METABOLIC ADAPTATIONS TO EXERCISE

1. CHAPTER 6 CHAPTER 6 METABOLIC ADAPTATIONSTO EXERCISE METABOLIC ADAPTATIONSTO EXERCISE

2. Learning Objectives w Find out how training can maximize our energy systems and our potential to perform. w Learn the differing adaptations that occur with aerobic and anaerobic training. w Find out how specific types of aerobic and anaerobic training can improve performance. w Discover the best way to monitor changes in training.

3. Aerobic vs Anaerobic Training Aerobic (endurance) training leads to w Improved blood flow, and w Increased capacity of muscle fibers to generate ATP. Anaerobic training leads to w Increased muscular strength, and w Increased tolerance for acid-base imbalances during highly intense effort.

4. . w Improved submaximal aerobic endurance and VO2max Adaptations to Aerobic Training w Muscular changes in fiber size, blood and oxygen supply, and efficiency of functioning w Improved efficiency of energy production

5. Muscular Adaptations w Increased size of ST fibers w Increased number of capillaries supplying the muscles w Increased myoglobin content of muscle (allowing muscle to have more oxygen) w Increased number, size, and oxidative enzyme activity of mitochondria

6. SDH ACTIVITY IN THE DELTOID

7. LEG MUSCLE ENZYME ACTIVITIES

8. Adaptations Affecting Energy Sources w Trained muscles store more glycogen and triglycerides than untrained muscles. w FFAs are better mobilized and more accessible to trained muscles. w Muscles’ ability to oxidize fat increases with training. w Muscles’ reliance on fat stores first conserves glycogen during prolonged exercise.

9. USE OF ENERGY SOURCES WITH INCREASING INTENSITY

10. w Myoglobin (which stores oxygen) content increases in muscle by about 75% to 80% with aerobic training. (continued) Key Points Adaptations to Aerobic Training w Aerobic training stresses ST fibers more than FT fibers and causes ST fibers to increase in size (but not in percentage). w Prolonged aerobic training may cause FTb fibers to take on characteristics of FTa fibers. w The number of capillaries supplying each muscle fiber increases with training.

11. Key Points Adaptations to Aerobic Training w Aerobic training increases the number and size of mitochondria and the activities of oxidative enzymes. w Endurance-trained muscle stores more glycogen and triglyceride than untrained muscle. w Increased fat availability and capacity to oxidize fat lead to increased use of fat as an energy source, sparing glycogen.

12. Volume w Frequency of exercise bouts w Duration of each exercise bout Intensity w Interval training w Continuous training Aerobic Training Considerations

13. . . QO2 vs VO2max . QO2 measures the maximal respiratory or oxidative capacity of muscle. . VO2max measures the body's maximal oxygen uptake.

14. . . QO2 AND VO2MAX WITH TRAINING

15. w Athletes who train with progressively greater workloads eventually reach a maximal level of improvement beyond which additional training volume will not improve endurance or VO2max. . Training Volume w Volume is the load of training in each training session and over a given period of time. w Adaptations to given volumes vary from individual to individual. w An ideal aerobic training volume appears to be equivalent to an energy expenditure of about 5,000 to 6,000 kcal per week.

16. . TRAINING VOLUME AND VO2MAX

17. Training Intensity w Muscular adaptations are specific to the speed as well as duration of training. w Athletes who incorporate high-intensity speed training show more performance improvements than athletes who perform only long, slow, low-intensity training. w Aerobic intervals are repeated, fast-paced, brief exercise bouts followed by short rests. w Continuous training involves one continuous, high-intensity exercise bout.

18. Adaptations to Anaerobic Training w Increased muscular strength w Slightly increased ATP-PCr and glycoytic enzymes w Improved mechanical efficiency w Increased muscle oxidative capacity (for sprints longer than 30 s) w Increased muscle buffering capacity

19. Did You Know…? Performance improvements after anaerobic training (short, high-intensity training) appear to be related more to muscular strength gains than improvements in the anaerobic yield of ATP through the ATP-PCr and glycolytic systems.

20. Muscle Buffering Capacity w Anaerobic training improves muscle buffering capacity, but aerobic training does little to increase the muscles' capacity to tolerate sprint-type activities. w Improved muscle buffering capacity allows sprint-trained athletes to generate energy for longer periods before fatigue limits the contractile process.

21. Selected Muscle Enzyme Activities (mmol g min ) for Untrained, Anaerobically Trained, and Aerobically Trained Men . . -1 -1 Anaerobically Aerobically Untrained trained trained Aerobic enzymesOxidative systemSuccinate dehydrogenase 8.1 8.0 20.8Malate dehydrogenase 45.5 46.0 65.5Carnitine palmityl transferase 1.5 1.5 2.3 Anaerobic enzymesATP-PCr systemCreatine kinase 609.0 702.0 589.0Myokinase 309.0 350.0 297.0Glycolytic systemPhosphorylase 5.3 5.8 3.7Phosphofructokinase 19.9 29.2 18.9Lactate dehydrogenase 766.0 811.0 621.0 a a a a a a a a Denotes a significant difference from the untrained value.

22. Key Points Adaptations to Aerobic Training w Ideal aerobic training volume is equivalent to a caloric expenditure of 5,000 to 6,000 kcal per week. w To perform at higher intensities, athletes must train at higher intensities. w Aerobic interval training—repeated bouts of short, high-intensity performance followed by short rest periods—and continuous training—one prolonged, high-intensity bout—both help generate aerobic benefits.

23. Key Points Adaptations to Anaerobic Training w Anaerobic training improves anaerobic performance mostly as a result of strength gains. w Anaerobic training improves efficiency of movement and thus reduces the energy expended for that movement. w Bouts of anaerobic training lasting beyond 30 s rely on oxidation for energy; muscle aerobic capacity can be improved with this type of training. w Anaerobic training increases muscle buffering capacity, thus delaying fatigue.

24. . w Repeated measurements of VO2max Methods of Monitoring Training Changes w Lactate threshold tests w Comparing lactate values taken after steady-state exercise at various times in the training period

25. EXERCISE INTENSITY AND BLOOD LACTATE ACCUMULATION

26. TRAINING AND BLOOD LACTATE CONCENTRATION

27. Did You Know…? The most practical and simplest protocol for monitoring training appears to be comparing single blood lactate values taken after a fixed-pace activity at various times during a training period. As you become better trained, your blood lactate concentration is lower for the same rate of work.