaten in the first few hours of recovery do not contain salt, this should be supplied from drinks: most commercial sports drinks contain some salt, but higher levels may be necessary is salt losses are high. Post-exercise rehydration should be seen as part of the preparation for the next competition or training session. Practical messages Although athletes often look to support staff to inform them of what they should do, there are several simple steps that they can take themselves to identify whether their current hydration practice is appropriate to their needs. 1. Athletes should be encouraged to weigh themselves before and after training sessions of different durations and intensities and in different weather conditions to estimate their sweat losses. Weight loss should generally not exceed about 1-2% of body mass. If more than this has been lost, then they probably did not drink enough and should drink more next time. If body mass loss was less than this, fluid intake was probably greater than was necessary for hydration purposes. 2. Any athlete who is passing urine less often than normal may be dehydrated. If urine volume is small and urine colour becomes darker, fluid intake should be increased. The aim should NOT be for urine to be as pale as possible. 3. Salty sweaters may need drinks with more salt and may need more salt in food when sweat losses are high. The use of salt tablets is seldom, if ever, warranted. Self-assessment of salt losses can be done by wearing a black T-shirt and looking for salt stains. High salt losses are a contributing factor in some, but certainly not all, cases of muscle cramp. 11

12 4 Optimizing exogenous fuelling during Tour de France Dr. Trent Stellingwerff, PhD Canadian Sports Institute Grand tour cycling events, such as the Tour de France, feature some of the most extreme physical demands of any endurance sport, with cyclists expending between 6,000 and 9,000 kcals per stage. Given the reality that most athletes only have ~2,000 kcals of muscle glycogen, and spend 4 to 6 hours per stage cycling, maximizing the amount of energy and carbohydrate (CHO) they can deliver to their muscles is fundamentally important not only for that days performance, but for subsequent days as well. Contrary to popular belief, both heart rate and wattage meter data show that grand tour cycling is not overly intense, with average heart rates of ~135 beats per minute [1] and wattages of 220 to 235W [2]. Interestingly, these exercise intensity values are very similar to the level of exercise intensity utilized in many laboratory studies examining the impact of exogenous (oral) carbohydrate supplementation on either exogenous CHO oxidation (CHO oxid ) or performance, thus making these studies findings highly relevant for optimizing performance in grand tour cycling events (for reviews see: [3, 4]). Furthermore, changes in the last several years to the World Anti-Doping Association (WADA) Prohibited List now prevents teams and doctors from administering any recovery infusions or injections (CHO, fluids etc.) of greater than 50ml per 6h period, which adds further importance in optimizing energy intake throughout the stages and in the short pre and post-stage periods. This short review will examine both the laboratory and field research and outline contemporary recommendations on maximizing CHO oxidation and hydration during prolonged endurance sports, such as Grand Tour cycling events. Proposed Mechanism for Performance Enhancement The exact mechanism(s) of fatigue, and thus what limits performance, are multi-factorial in nature. Furthermore, the impact that carbohydrate (CHO) supplementation can have on metabolism and performance depends on the length and intensity of the exercise as well as the dose (intake rate) and type of carbohydrate. Thus, the mechanisms and regulation involved with fuel metabolism and energy production during exercise are very complex. However, there have been two major mechanisms that have emerged to primarily explain why CHO supplementation improves performance, and these are: 1) a stimulation of the central nervous system (CNS) by CHO when muscle and liver glycogen energy stores are not limiting via oral exposure and 2) direct contribution of CHO energy and CHOoxid during situations of low-glycogen availability. The former generally occurs during exercise durations of less than 1 hour, while the latter generally occurs during exercise situations of greater than 2h, and would certainly be the major mechanism responsible for any performance, or recovery, benefits during grand tour cycling events. Although there are many factors to prolonged endurance exercise fatigue (>2h), beyond just fuel provision to the muscle, the primary mechanism(s) for this improved performance has been an enhanced maintenance of plasma glucose (prevention of hypoglycemia), which results in augmented CHO oxid by the muscles during exercise. However, the question remains: can more carbohydrate, and hence, greater CHO oxid further improve performance? It appears that the rate limiting step to CHO oxid is at the level of the GI tract due to the intestinal CHO transport mechanisms; specifically the activity of the SGLT 1 transporter for glucose and the GLUT-5 transporter for fructose [3]. It is thought that having a high uptake and oxidation efficiency of supplemented CHO beverages should reduce the accumulation of CHO in the gastrointestinal (GI) tract and in turn reduce the potential for GI distress during exercise [4]. This point is not trivial as that even minor GI distress is associated with negative endurance performance outcomes. Laboratory Evidence for CHO Intake to Improve Endurance Performance In support of this, several recent laboratory studies evaluated the combined ingestion of a sports drink containing glucose + fructose or maltodextrin + fructose in a 2:1 ratio (multi-transportable CHO s) and at an ingestion rate of ~1.8 g/ min on oxidation rate of exogenous CHO (for review see: [5]). This pattern of multi-transportable CHO ingestion resulted in ~20 to 50% higher CHO oxid compared with the ingestion of a drink containing an isocaloric amount of glucose or maltodextrin only, and this leads to an ~8% increase in prolonged endurance performance [6]. Figure 1 outlines 38 different studies examining the effects of CHO supplementation on performance outcomes as compared to a placebo (usually artificially sweetened water) over varying exercise times. Nearly every single study demonstrates a performance benefit of CHO intake, with the effect on performance ever increasing with prolonged exercise time (r=0.356; p<0.01). Further, the impact that multi-transportable CHO s have on performance when exercise was longer than 2h was a 9.6±4.8% increase in performance, compared to only 4.3±2.7% increase with single-source CHO s (subset, Figure 1). 12

13 Figure 1. Overview of all laboratory performance studies (n=38) examining CHO intake and exercise performance versus a non-caloric placebo, showing a significant correlation between an ever increasing performance effect versus total exercise time. Further, multi-transportable CHO s resulting in double the performance outcome compared to single-source CHO when exercise duration is greater than 2h (subset figure). In support of this, a recent 51 subject CHO dose-response study using a cycling intervention showed a curvilinear performance response, with a 4.7% improvement in time-trial performance at a CHO intake rate of 78 g CHO/hr as the best outcome [7]. However, there was large individual variability in the optimal intake, as the 95% confidence intervals suggested uncertainty in the optimum of ~68-88 g CHO/hr (Figure 3). Practical Field Recommendations Indirect correlative data also supports the notion that the more CHO an athlete can tolerate, the better their endurance performance during prolonged exercise, as demonstred in figure 2 (data from [8]). Figure 2 Significant correlation (r=-0.55; p<0.001) between self-selected CHO intake rate and finishing time at Ironman Hawaii (data from [8]). Recent evidence suggests that these intestinal CHO transporters appear to be trainable, so athletes who repeatedly expose their transporters to high CHO intakes can potentially up-regulate CHO oxid [9]. Conversely, we have previously found a highly significant correlation between endurance athletes who have a history of GI problems during exercise and measured GI problems during competition[8], with about 15 to 20% of endurance athletes having a chronic history of GI problems. Taken together, it appears that there is a large diversity of CHO oxid and GI responses, and that each endurance athlete will have a unique sweet spot where they are able to absorb and oxidize a maximum amount of CHO oxid /fluids to improve endurance performance versus too much fluids and CHO, which will cause GI distress and decrease performance. This individual variability is reflected in a recently published elite-marathon nutrition and training case study, showing a self-selected range from 49 to 77g CHO/hr in 3 elite marathoners during sub 2:12 marathon efforts. Summary figure 3 includes a very wide range of recommended CHO intake, depending on the type, the individual and the mode and intensity of the exercise intervention. This wide range of CHO intake recommendations probably best reflects the wide ranges actually found, and well-tolerated, in the field with athletes [8, 10]. Therefore, it is imperative that athletes practice and develop an individualized fuelling and hydration plan prior to any competitions, which can be tracked and monitored into a tracking sheet (Table 1). 13

14 Table 1. Example of an individualized fuelling and hydration tracking sheet. Practical fuelling and hydration recommendations during exercise include: On every session longer than ~75min track sweat rate in different weather conditions, especially in targeted race weather conditions track information into worksheet. Practice fuelling and hydration in every long run. Practice with different amounts of fluids and fuels, mimicking the timing of intake in your race (~15 to 20min) -- track information into worksheet. Ideally practice under race pace intensities! Aim for at least 40g of carbs/h and >500ml/h water to start. But try and really test your GI and see what you can handle. The more you can adapt and handle taking in carbohydrate, the more fuel you will have at the end of the race. Ideally, you can adapt to hit >60g CHO/h or more when running and >90g CHO/h cycling. Figure 3 Schematic overview of key recommendations for CHO intake rate, CHO type and form over varying exercise durations and intensities. References 1. Fernandez-Garcia, B., et al., Intensity of exercise during road race pro-cycling competition. Medicine and science in sports and exercise, (5): p Vogt, S., et al., Power Output during the Tour de France. International journal of sports medicine, (9): p Jeukendrup, Carbohydrate and exercise performance: the role of multiple transportable carbohydrates. Current opinion in clinical nutrition and metabolic care, (4): p Jeukendrup, Carbohydrate intake during exercise and performance. Nutrition (7-8): p Jeukendrup, A.E., Carbohydrate feeding during exercise. European Journal of sport Science, (2): p Currell, K. and A.E. Jeukendrup, Superior endurance performance with ingestion of multiple transportable carbohydrates. Medicine and Science in Sports and Exercise, (2): p Smith, J.W., et al., Curvilinear Dose-Response Relationship of Carbohydrate (0-120 g.h-1) and Performance. Medicine and science in sports and exercise, (2): p Pfeiffer, B., et al., Nutritional intake and gastrointestinal problems during competitive endurance events. Medicine and science in sports and exercise, (2): p Cox, G.R., et al., Daily training with high carbohydrate availability increases exogenous carbohydrate oxidation during endurance cycling. Journal of Applied Physiology, (1): p Stellingwerff, T., Case study: nutrition and training periodization in three elite marathon runners. International journal of sport nutrition and exercise metabolism, (5): p

15 5 Strategies to minimize central fatigue during endurance exercise in the heat Romain Meeusen Vrije Universiteit Brussel Exercise in the heat, especially if there is high humidity, can negatively affect performance. During exercise several mechanisms occur to lose the metabolic heat that is produced by muscle contraction. For heat loss to occur, excess heat should be transported from the core to the skin where heat can be lost to the environment. The rate of heat transfer from core to skin is determined by the temperature gradient between these two. When the metabolic heat is eventually transported to the skin, heat loss is greatly accelerated by vasodilation and sweating. Thermoregulation and hydration. Several studies showed that voluntary exhaustion is reached at a specific core temperature. This cut-off temperature is individually different, but can be between 39.5 C and 41 C. This happens even if the individuals start exercising at different core temperatures, being it pre-cooled or already pre-heated [1]. It is therefore important to use specific methods to prevent the premature attainment of this critical core temperature. Body water deficits will often degrade aerobic exercise performance. In the majority of studies performed on exercise in the heat it was shown that exercise performance decreased with levels of dehydration of 2% body mass loss, and this reduction in exercise capacity was further accentuated when combined with heat stress [4]. In addition, as the level of dehydration increases, aerobic exercise performance is degraded proportionally and the magnitude of performance decrement is likely related to environmental temperature and exercise task. High skin temperature in combination with dehydration has a high impact on the impairment of submaximal aerobic exercise performance [4]. It is also well established that dehydration impairs cognition [5], eventually leading to coma and death. It seems that in healthy humans, relatively modest levels of dehydration can affect the brain and degrade cognitive function. Adverse effects of dehydration on cognition appear to first become detectable at a level of approximately 1.5% body weight loss. Changes in mood, such as increased fatigue seem to be the first indication that dehydration is affecting brain function [5]. In addition, it demonstrates that moderate heat stress impairs coping behavior, as well as working and reference memory [5]. Coping strategies when exercising in the heat. Several strategies (e.g. heat acclimatization, rehydration, pre-cooling, ) have proven to be particularly effective in reducing performance decrements associated with exercise in the heat. It seems that keeping well hydrated and optimizing carbohydrate levels are the most important strategies when exercising in the heat. Precooling is a popular strategy to combat the negative effects of heat stress induced fatigue. Several external and internal methods such as cold air exposure, cold water exposure (e.g. cooling vests), cold water immersion, cryotherapy (ice applications, such as ice towels, or iced garments) have all been used in the recent years. The purpose is to reduce core temperature before exercise, most of these methods are effective in improving performance in the heat. Internal cooling through the ingestion of cold fluids and ice has gained considerable attention as methods to improve sports performance [11]. Cold beverages ingested into the stomach readily extract heat from the body. The benefits of ingesting cold beverages are that they may provide cooling, and deliver nutrients (e.g. carbohydrates). It is well established that fluid ingestion plays an important role in supporting exercise performance in the heat. Ingestion of ice, or cold beverages are known to affect skin temperature, skin blood flow and sweat rate [11]. Heat acclimatization is the physiological adaptation that occurs after regular exposure to hot environments. This will result in a number of physiological adaptations that reduce the negative effects of exercise in the heat. The process of acclimatization to exercise in the heat begins within a few days and it might take 7 to 14 day for full adaptation [13]. Brain mechanisms and thermoregulation. Several neurotransmitter systems seem to be involved in thermoregulation, and although the original central fatigue hypothesis emphasizes that an exercise-induced increase in serotonin is responsible for the development of fatigue, this theory seems too basic. Several studies using pharmacological and nutritional interventions, attempted and failed to alter exercise capacity through changes in serotonergic neurotransmission in humans, indicating that the role of serotonin is often overrated [6,7]. Evidence from different studies suggests that it is very unlikely that one neurotransmitter system is responsible for the appearance of central fatigue. The exact mechanism of fatigue is not known, presumably a complex interplay between both peripheral and central factors induces fatigue [6]. Also, the ingestion of Branched Chain 15

16 Amino Acids does not influence exercise and cognitive performance in normothermia or when exercise is performed in the heat [5]. Recent studies, investigating the inhibition of the reuptake of both dopamine and noradrenaline, were capable of detecting changes in performance, specifically when ambient temperature was high [8-10, 12]. Dopamine and noradrenaline are prominent in innervated areas of the hypothalamus, therefore changes in the catecholaminergic concentrations may also be expected to be involved with the regulation of body core temperature during exercise in the heat. The thermoregulatory center of the body is located in the Preoptic Area and the Lateral Hypothalamus. Injection of a neurotoxin in this brain region clearly showed that exercise performance in rats is reduced due to the incapability to activate heat loss mechanisms [2]. When a selective dopamine/noradrenaline reuptake inhibitor was administered to rats running on a treadmill in high ambient temperature, the time to exhaustion increased, while core and brain temperature increased. Tail temperature, an indication of heat loss mechanism, however decreased indication that the dopaminergic drive (stimulation other brain areas) positively influenced performance, but created hyperthermia [3]. This phenomenon was also observed in our studies where we manipulated neurotransmission of athletes performing in the heat [7-10, 12 for review see 6]. There has been some interest in using neurotransmitter precursors to influence performance in the heat. Tyrosine protects against the adverse effects of heat, suggesting these effects result from increased central release of noradrenaline. There are indications that the effects of tyrosine generalize across dissimilar stressors, and that tyrosine administration may mitigate the adverse behavioral effects of heat and other stressors on humans. Conclusions Exercise in the heat can negatively affect performance. Several methods such as keeping euhydrated, pre-cooling, nutritional interventions such as optimizing carbohydrate levels are used by athletes. The central nervous system plays a crucial role in thermoregulatory mechanisms, and neurotransmitter systems such as the noradrenergic and dopaminergic system are influencing thermoregulation. References 1. Gonzalez-Alonso J, Teller C, Andersen SL, Jensen FB, Hyldig T, Nielsen B. Influence of body temperature on the development of fatigue during prolonged exercise in theheat. J Appl Physiol; 86(3): , Hasegawa H, Ishiwata T, Saito T, et al. Inhibition of the preoptic area and anterior hypothalamus by tetrodotoxin alters thermoregulatory functions in exercising rats. J Appl Physiol; 98 (4): , Hasegawa H, Piacentini MF, Sarre S, et al. Influence of brain catecholamines on the development of fatigue in exercising rats in the heat. J Physiol; 586 (1): , Kenefic R & Cheuvront S. Hydration for recreational sport and physical activity. Nutrition Reviews Vol. 70 (Suppl. 2): S137 S142, Lieberman H. Methods for assessing the effects of dehydration on cognitive function. Nutrition Reviews. Vol. 70 (Suppl. 2): S143 S146, Meeusen R, Roelands B. Central fatigue and neurotransmitters, can thermoregulation be manipulated? Scand J Med Sci Sports, 20 (Suppl 3):19 28, Roelands B, Goekint M, Buyse L, Pauwels F, De Schutter G, Piacentini F, et al. Time trial performance in normal and high ambient temperature: is there a role for 5-HT? Eur J Appl Physiol;107 (1): , Roelands B, Goekint M, Heyman E, Piacentini MF, Watson P, Hasegawa H, et al. Acute norepinephrine reuptake inhibition decreases performance in normal and high ambient temperature. J Appl Physiol, 105 (1): , Roelands B, Hasegawa H, Watson P, Piacentini MF, Buyse L, De Schutter G, et al. The effects of acute dopamine reuptake inhibition on performance. Med Sci Sports Exerc,40(5): , Roelands B, Watson P, Cordery P, Decoster S, Debaste E, Maughan R, et al. A dopamine/noradrenaline reuptake inhibitor improves performance in the heat, but only at the maximum therapeutic dose. Scand J Med Sci Sports; 22(5) : 93 98, Ross M, Abbiss C, Laursen P, Martin D, Burke L. Precooling Methods and Their Effects on Athletic Performance. A Systematic Review and Practical Applications. Sports Med, 43: , Watson P, Hasegawa H, Roelands B, Piacentini MF, Looverie R, Meeusen R. Acute dopamine/noradrenaline reuptake inhibition enhances human exercise performance in warm, but not temperate conditions. J Physiol, 565 (Pt 3): , Wendt D, van Loon L, van Marken Lichtenbelt W. Thermoregulation during Exercise in the Heat Strategies for Maintaining Health and Performance. Sports Med; 37 (8): ,

17 6 Dietary protein and short-term muscle disuse Luc J.C. van Loon Maastricht University, Maastricht Introduction Recovery from injury and illness generally necessitates prolonged periods of muscle disuse or unloading in otherwise healthy athletes. Under such conditions, there is a progressive loss of skeletal muscle mass that results in impaired functional strength, reduced insulin sensitivity, a decline in basal metabolic rate, and a concomitant increase in body fat mass (19). For these reasons, prolonged muscle disuse forms a significant concern in several populations, ranging from the competitive athlete to the patient. Though it has been well established that nutrition represents an important factor regulating the maintenance of muscle mass, less consideration has been directed at developing effective nutritional strategies to attenuate or even prevent muscle loss during short or more prolonged periods of muscle disuse due to illness or injury. Disuse and the loss of skeletal muscle mass and strength Since the inception of bed rest and limb immobilization as models to study skeletal muscle disuse in human volunteers, there have been numerous studies addressing the impact of a decline in physical activity status on skeletal muscle mass and strength (see Table 1). During disuse, skeletal muscle loss occurs at a rate of approximately 0.5% of total muscle mass per day (Figure 1). This translates into approximately 150 g of muscle tissue lost per day in a healthy adult, resulting in more than 1 kg of muscle mass lost after a single week. Though earlier studies suggest that this is largely attributable to specific type I muscle fiber atrophy, others report type I and type II muscle fiber atrophy following more prolonged periods of muscle disuse. Interestingly, recent evidence indicates that type II muscle fibers are more susceptible to disuse atrophy. The substantial loss of skeletal muscle mass during disuse is accompanied by a decline in strength that ranges between 0.3% and 4.2% per day (9, 11, 14). When put into perspective, a person who is normally capable of lifting 100 kg with a single leg extension would hardly be able to lift 80 kg after only 2 weeks of limb immobilization or bed rest. It is apparent that the onset of muscle disuse results in a remarkably greater relative loss of muscle strength when compared with the actual loss of muscle mass. This is generally attributed to changes in motor unit recruitment that likely occur prior to muscle tissue atrophy due to deconditioning. Disuse and skeletal muscle protein synthesis and breakdown Skeletal muscle protein turns over at a rate of ~1 2% per day. In a healthy, weight-stable young athlete, this equates to g of muscle protein that is broken down and resynthesized over 24 h. This process is regulated via the dynamic balance between muscle protein synthesis and breakdown. For a substantial change in skeletal muscle mass to occur, a chronic imbalance between muscle protein synthesis and breakdown must exist. In case of muscle disuse atrophy, this can occur via a sustained increase in muscle protein breakdown, a prolonged decrease in muscle protein synthesis, or a combination of both. In general, previous work indicates that muscle protein breakdown rates do not change significantly during 2 3 weeks of bed rest. As such, it is generally believed that muscle atrophy during a prolonged period of disuse is mainly attributable to a reduction in the rate of muscle protein synthesis. Much of the decline in muscle mass during disuse atrophy seems to occur during the early stages of immobilization (Figure 2). This rapid loss of muscle tissue during first few days of bed rest (8) or limb immobilization (10) is unlikely to be exclusively due to a reduction in the basal muscle protein synthesis rate. Therefore, it should be noted that increased levels of muscle protein breakdown may also contribute substantially during the first few days of muscle disuse. Protein and/or amino acid ingestion stimulates muscle protein synthesis and inhibits muscle protein breakdown, resulting in a positive net protein balance. This postprandial stimulation of muscle protein synthesis is driven mainly by the subsequent increase in plasma essential amino acid availability. As such, food intake stimulates postprandial muscle protein accretion, thereby offsetting the negative protein balance in the overnight fasted state. As a consequence, postprandial stimulation of muscle protein synthesis is another important factor in regulating muscle mass maintenance. Recent studies suggest that impairments in postprandial stimulation of muscle protein synthesis, coined anabolic resistance, also contribute to the loss of muscle mass with aging. It is suggested that muscle disuse desensitizes skeletal muscle tissue to respond to anabolic stimuli (3). This opens up the possibility that nutritional strategies that compensate for the greater anabolic resistance may also be applied effectively to attenuate muscle disuse atrophy. 17

18 Nutritional strategies to attenuate muscle loss during disuse A period of bed rest or limb immobilization inevitably leads to a reduction in physical activity and, therefore, a concomitant decline in energy requirements. A period of muscle disuse enforced by illness or injury, however, also greatly reduces appetite such that individuals generally consume insufficient food to maintain energy balance. This will result in losing even more muscle tissue during a period of bed rest when compared with volunteers who are able to maintain energy balance (1). In agreement, a diet that does not maintain energy balance has been shown to lower basal muscle protein synthesis rates by ~20% (12). Therefore, avoiding under-nutrition is a requirement to prevent accelerated muscle loss during a period of hospitalization and/or bed rest. The key factor responsible for accelerated loss of skeletal muscle tissue during a period of reduced food intake and muscle disuse may not be the lower energy intake per se, but rather a reduced protein intake. Habitual protein intake in a healthy individual usually constitutes ~10 15% of total energy intake. For a healthy 75 kg male consuming 10 MJ per day, this would equate to ~60 90 g protein daily ( g protein per kg body mass). When daily protein intake falls well below 0.8 g per kg body weight per day, it becomes difficult to maintain muscle mass. Therefore, to allow proper dietary protein intake under conditions of reduced energy intake, the macronutrient composition of the diet should be modulated. In keeping with this, it has been reported that increasing dietary protein intake (while maintaining total energy intake) improves wholebody nitrogen balance during a 7-day period of bed rest. Nevertheless, even when daily protein intake is maintained at a relative high level ( per kg body weight), substantial loss of muscle tissue still occurs (15, 16). The loss may be even greater in athletes who habitually consume large amounts of dietary protein in their diet. Adequate postprandial stimulation of muscle protein synthesis is a key factor in maintaining muscle mass on a daily basis. Therefore, dietary strategies that can compensate for anabolic resistance by increasing the muscle protein synthetic response to food intake should be able to attenuate muscle mass loss during muscle disuse. Previous work has shown that the postprandial muscle protein synthetic response to food intake can be modulated by changing the amount and type of dietary protein ingested and the timing of the meals provided throughout the day. Protein or essential amino acid ingestion stimulates muscle protein synthesis rates in a dose-dependent manner (2). It has been suggested that an ingested dose of ~20-25 g protein (or g crystalline essential amino acids) is sufficient to maximally stimulate postprandial muscle protein synthesis rates in healthy young individuals. Furthermore, to maximize the muscle protein synthetic response to protein ingestion a high quality protein should be selected, characterized by rapid digestion and absorption kinetics and a relative high essential amino acid content (and a high leucine content in particular (17)). As muscle protein synthesis rates are elevated for 2-4 hours into the postprandial period, athletes are often advised to consume 5-6 meals per day. The same logic may also apply to situations of muscle disuse. A well-planned schedule of more than 3 meals per day, each containing sufficient protein to allow a maximal postprandial anabolic response may represent a more effective means to attenuate muscle loss during disuse. This includes the proposed ingestion of a single bolus of dietary protein prior to sleep (4). Besides dietary protein, various specific nutritional compounds have been suggested to further stimulate muscle protein accretion and/or attenuate muscle loss. Oral creatine supplementation (20 g per day) has been reported to attenuate the loss of muscle mass and strength during 7 days of unilateral upper arm immobilization (7). In addition, creatine supplementation may also be of benefit during rehabilitation following a period of disuse. It has been demonstrated that oral creatine supplementation (20 g down to 5 g daily) during lower limb immobilization and subsequent rehabilitation improves muscle mass regeneration (5, 6). Recently, some interesting work suggested that prolonged supplementation with fish-oil- derived omega-3 fatty acids (4 g per day for 8 weeks) can augment the muscle protein synthetic response to amino acid administration (13). This may provide an effective strategy to alleviate the muscle mass loss during a short period of disuse. Other nutritional strategies are currently being developed. Besides nutritional interventions, surrogate ways of stimulating physical activity or muscle contraction are being evaluated. Recently, we showed that neuromuscular electrical stimulation represents an effective means to stimulate in vivo muscle protein synthesis (18). More recent work from our lab shows that daily sessions of electrical stimulation can prevent the loss of muscle during limb immobilization. The latter provides an exciting new approach that could proof to be of substantial relevance to prevent the loss of muscle mass and strength, and combinations with proper nutritional co-interventions are being developed. Conclusions Periods of muscle disuse occur regularly in otherwise healthy humans for several reasons, such as the recovery from serious injury or illness. The loss of skeletal muscle mass and strength that occurs during such short periods of muscle disuse has substantial impact on athletic performance capacity. Mechanistically, muscle atrophy during prolonged muscle disuse (>10 days) has been attributed to a decline in both basal and postprandial muscle protein synthesis rates, with little changes in muscle protein breakdown. Indirect evidence, however, suggests that rapid muscle loss during the first few days of immobilization is facilitated by an early and transient (1 5 days) increase in muscle protein breakdown. A period of muscle disuse reduces energy requirements and appetite. Consequently, food intake generally declines, resul- 18

19 ting in inadequate dietary protein consumption to allow proper muscle mass maintenance. Maintaining dietary protein intake is required to attenuate muscle loss during a period of disuse. Specific supplementation with food sources high in protein and/or the use of essential amino acid/protein supplements can be applied to compensate for anabolic resistance due to disuse and, as such, to augment postprandial muscle protein synthesis rates. Other nutritional compounds, such as creatine or omega-3 fish oils, may be of additional interest to attenuate the loss of muscle mass and strength during short periods of muscle disuse. Neuromuscular electrostimulation can be applied as a surrogate for physical activity and/or exercise when one or more limbs are temporarily immobilized. Table 1. Leg immobilization and its impact on muscle mass and strength Reference Duration (days) Loss of muscle mass Loss of strength Schoneyder et al Ingemann-Hansen 35 26% in quadriceps CSA - et al. Häggmark et al. 35 type I fibers, no change in type II fibers - White et al. 7 & 14 5% (7 d) and 8% (14 d) quadriceps CSA 11% (7 d); 24% (14 d) Lindboe et al. 3 14% type I fiber CSA, no change type - II fiber CSA Gibson et al. 37 8% thigh volume, 14% type I fiber - CSA, no change type II fiber CSA Davies et al % in quadriceps CSA Wigerstad-Lossing 21 et al. Gibson et al % in quadriceps CSA - Virtanen et al % in quadriceps CSA - Berg et al. 28 7% in quadriceps CSA 20% Dudley et al % in quadriceps CSA 20% Berg et al % Veldhuizen et al % quadriceps CSA, 16% mixed 25-50% fiber CSA Blakemore et al. 7 & 42 8% type I fiber CSA (7 d); 29% in - type I fiber CSA and 36% in type II fiber CSA (42 d) Berg et al % Gamrin et al % Hortobágyi et al and 10% type I and II fiber CSA 47% Thom et al % quadriceps CSA 42% Hespel et al % quadriceps CSA - Labarque et al % Schulze et al. 21 7% in quadriceps CSA 17% Carrithers et al % quadriceps mass - Jones et al. 14 5% quadriceps mass 27% Yasuda et al. 14 6% quadriceps CSA, 4% quadriceps 10% lean mass, 5, 8 and 11% type I, II and IIx fiber CSA, respectively Urso et al. 2 de Boer et al. 14 & 23 5% (14 d) and 10% (23 d) quadriceps CSA 15% (14 d); 21% (23 d) Chen et al Tesch et al Glover et al. 14 5% quadriceps CSA, 5% quadriceps 25% mass Christensen et al. 14 6% triceps surae CSA 9% Christensen et al % triceps surae CSA 54% Seynnes et al. 14 & 23 5% (14 d) and 8% (23 d) muscle 10% (14&23 d) volume Deschenes et al Abadi et al. 2 & Gustafsson et al Glover et al. 2 & 14 6% quadriceps CSA (14 d) - Sato et al. 20 6% leg volume - Hvid et al % in all muscle fiber type CSA 25% For the purposes of comparison: all types of isometric, concentric, or eccentric strength tests have been termed strength; where no direct measures are reported for muscle atrophy or protein turnover, any relevant surrogate markers are reported when available; MPS values are reported as fractional synthetic rate (FSR) wherever possible and whole body measures are referred to as protein synthesis; loss of muscle mass and strength have been converted to % changes. Abbreviations BCAA, branch chain amino acids; CSA, cross sectional area; MPS, muscle protein synthesis; MPB, muscle protein breakdown; UPS, ubiquitin proteasome system. Table 1 Lower limb immobilization and its impact on muscle mass and strength. Table derived from Wall and van Loon, Nutr Rev,

20 Figure 1 Relationship between the duration of muscle disuse and the subsequent rate of muscle loss expressed in percentage of muscle lost per day. Graph is collated using data from the studies presented in Wall and van Loon (Nutr Rev, 2012), which used either a bed rest, a lower limb immobilization or an upper limb immobilization model of muscle disuse in human volunteers and concurrently measured muscle atrophy on the whole muscle level. References 1. Biolo G, Ciocchi B, Stulle M et al. (2007) Calorie restriction accelerates the catabolism of lean body mass during 2 wk of bed rest. Am J Clin Nutr. 86, Bohé J, Low A, Wolfe R et al. (2003) Human muscle protein synthesis is modulated by extracellular, not intramuscular amino acid availability: a doseresponse study. J Physiol Glover E, Phillips S, Oates B et al. (2008) Immobilization induces anabolic resistance in human myofibrillar protein synthesis with low and high dose amino acid infusion. J Physiol 586, Groen B, Res P, Pennings B et al. (2012) Intragastric protein administration stimulates overnight muscle protein synthesis in elderly men. Am J Physiol Endocrinol Metab 302, Hespel P, Op t Eijnde B, Van Leemputte M et al. (2001) Oral creatine supplementation facilitates the rehabilitation of disuse atrophy and alters the expression of muscle myogenic factors in humans. J Physiol 536, Hespel P, Op t Eijnde B, Van Leemputte M et al. (2001) Oral creatine supplementation facilitates the rehabilitation of disuse atrophy and alters the expression of muscle myogenic factors in humans. J Physiol 536, Johnston A, Burke D, MacNeil L et al. (2009) Effect of creatine supplementation during cast-induced immobilization on the preservation of muscle mass, strength, and endurance. J Strength Cond Res 23, Kortebein P, Ferrando A, Lombeida J et al. (2007) Effect of 10 days of bed rest on skeletal muscle in healthy older adults. JAMA 297, LeBlanc A, Schneider V, Evans H et al. (1992) Regional changes in muscle mass following 17 weeks of bed rest. J Appl Physiol 73, Lindboe C & Platou C (1984) Effect of immobilization of short duration on the muscle fibre size. Clin Physiol 4, Paddon-Jones D, Sheffield-Moore M, Urban R et al. (2004) Essential amino acid and carbohydrate supplementation ameliorates muscle protein loss in humans during 28 days bedrest. J Clin Endocrinol Metab. 89, Pasiakos S, Vislocky L, Carbone J et al. (2010) Acute energy deprivation affects skeletal muscle protein synthesis and associated intracellular signaling proteins in physically active adults. J Nutr. 140, Smith G, Atherton P, Reeds D et al. (2011) Omega-3 polyunsaturated fatty acids augment the muscle protein anabolic response to hyperinsulinaemia-hyperaminoacidaemia in healthy young and middle-aged men and women. Clin Sci (Lond) 121, Thom J, Thompson M, Ruell P et al. (2001) Effect of 10-day cast immobilization on sarcoplasmic reticulum calcium regulation in humans. Acta Physiol Scand 172, Trappe S, Creer A, Slivka D et al. (2007) Single muscle fiber function with concurrent exercise or nutrition countermeasures during 60 days of bed rest in women. J Appl Physiol 103, Trappe T, Burd N, Louis E et al. (2007) Influence of concurrent exercise or nutrition countermeasures on thigh and calf muscle size and function during 60 days of bed rest in women. Acta Physiol (Oxf) 191, van Loon L (2011) Leucine as a pharmaconutrient in health and disease. Curr Opin Clin Nutr Metab Care 15, Wall BT, Dirks ML, Verdijk LB et al. (2012) Neuromuscular electrical stimulation increases muscle protein synthesis in elderly, type 2 diabetic men. Am J Physiol Endocrinol Metab 303: E614 E Wall BT and van Loon L.J.C (2013) Nutritional strategies to attenuate muscle disuse atrophy. Nutr Rev 71(4):

21 7 Nutrition for post-exercise recovery a review of current opinion Louise M Burke Australian Institute of Sport Recovery has become an industry with athletes now having access to Recovery Centres, Recovery Experts, Recovery drinks and Recovery Bars. The spotlight on sports nutrition is a beneficial outcome of this interest. Nevertheless there is a downside in that many athletes have come to consider recovery eating as a One-Size- Fits-All, Must-Do-at-Every- Opportunity activity. In fact, post-exercise recovery requires a situation-specific solution for each session. Misguided recovery eating can cause a drain on the wallet. More importantly, it can cause nutrition problems such as weight gain due to unnecessary or excessive intake of kilojoules or even a failure to promote optimal recovery and adaptation to a training program. Understanding the issues and goals for post-exercise Recovery between exercise sessions may have two separate goals: Restoration of body losses/changes caused by the first session to restore performance levels for the next Adaptive responses to the stress/stimulus provided by the session to gradually make the body become better at the features of exercise that are important for performance Obviously, the chief focus between races in a competition schedule is to restore homeostasis or depleted nutrients as quickly as possible to optimal performance levels - or at least a performance level that is better than that of your opponent or fellow competitors. Of course, some light workouts or easy competition scenarios may not create any major demands at all. In the case of key training sessions, the focus of recovery eating may shift more to the second goal of adaptation. In this regard, there is a new hypothesis that exercising within an environment of low nutritional support might stimulate greater adaptation to the same training stimulus (a training smarter rather than training harder approach). This has recently been explored in relation to carbohydrate intake based on observations from cellular observations that when exercise is undertaken with low muscle glycogen content, the transcription of a number of genes involved in training adaptations is enhanced (for review, see Philps et al 2012). There are a number of potential ways to reduce carbohydrate availability in training or recovery environments, including doing two training sessions in close succession without opportunity for refuelling, training in a fasted state with only water intake, and withholding carbohydrate during the early recovery period (Burke 2011). The concept of including some sessions of this type ( train low ) within the periodised training calendar is a topic of great interest that requires further research and experimentation. A further differentiation in recovery eating arises from the variation in physiological stresses encountered in each workout or event. Each session differs in how much you sweat, deplete muscle fuel stores, stimulate protein synthesis, or cause damage and disruption to the body. Therefore, different types and amounts of nutrients will be needed to restore normal status. How important it is to deliver those nutrients to the body as soon as possible will depend on whether these nutrients are handled differently in the post-exercise phase and how long it will take to achieve restoration (Burke and Jeacocke 2011). The bottom line is that each session deserves its own recovery eating plan, and this may differ from athlete to athlete. Nutritional strategies to promote post-exercise recovery Recovery after exercise involves a complex array of processes that help to restore homeostasis or allow the body to adapt to physiological stress. The better understood processes include restoration of muscle and liver glycogen stores, replacement of fluid and electrolytes lost in sweat, protein synthesis for repair and adaptation, and responses of the immune and anti-oxidant systems to help the athlete stay healthy. When these processes are desired, provision of nutrients in the hours after the session will help to optimise the recovery outcome. When refuelling is a priority, athletes are advised to consume carbohydrate as soon as possible after the completion of a workout or event. This is partly because of observations that glycogen synthesis rates are highest when carbohydrate is consumed in the first 2-4 hours after exercise (Ivy et al.1988). Although this observation has created the idea of a window of opportunity for post-exercise glycogen storage, the true value of carbohydrate intake after exercise is that, at any timepoint, there will be low rates of glycogen restoration without provision of a substrate. Any delay is important when there is only 4 to 8 hr between exercise sessions, but it may have less impact over a longer recovery period, as long as sufficient carbohydrate is consumed (for review, see Burke et al. 2004). Rehydration can only commence with the intake 21

22 of fluids, however, the simultaneous replacement of electrolytes via the intake of sodium-containing drinks or the co-ingestion of foods with salt-containing foods or meals is required to promote effective restoration of body fluid status. A summary of post-exercise fluid need is provided by Shirreffs and colleagues (2004). In the period immediately after exercise, there is a substantial increase in rates of muscle protein synthesis, especially in trained individuals (Tang et al. 2008). This is most evident in the hours immediately after the exercise bout, and in trained subjects, it may not return to basal levels until at least 24 hr of recovery (Tang et al. 2008). However, while exercise reduces the degree of negative protein balance that occurs between meals, the response remains negative (i.e. breakdown > synthesis) unless the athlete consumes a source of protein (Biolo et al 1997), or more specifically, essential amino acids. The maximal protein synthetic response to a resistance exercise bout is achieved with the intake of ~ g of high quality protein, and protein consumed in excess of this stimulates increased rates of irreversible oxidation (Moore et al. 2009). Continuing such a pattern of intake of high quality protein over the day (Areta et al. 2013) and before bed (Res et al ) will help to promote optimal protein synthesis over the day. Finally, the recovery period will involve some adaptation to the exercise-induced stress to the body s immune and antioxidant status, but specific nutritional strategies to promote or preserve optimal anti-oxidant and immune function in athletes are not well described. Reduced carbohydrate availability during exercise induces larger increases in stress hormones and greater perturbation of immune function parameters in the window of immunosuppression after the exercise bout (Gleeson 2007). Low energy availability is also known to disturb immune healthy. The body s anti-oxidant system is a similarly complicated arrangement, and further work is required to determine whether supplementation with special nutrients in foods such as anti-oxidants and plant phytochemicals can promote anti-oxidant status, reduce muscle damage, promote mitochondrial biogenesis and enhance sports performance (Reid 2008). Further research is required. Of course, even when goals for an optimal nutrient intake immediately after exercise can be clearly specified, there may be practical issues that delay or reduce the athlete s capacity to consume appropriate amounts or types of foods and fluids to achieve such guidelines. Eating and drinking during the recovery period may be interrupted by the scheduling of other events (e.g. media obligations, drug testing, post-event debriefing) or by a loss of appetite. Access to suitable foods and drinks may be limited in some exercise environments, and the culture of some sports may promote detrimental eating practices such as excessive intake of alcohol. In some cases, such practical issues may be more challenging to optimal nutrient timing than the lack of clear guidelines. Table 1 provides an overview of nutritional strategies that promote recovery after exercise, and the times in which they may be useful or expendable Nutritional considerations for promoting optimal sleep Sleep plays a key role in recovery after exercise and in the support for optimal health and performance. Strategies to promote ideal sleep patterns, focussing on sleep onset and the quality and duration of sleep now form a large interest in Recovery Science. Indeed, there are now experts on Sleep Hygiene as well as specialised products such as relaxation drinks (which might be seen as the opposite of energy drinks ). Common ingredients in these drinks include tryptophan, valerian, melatonin, kava, L-theanine and magnesium, all with various degrees of evidence to support their ability to promote or enhance sleep and relaxation (Stacy 2011). Other nutritional strategies under investigation for the potential to assist with sleep goals include the intake of a solid carbohydrate-rich meal or snack late in the day or prior to sleep, and the intake of foods rich in tryptophan, which appear to be as effective as the intake of isolated tryptophan (Hudson et al. 2007). Some nutritional practices, including strategies which may be implemented to assist with other goals of sports nutrition, can interfere with sleep. These include the intake of caffeine in large amounts or late in the day (which can increase sleep latency and reduce the quality and duration of sleep), the intake of large amounts of food (which can cause gut discomfort), and the intake of large amounts of fluid (which can interfere with sleep due to the need to urinate overnight). Such practices need to be balanced against overall goals of recovery. 22

23 References 1. Areta, J.L., L.M. Burke,M.L. Ross. D.M. Camera, D.W. West, E.M. Broad, N.A. Jeacocke, D.M. Moore, T. Stellingwerff, S.M. Phillips, J.A. Hawley, and V.G. Coffey Timing and distribution of protein ingestion during prolonged recovery from resistance exercise alters myofibrillar protein synthesis. Journal of Physiology 1;591(Pt 9): Burke, L.M. and N.A. Jeacocke In: Kerksick, C. M (ed). The basis of nutrient timing and its role in sport and metabolic regulation. In: Kerksick CM. (ed) Nutrient Timing: Metabolic Optimisation for Health, Performance and Recovery, pp Boca Raton FL, CRC Press. 3. Burke, L. M., B. Kiens, and J. L. Ivy Carbohydrates and fat for training and recovery. Journal of Sports Sciences. 22: Burke, L.M Fuelling strategies to optimise performance training high or training low? Scandinavian Journal of Medicine and Science in Sports Oct;20 Suppl 2: Gleeson, M Immune function in sport and exercise. Journal of Applied Physiology. 103: Hudson, C., S. Hudson and J. MacKenzie Protein-source tryptophan as an efficacious treatment for social anxiety disorder: a pilot study. Canadian Journal of Physiology and Pharmacology. 85: Ivy, J. L., A. L. Katz, C. L. Cutler, W. M. Sherman, and E. F. Coyle Muscle glycogen synthesis after exercise: effect of time of carbohydrate ingestion..journal of Applied Physiology. 64 (4): Moore, D. R., M. J. Robinson, J. L. Fry, J. E. Tang, E. I. Glover, S. B. Wilkinson, T. Prior, M. A. Tarnopolsky, and S. M. Phillips Ingested protein dose response of muscle and albumin protein synthesis after resistance exercise in young men. The American Journal of Clinical Nutrition. 89: Philp, A., L.M. Burke, and K. Baar K Altering endogenous carbohydrate availability to support training adaptations. Nestle Nutrition Institute Workshop Series,69: Reid, M. B Free radicals and muscle fatigue: Of ROS, canaries, and the IOC. Free Radicals in Biology and Medicine. 44: Res, P.T., B. Groen, B. Pennings, M. Beelen, G.A.Wallis. A.P. Gijsen, J.M. Senden, and L.J van Loon Protein ingestion before sleep improves postexercise overnight recovery. Medicine and Science in Sports and Exercise, 44: Shirreffs, S. M., L. E. Armstrong, and S. N. Cheuvront Fluid and electrolyte needs for preparation and recovery from training and competition. Journal of Sports Sciences. 22: Stacy, S Relaxation drinks and their use in adolescents. Journal of Child and Adolescent Psychopharmacology, 21: Tang, J. E., J. G. Perco, D. R. Moore, S. B. Wilkinson, and S. M. Phillips Resistance training alters the response of fed state mixed muscle protein synthesis in young men. American Journal of Physiology - Regulatory, Integrative and Comparative Physiology. 294: R

24 P A R I S for more information: