The Science of Marathon Endurance Cardiovascular Factors Cardiac output & blood flow (central factors)

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1 2012 FILEX Fitness Convention Marathon Training 101: Chasing Pheidippides Jason Karp, Ph.D. RunCoachJason.com Founder/Coach, REVO2LT Running Team TM Freelance writer & author 2011 IDEA Personal Trainer of the Year Cardiovascular Factors Cardiac output & blood flow (central factors) Cardiac output dependent on: heart rate (HR) stroke volume (SV) venous return heart contractility amount of pressure in left ventricle (preload) amount of pressure in aorta (afterload) size of left ventricle Cardiovascular Factors Blood flow dependent on: redistribution of blood away from other tissues & to active muscles resistance of blood flow through blood vessels adequate dilation of blood vessels, which depends on interplay between sympathetic & parasympathetic nervous systems & associated hormones O2 transport capacity of blood, which is determined by red blood cell volume & amount of hemoglobin, which transports O2 in blood amount of myoglobin, which transports O2 in muscles density & volume of capillaries that perfuse muscle fibers, which determines time available for diffusion into muscle mitochondria Men have greater cardiovascular endurance than do women because they have greater SV & CO to send more blood & O2 to muscles & more hemoglobin in their blood to transport O2. Muscular Factors Extraction & use of O2 by muscles (peripheral factors) Dependent on mitochondrial & capillary volumes & enzyme activity. Reflected by difference in amount of O2 going to muscles through arterial circulation & amount coming out through venous circulation (a-v O2 difference). a-v O2 difference determined by convection of O2 through muscle capillaries and its diffusion from capillaries to mitochondria. Together, CO & a-v O2 difference determine oxygen consumption (VO2). Fick Equation VO2 = SV x HR x (a-v O2 difference) Central factors VO2 = CO x (a-v O2 difference) Peripheral factors VO2max, the maximum volume of O2 that your muscles can consume per minute, occurs when SV, HR (and therefore cardiac output), & a-v O2 difference are at maximum. Muscular Factors In 1930, David Dill & his colleagues at the Harvard Fatigue Laboratory were among the first physiologists to suggest that there are marked differences in the amount of O2 different people use when running at the same speeds, and that these differences in economy of O2 use is a major factor explaining differences in endurance performance. 1

2 Muscular Factors If two people have same VO2max, but Jack uses 70% & Martin uses % of that VO2max while running at 7:00 pace, the run feels easier for Jack because Jack is more economical. Therefore, Jack can run at faster speed before feeling same amount of fatigue as Martin. Running economy is the oxygen consumption (VO2) used to maintain a specific running speed. biomechanics & motor unit recruitment proportion of slow-twitch muscle fibres capillary & mitochondrial density body weight ability of tendons to store & utilize elastic energy with each step Metabolic Factors Metabolic Factors Lactate Threshold Lactate When pyruvate is converted to lactate, metabolites accumulate & acidosis develops, causing muscles to fatigue & speed to decrease. Slowest speed at which aerobic metabolism (Krebs cycle & electron transport chain) can t keep up with production of pyruvate from glycolysis. Fastest speed above which lactate production begins to exceed its removal, with blood lactate concentration beginning to increase exponentially. Represents transition between running that generates energy almost purely aerobically & running that includes energy from both aerobic & O2-independent (anaerobic) metabolism. LT is an important determinant of marathon performance since it represents the fastest speed that can be sustained aerobically. As speed increases up to LT, contribution from fat decreases & contribution from CHO increases; above LT, only CHO. The 3 Players of Distance Running Running Economy VO2 max Lactate t T hresholdh Metabolic Factors Fuel Use Muscles preferred fuel is CHO. Ability to perform prolonged endurance exercise is strongly influenced by amount of glycogen stored in skeletal muscles, with fatigue coinciding with glycogen depletion. Muscles have enough glycogen to last slightly more than 2 hours of sustained running at moderate intensity. 2

3 Metabolic Factors Fuel Use Glycogen depletion & accompanying low blood sugar (hypoglycemia) coincide with hitting the infamous marathon wall. Marathon requires largest glycogen storage capacity possible, a very efficient capacity to make new glucose (gluconeogenesis), & a very effective use of fat. How do we chase Pheidippides? Mileage Long runs Lactate t (acidosis) i threshold h runs VO2max intervals Taper While women are at a cardiovascular disadvantage to men, they have a greater capacity to metabolize fat & conserve glycogen, which may give them an advantage for very long endurance activities. In 2002 & 2003, Pam Reed beat all the men at the 135-mile Badwater Ultramarathon. Mileage Number of kilometres (or time) run each week is the most important part of marathon training. To run 42.2 km, you need to become as aerobically developed as possible. Improve blood vessels O2-carrying capability by increasing number of red blood cells & hemoglobin Stimulate storage of more fuel (glycogen) in muscles Increase use of intramuscular fat to spare glycogen Create greater capillary network for more rapid diffusion of O2 Increase mitochondrial density & number of aerobic enzymes Improve running economy Long Runs Deplete muscle glycogen to stimulate greater synthesis & storage Stimulate reliance on fat Prepare muscles and connective tissue to handle stress of pounding pavement for 42 km Callous you psychologically for marathon Long Runs Recommendations: Shouldn t comprise more than about 1/3 of weekly mileage. Comfortable pace (about 2 min per mile slower than 5K race pace; ~ 70-75% of max heart rate). Lengthen by 1 mile each week for 3-4 weeks before backing off for recovery week. Keep adding miles until (or about 3-3½ hours, whichever comes first), with final long run 2-3 weeks before marathon. Time spent on feet more important than number of miles. Don t consume carbohydrates during long runs. Since recovery is closely linked to replenishment of carbohydrates, consume carbs immediately afterward grams of simple carbs (e.g., glucose) per kilogram within 30 min & every 2 hrs for 4-6 hrs 3

4 Lactate Threshold Runs Increase speed at which lactate accumulates & acidosis occurs, enabling you to run at higher % VO2max for longer time increasing LT pace allows you to run faster before you fatigue because it allows you to run faster before O2-independent metabolism begins to play significant role makes what was an anaerobic intensity before now high aerobic Increase ability to sustain as high of a fraction of LT as possible LT Pace Slower/recreational runners: 6-9 sec/km (10-15 sec/mile) slower than 5K race pace (or ~10K race pace) 75-% max HR Highly-trained/competitive runners: sec/km (25-30 sec/mile) slower than 5K race pace (or 9-12 sec/km or sec/mile slower than 10K race pace) 85-90% max HR Subjectively feel comfortably hard LT Workouts Continuous LT Runs 5-7K (3-4 mi) up to 11-13K (7-8 mi) (or ~45 min) LT pace with short periods 4 x 1,600 metres (1 LT pace w/ 1 min LT+ short slightly faster with very short periods 2 sets of 4 x 1, sec/mile faster w/ 45 sec & 2 min between sets LT/LSD Combo Run medium-long runs with LT pace 19-25K (12-16 mi) w/ last 3-6K (2-4 LT pace 3K easy + LT pace + 10K easy + LT pace Blood Lactate Co oncentration (mmol/l) Speed (mph) (or VO 2 (ml/kg/min)) VO2max Work Periods Provides greatest cardiovascular load because you repeatedly reach & sustain maximum stroke volume, cardiac output, & VO2max during work periods. Increase max SV, max CO, & VO2max the higher the VO2max, the higher the aerobic ceiling Recommendations: 3-5 min work periods with 1: 1 work-to- ratio (short intervals with very short, active recovery periods) VO2 (HR) VO2max (HRmax) Recovery Periods Reps 4

5 VO2max Pace Running speed that elicits VO2max Fastest speed that can be maintained for ~7-10 min % max HR Slower/recreational runners: 1,600-metre to 2,400-metre race pace Highly-trained/competitive runners: 3K (2-mile) race pace VO2max Interval Workouts 4 x 1,000 VO2max pace with a 1: 1 work: ratio 6 x 0 VO2max pace with a 1: 1 work: ratio 16 x 400 VO2max pace with a 1:<1 work: ratio If you can run 2,400 metres in 10:00 (= 6:40 mile pace): 4 x 1,000 metres in 4:10 with 3:00 jog recovery 6 x 0 metres in 3:20 with 2:30-3:00 jog recovery 16 x 400 metres in 1:40 with :50 jog recovery Although tempting to run faster when intervals are shorter, pace should be same for all 3 workouts since goal is same to improve VO2max. As you progress, make workouts harder by adding more reps or decreasing recovery period rather than by running faster. Only increase speed of intervals once races have shown that you are indeed faster. Mon Tues Wed Thurs Fri Sat Sun Total Km Mon Tues Wed Thurs Fri Sat Sun Total Km Cycle 3 Week 1 7 km - LT pace w/ 1:00-1:30 14 km 10 km LT Run -6 LT pace 25 km Cycle 4 Week 1 7 km - 4x0 pace w/3:00 jog rec 14 km 7 km sec/km slower 29 km Week 2 7 km - LT pace w/ 1:00-1:30 14 km 10 km LT Run -8 LT pace LT/LSD Combo Run 17 km + 5 LT pace Week 2 9 km - 5x0 pace w/3:00 jog rec 14 km 9 km sec/km slower LT/LSD Combo Run 7 km easy + 5 LT pace + 7 km easy + 5 LT pace Week 3 6 km - LT pace w/ 1:00-1:30 10 km 6 km sec/ km slower 27 km Week 3 5 km - 4x1,000 pace w/ 3:30 jog rec 12 km 8 km sec/km slower 30 km Week 4 10 km 7 km 8 km 17 km LT pace w/1:00-1:30 Note: Cycle 1 includes a gradual increase in kilometres & Cycle 2 includes a continued increase in kilometres with inclusion of one LT workout per week. Exact number of kilometres per week depends on your ability & goals. Week 4 8 km - 3x1,000 pace w/ 3:30 jog rec 7 km 11 km 19 km 53 Taper Purpose of taper is to eliminate fatigue while maintaining fitness. Fitness 40 Linear Research has shown that performance can improve 0.5-6% after tapering. Intensity of training seems to be more important than either training volume (weekly mileage) or frequency. Level Time Fatigue Mileage Step Slow Exponential 10 Fast Exponential Weeks 5

6 Recommendations: Taper Reduce weekly kilometres exponentially. Begin cutting kilometres 2-3 weeks before marathon, with first 70% peak kilometres, second 50%, & week of 35%. Research has shown that reductions in volume up to 60-90% can improve performance, however research is limited to much shorter races that are not as endurance-dependent as marathon. Include some interval training to maintain training intensity. Increase carbohydrate intake ( 70% total calories). Reduce volume of intensity by reducing number of intervals in each workout. Exact length of taper depends on prior training load, level of fatigue, & genetically-predetermined ability to retain training effects while reducing training stimulus. Marathon Taper Mon Tues Wed Thurs Fri Sat Sun Total Km* 5 km 8 km -3 km warmup - 5x1,000 VO2max pace w/3:00 jog recovery -2 km warmdown 3 km 13 marathon pace 4 km -3 km warmup - 4x1,000 LT pace w/ :45-2 km warmdown *Based on pre-taper peak weekly kilometres of. 7 km 5 km 3 km 5 km LT/LSD Combo Run 14 km + 7 LT pace 8 km + 8 marathon pace 7 km 5 km 4 km Marathon (+ marathon) How Not to Get Injured While Training for a Marathon Increase kilometres by no more than 2 km/day/week. If you currently run 32 km in 4 days/week, run no more than 40 km next week by adding 2 km to each of the 4 days. Do not run 40 km next week by adding all 8 km to only 1 day of running. Highly-trained runners can get away with adding more kilometres more quickly, especially if they have experience running more kilometres. Run same kilometres for 3-4 weeks before increasing it. Give legs a chance to adapt to each level of running before increasing the level. Back off training by about 1/3 for 1 recovery week before increasing training load. If you have been running 48 km/week for 3 weeks, back off to 32 km for 1 week before increasing above 48 km for next week. How Not to Get Injured While Training for a Marathon Never increase volume & intensity at same time. When you begin to include speedwork, either drop overall kilometres for week or maintain kilometres from where it was prior to adding speedwork. Never add more kilometres to week at same time as introducing speedwork. Get adequate recovery. All adaptations from training occur during recovery from training, not during training itself. The older you are, the more time you need to recover from training, so the longer you need before increasing volume & intensity. Young runners can get away with training mistakes; older runners cannot. 6