The Role of Milk in a Dietary Strategy to Increase Muscle Mass and Improve Recovery: Case Study of an Elite Sprint Kayaker Dr Karen Reid, Ph.D, Registered Dietitian Member of the UK Sport and Exercise Nutrition Register (SENr) Director Performance Food Ltd. PO Box 58, Swansea SA3 4WX, UK. E-mail: karen@performancefood.co.uk Website: www.performancefood.co.uk The author is the Director of Performance Food Ltd and undertook the work described in this case study as part of her consultancy work with Performance Food Ltd. The athlete has read, approved, and provided written permission for this case study to be submitted for the Dairy Council Awards. KEY WORDS Sports nutrition, kayaking, recovery, milk, protein, muscle mass ABSTRACT Flatwater kayaking requires upper-body muscle strength and a lean body composition. This case study describes a nutrition intervention with a 19 year-old male elite Sprint Kayaker to increase muscle mass. Prior to the intervention daily energy intake was 3247 kcal (protein 1.8 g/kg, carbohydrate 3.6 g/kg) and the athlete was unable to eat sufficient food to meet the energy demands of training. During the intervention the athlete s daily energy intake increased to 5279 kcal (protein 3.2 g/kg, carbohydrate 7.7 g/kg) by including milk based drinks pre and posttraining and before bed. This simple dietary intervention, along with a structured strength and conditioning programme, resulted in an increase of 10 kg body mass without any significant change in body fat. In addition the athlete reported the milk based drinks were easy to consume, and for the first time, was able to maintain weight during intensive phases of the training cycle. INTRODUCTION The case study is a 19 year-old male Sprint Kayaker racing over K200, K500 and K1000 distances and member of the British Canoe Union (BCU) Olympic Development Programme (ODP) and National under 23 training squad based at Teddington. As Kayaking is a sport which requires upper-body muscle strength and a lean body composition (Michael et al. 2008) the athlete s aim was to focus on his physical development and increase muscle mass and strength. He was set a target by his Great Britain (GB) sprint coach to increase body mass to 85 kg by January 2014 and 90 kg by January 2015. DESCRIPTION AND RATIONALE The athlete was referred for nutrition support in January 2013 by his strength and conditioning coach who was concerned that he was fatigued and not recovering well between training sessions. At that time he was a member of the GB Junior Development squad, ranked 5th in the UK in his age group and weighed 78 kg. A further consideration was the athlete required surgery on his wrist during September 2013 and underwent a 6 week rehabilitation period before resuming his weight training in November 2013.
An initial assessment of nutritional intake and energy requirements was performed along with body composition analysis and a blood test to measure Vitamin D status. A nutrition intervention was developed to support the athlete s training goals. An important focus was to ensure day-to-day energy needs were being met and a positive energy balance for growth and development of muscle mass. A further goal for the athlete was to maintain weight during intensive training phases such as overseas training camps and during racing regattas as he had previously lost the muscle mass gained from winter weight training. Post-exercise nutrition was considered a priority for the athlete to improve recovery and optimise muscle protein synthesis. Studies have demonstrated that protein ingestion postexercise increases the rate of muscle protein synthesis and suppresses muscle protein breakdown (Phillips et al. 2005). Moore et al. (2009) concluded the optimum protein intake for promoting net muscle protein gain was 20 g; therefore 20-25 g protein with carbohydrate was advised post-exercise. Whole milk ingestion post-exercise has been shown to enhance muscle protein synthesis and gains in fat free mass. Evidence suggests that dairy proteins (casein, whey) are most effective in stimulating muscle protein synthesis (Tipton et al. 2004). Whey protein has also been found to enhance muscle protein synthesis rates over casein due to differences in digestion and absorption kinetics affecting the uptake of amino acids into muscle (Wilkinson et al. 2007). A further study (Cockburn et al. 2008) compared semi-skimmed milk and a flavoured milk drink with a sports drink or water after eccentric exercise. Results showed improved recovery from the muscle damaging exercise in those who consumed both the milk and flavoured milk drink but not for those who consumed the sports drink or water. Notably, milk has a naturally high electrolyte content which has been shown to aid fluid retention and have added benefits postexercise as a rehydration drink. Other studies have also suggested that consumption of low fat milk post-exercise was more effective than water or a 6% carbohydrate electrolyte drink at restoring and maintaining hydration (Shirreffs et al. 2007; Watson et al. 2008). CASE PRESENTATION The athlete lives with his parents in Maidstone (Kent) and studying for A Levels. He trains twice each day with one rest day (Sunday) and also attends GB under 23 training sessions at Dornay, Teddington and Bisham which involves staying in a shared house with the London based Kayakers and preparing his own food. Table 1 describes a typical training and school day routine.
Table 1 Typical Daily Food Intake and Training Activity Pre-intervention Activity Food or Drink 5:30 am: 1 st Breakfast 80g Porridge oats, half pint milk, 200 ml orange juice, water 6.00-7.00 am: Paddle Maximum pace, 30 stroke every 2x10x2 7.30 am: 2 nd Breakfast 2 scrambled eggs, 2 slices toast, cream cheese, 200 ml orange juice 8.30 am: School 1.00 pm: Lunchbox at school Pasta salad, ham, mascarpone, peppers, basil, tomato, olive oil 3.50pm: Pre-training snack Ready-made quiche (200 g) 6.00-7.00 pm: Strength training 8.00 pm: Dinner Chicken portion, apricot and coriander cous cous 10.00 pm: Bed Dietary Assessment In order to assess energy and nutrient intake the athlete was asked to complete a food and fluid diary over a 7-day period and instructed to estimate portion sizes using standard household measures, and where possible, information on food labels to record amounts consumed. The athlete also recorded training sessions undertaken over the same 7 day period. On completion of the diary the athlete was contacted by telephone to ask about any foods such as snacks and drinks which may have been forgotten and to clarify preparation methods. The food records were then analysed using dietary-analysis software (Compeat Pro, Nutrition Systems, UK). The athlete s average daily energy intake pre-intervention was 3247 kcal (Table 2) and when compared with the Reference Nutrient Intake (RNI) for his age and activity level an energy deficit of approximately 300 kcal per day was noted. Furthermore his average carbohydrate intake was just 3.6 g/kg and below recommended levels of 5-7 g/kg (IOC, 2010). Baseline assessments are shown in Table 2. Anthropometry The athlete attended the High Performance Sports clinic at University of Kent for physiological and anthropometrical testing. Body composition was assessed using skinfold calipers (Harpenden, UK) at 7 sites by the same operator, a qualified sport and exercise scientist. Results are shown in Tables 2 and 5.
Table 2 Baseline Anthropometric and Nutritional Assessment of the Athlete Athlete characteristic Value Age (years) 18 Height (m) 1.93 Body mass (kg) 78.0 Body mass index (kg/m2) 20.9 Body fat (%) 5.8 Energy intake (kcal) Reference Nutrient Intake (RNI) 3247 3540 Serum vitamin D (nmol/l) 120 (70-200 nmol/l replete) Overview of the Nutritional Intervention A planned approach to recovery within 30 minutes of each training session was developed to ensure replenishment of glycogen stores and a sufficient quantity and quality of protein to stimulate muscle protein synthesis. Flavoured milk was recommended because it provided a source of high-quality dairy proteins (whey and casein) along with carbohydrate, minerals and electrolytes to help replenish muscle glycogen and restore hydration. A bespoke homemade recovery shake was designed consisting of 1 pint of semi-skimmed milk, 50g skimmed milk powder and 50g of a commercial milkshake flavour (Nesquik, Nestle UK) which is fortified with iron, magnesium, calcium, phosphorus, B vitamins and vitamins A, C and D. The milkshake flavour also provided additional carbohydrate to that naturally present in milk. The nutritional composition of the homemade recovery shake is shown in Table 3. The athlete also had access to Maxiraw and Maxifuel nutritional supplements via the GlaxoSmithKline (GSK) partnership with the BCU. In accordance with UK anti-doping guidelines (UKAD, 2013) it was confirmed that these products were batch tested and registered with Informed Sport. Their nutritional composition was evaluated in relation to the athlete s nutritional requirements and compared with the homemade recovery shake (Table 3). Other factors such as cost and the convenience of using a commercial product, for example during overseas training camps and racing regattas were discussed with the athlete. Whilst the Maxiraw whey protein provided 22 g protein per 25 g scoop, there were insufficient calories (92 kcal), carbohydrate (0.5 g) and electrolytes (70 mg sodium) for recovery when used alone with water. However, adding a 25 g scoop to milk or a ready-to-drink flavoured milkshake (Yazoo, Friesland Campina) enhanced the ratio of whey protein to casein and increased calories, carbohydrate, electrolytes and micronutrients as shown in Table 3. An alternative product, Maxifuel RecoverMax offered a better balance of protein and carbohydrate, however nutritional comparisons (shown in Table 3) concluded that 2 servings would be required to achieve the energy, protein and carbohydrate content of the homemade recovery shake.
Table 3 Nutritional Comparison of Commercial Nutritional Supplements (GSK) with a Homemade Recovery Shake using Milk Nutrient Maxiraw whey protein per 25 g scoop in Yazoo flavoured milk (475ml) Maxifuel RecoverMax (400ml) per 75g serving Homemade Recovery shake per pint semi-skimmed milk Energy (kcal) 377 290 637 Protein (g) 36.3 14.5 39 Carbohydrate(g) 46.0 55 103 Fat (g) 6.0 1.2 11.0 Fibre (g) N/A 0.7 0 Sodium (mg) 257 90 537 Potassium (mg) N/A 307 1783 Calcium (mg) 570 125 1346 Magnesium (mg) N/A 152 143 Phosphorus (mg) N/A 27 1061 L-Glutamine (g) N/A 5.0 4.1 * L-Carnitine (mg) N/A 1.0 16.0 Zinc (mg) N/A N/A 5.0 Vitamins N/A N/A A, C, D and B * As Glutamic acid After trialling the options in Table 3 the athlete decided to use the homemade recovery shake on a day-to-day basis after training and continued to use it during a 3 week overseas training camp in Seville (March 2014) and at racing regattas. The 6 am water based training presented a challenge as time was limited for eating a large bowl of porridge which was bulky and difficult to manage before an intensive training session. A trial using a breakfast shake made with 1 pint of full fat milk, 50 g skimmed milk powder, 50 g milkshake flavour, 2 bananas and a 36 g sachet of instant porridge providing 1089 kcal, 48 g protein and 172 g carbohydrate was undertaken. The athlete preferred the convenience of the shake which he was able to consume during his journey to the river and felt more comfortable
during training. A further benefit was the higher energy, protein and carbohydrate content compared to porridge. Table 4 describes the athlete s typical daily food intake during the intervention. Table 4 Typical Daily Food Intake and Training Activity during the Intervention Activity Food or Drink 5:30 am: 1 st Breakfast Breakfast shake, 2 x 65 ml bottles fermented milk (Yakult, UK) 200 ml orange juice, water 6.00-7.00: am Paddle Maximum pace, 30 stroke every 2x10x2 Homemade recovery shake within 30 minutes 7.30 am: 2 nd Breakfast 2 scrambled eggs, 2 slices toast, cream cheese, 200 ml orange juice 8.30 am: School Mid-morning snack Fig roll biscuits or malt loaf, fruit 1.00 pm: Lunchbox at school Pasta salad with Italian tomato sauce chicken, spinach 3.50 pm: Pre-training snack Bowl of cereal, berries, full fat milk 6.00-7.00 pm: Strength training Homemade recovery shake within 30 minutes 8.00 pm: Dinner Baked ham risotto with vegetables. 10.00 pm: Bed Chocolate milkshake Outcome of the Intervention The athlete was reviewed on a regular basis to monitor dietary intake and body mass. Results of the anthropometrical monitoring are shown in Table 5. Contact was maintained during overseas training camps via email and telephone to address any concerns. Body mass increased by 10 kg to 88 kg post-surgery over the intervention period (December 2013 to September 2014) without any significant change in body fat %. Fat mass increased to 8.2% post-surgery and decreased to 6.2% on return to training. During a review on 26 th June 2014 the athlete was advised to increase energy intake further to reflect a higher resting metabolic rate and energy requirements associated with his increased muscle mass. This was achieved by replacing semi-skimmed milk in the homemade shakes with full fat milk. Fat mass remained stable thereafter at approximately 7% indicating energy intake was appropriate.
Table 5 Anthropometric History of the Athlete during the Intervention Period Date of review Body weight (kg) Body fat (%) Training Phase 11/ 012013 78.0 5.8% Baseline assessment 26/11/2013 78.8 8.2% Rehabilitation following wrist surgery 9/12/2013 80.5 6.2% Weight training 27/12/2013 82.5 n/a Weight training 14/01/2014 82.5 n/a Weight training 1/04/2014 84.6 n/a Seville training camp 7/05/2014 85.8 n/a Racing regattas 26/06/2014 84.6 n/a Racing regattas 17/07/2014 86.4 7.6% Racing regattas 26/08/2014 87.8 n/a Racing regattas 29/09/2014 88.0 7.2% Weight training The athlete s average daily energy intake over the intervention increased by 2032 calories to 5279 kcal and average protein and carbohydrate intake to 3.6 and 7.7 g/kg respectively (Table 6). Table 6 Nutritional Intake before and during the Intervention Period Nutrient Pre-Intervention Intervention Energy (kcal) 3247 5279 Protein (g) (g/kg) Carbohydrate (g) g/kg 139 1.8 282 3.6 273 3.2 671 7.7 Fat (g) 181 185 Sodium (mg) 4094 7035 Potassium (mg) 4750 10113 Calcium (mg) 1438 6013 Magnesium (mg) 373 840 The breakfast shake, homemade recovery shakes and chocolate milk before bed supplied 58% of energy intake and 52% and 66% of protein and carbohydrate intake respectively, making a
significant contribution to the athlete s increased nutritional intake. Table 7 presents the nutritional contribution of milk-based drinks. Table 7 Contribution of Milk-based Drinks to the Athlete s total Nutritional Intake Food (per serving) Energy (kcal) Protein (g) Carbohydrate (g) Fat (g) Sodium (mg) Breakfast shake 1089 48.0 172.0 28.5 607 Recovery shake 1 754 38.0 103.0 24.0 537 Recovery shake 2 754 38.0 103.0 24.0 537 Chocolate milk (568 ml) 494 17.5 63.0 21.0 295 Total Total intake (%) 3091 58% 141.5 52% 441 66% 97.5 53% 1976 28% RESULTS AND CONCLUSION The athlete gained a total of 10 kg muscle mass over the dietary intervention without any significant increase in body fat %. His present weight is 88 kg and is now well placed to achieve his target of 90 kg by January 2015. This is the first time that the athlete has been able to maintain weight throughout the years training cycle. Prior to the intervention the athlete was finding it difficult to eat the quantity of food required to meet the high energy demands of his training programme and the initial dietary assessment indicated a chronic shortfall in energy intake. This intervention has demonstrated that milk based shakes and drinks provided a simple, yet effective approach for the athlete to achieve a significant increase in energy and nutritional intake to support gains in muscle mass and recovery after exercise. Furthermore the athlete reported that the milk based shakes and drinks were easy to consume around training and preferred them to the commercial nutritional supplements. Practitioner Reflections Although there are a number of other variables to consider in Sprint Kayaking performance this intervention highlights the importance of maintaining a positive energy balance to support growth and development of muscle mass, especially during intensive training phases. Overall, this case study has shown the significant contribution that milk can make when used in nutrition interventions with athletes and sportspeople to increase and maintain muscle mass.
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