C H A P T E R 6

1. C H A P T E R 6 METABOLIC ADAPTATIONSTO TRAINING

2. Learning Objectives w Find out how training can maximize the capacity of our energy systems and our potential to perform. w Learn the different muscle adaptations that occur with aerobic and anaerobic training. w Find out how specific types of aerobic and anaerobic training can improve performance.

3. Training Effects on the Skeletal Muscles Aerobic (endurance) training leads to w Improved muscle blood flow, and w Increased capacity of muscle fibers to generate ATP through oxidative metabolism. Anaerobic training leads to w Increased muscular strength and power, and w Increased tolerance for high acid production (low pH) through increased buffering capacity.

4. Individuality of Responses to Aerobic Training of Families and Individuals Twenty weeks of training: bars are families; points within bars are individual family members

5. . w Improved submaximal aerobic endurance and VO2max Adaptations to Aerobic Training w Ultimately, the magnitude of these changes depends on genetic factors

6. Muscular Adaptations to Aerobic Training w Increased cross-sectional area of ST fibers w Conversion of FTb to FTa fibers; there may be a small conversion of FT to ST fibers – this is controversial w Increased number of capillaries around the muscle fibers, which facilitates a greater delivery of oxygen w Increased myoglobin content in the muscle fibers, which allows muscle to store more oxygen and facilitates oxygen diffusion within the fiber to the mitochondria (think seals and whales!) w Increased density of mitochondria in the fibers, and therefore, an increased oxidative enzyme activity

7. . Training Effects on VO2max and SDH Activity (Krebs Cycle Enzyme) Note the difference in % increases in VO2max and SDH activity: this argues against muscle oxidative capacity limiting VO2max.

8. . TRAINING AND VO2MAX

9. CHANGES IN LACTATE THRESHOLD WITH TRAINING

10. Adaptations Affecting Energy Sources w Trained muscles store more glycogen and triglycerides than untrained muscles. w FFAs are better mobilized from muscle and fat cells and more accessible to trained muscles. Increased muscle store of fat Increased delivery because of increased muscle blood flow wMuscles’ ability to oxidize fat increases with training!! wMuscles’ reliance on fat stores conserves glycogen during prolonged exercise!!

11. USE OF ENERGY SOURCES WITH INCREASING INTENSITY

12. TRAINING EFFECT ON OXYGEN DEFICIT Powers and Howley, Exercise Physiology, 2004

13. Adaptations to Anaerobic Training w Increased muscle mass, strength, and power w Slightly increased creatinekinase and glycolyticenzymes; small increases in [ATP] and [PCr] w Improved mechanical efficiency w Increased muscle oxidative capacity (for sprints longer than 30 s) w Increased muscle buffering capacity

14. Changes in Creatine Kinase (CK) with Maximal Anaerobic Training of Different Durations

15. 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.

16. 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.

17. Training Intensity: Power Output/Time w Muscular adaptations are specific to the intensity as well as the volume of training. wAthletes who incorporate high-intensity speed training show more performance improvements than athletes who perform only long, slow, low-intensity training.