Metabolic Adaptations to Training Chapter 5

1. Metabolic Adaptations to TrainingChapter 5 • Aerobic training: • increases number of capillaries per muscle fiber • increasesand the number of capillaries for a given cross-sectional area of muscle • Both of these changes improve blood perfusion in the muscles.

2. Fiber Types • Type I – ST – Red – Aerobic – Fatigue Resistant – Few Fibers per Motor Unit • Type IIa– FTO – Pink – Anaerobic w/aerobic capability • Type IIb– FTG – White – Purely Anaerbobic - Multiple Fibers per Motor Unit – Power Fibers

3. Response and Adaptation • Endurance training stresses ST muscle fibers more than FT fibers. • Result - ST fibers enlarge with training. • Hunters

4. Response and Adaptation • Percentages of ST and FT fibers do not appear to change • Endurance training causes Ftb fibers to take on more Fta characteristics.

5. Response and Adaptation • Endurance training increases muscle myoglobin content by about 75% to 80% • Myoglobin stores oxygen.

6. Response and Adaptation • Endurance training increases both the number and the size of the mitochondria. • Activities of many oxidative enzymes are increased with training.

7. Response and Adaptation • These changes occurring in the muscles, combined with adaptations in the oxygen transport system, lead to enhanced functioning of the oxidative system and improved endurance.

8. Fuel Storage • Endurance-trained muscle stores considerably more glycogen than does untrained muscle. • Endurance-trained muscle also stores more fat (triglyceride) than does untrained muscle.

9. Fuel Storage • The activities of many enzymes involved in b oxidation of fat increase with training, thus free fatty acid levels increase. • This leads to increased use of fat as an energy source, sparing glycogen.

10. Training • The ideal training regimen should have a caloric expenditure of a minimum of 2,000 to a maximum of about 5,000 to 6,000 kcal per week. • There seems to be little benefit beyond this level in consideration of the added risk of injury.

11. Training • Intensity is also a critical factor in improving performance. • Adaptations are specific to the speed and duration of training bouts, so those who perform at higher intensities must train at higher intensities.

12. Training • Aerobic interval training involves repeated bouts of high-intensity performance separated by brief rest periods.

13. Training • This training, although traditionally considered only anaerobic, generates aerobic benefits because the rest period is so brief that full recovery can’t occur, thus the aerobic system is stressed.

14. Training • Continuous training is done as one prolonged bout of exercise, some many exercisers find it boring.

15. Training • The aerobic benefits from both interval training and continuous high-intensity training seem to be about the same.

16. Anaerobic Training • Anaerobic training bouts improve anaerobic performance, but the improvement appears to result more from strength gains than from improvements in the functioning of the anaerobic energy systems.

17. Anaerobic Training • Anaerobic training also improves the efficiency of movement, and more efficient movement requires less energy expenditure.

18. Anaerobic Training • Although sprint-type exercise is anaerobic by nature, part of the energy used during longer sprint bouts comes from oxidation, so muscle aerobic capacity can also be increased with this type of training.

19. Anaerobic Training • Muscle buffering capacity is increased by anaerobic training, allowing the achievement of higher muscle and blood lactate levels. • This allows the H+ that dissociates from the lactic acid to be neutralized, thus delaying fatigue.

20. Anaerobic Training • Changes in muscle enzyme activity are highly specific to the type of training.