Chapter 24

1. Chapter 24 Exercise at Medium and High Altitude McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

2. The Stress of Altitude • Reduced PO2 creates a metabolic challenge. • Oxygen transport cascade • Progressive change in environment’s oxygen pressure and in various body areas • Oxygen loading at altitude • Saturation of hemoglobin is not influenced until altitudes of ~ 3,048. McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

3. McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

4. Acclimatization • Immediate responses to altitude • Hyperventilation • Increased cardiovascular response • Catecholamine response • Fluid loss • Sensory functions • Myocardial function McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

5. Acclimatization • Longer term adjustments to altitude • Acid–base readjustment • Reduced buffering capacity and the “lactate paradox” • Hematologic changes • Plasma volume decrease • Polycythemia McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

6. Acclimatization • Longer term adjustments to altitude • Cellular adaptations • Capillary adjustments • Increased myoglobin • Increased mitochondrial density • Increased 2,3-DPG levels • Changes in body mass and body composition • Reductions in both lean and fat mass McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

7. McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

8. Acclimatization • Time required for acclimatization • Depends upon altitude • Acclimatization to a specific altitude doesn’t ensure acclimatization to a higher altitude. • 2 to 3 weeks after return to sea level, acclimatization adaptations dissipate. McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

9. Metabolic, Physiologic, and Exercise Capacities at Altitude • Maximal oxygen consumption • Decreases become noticeable at 589 m. • Decreases as altitude increases • Rate of decrease ~ 7 to 9% per 1,000 m McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

10. Metabolic, Physiologic, and Exercise Capacities at Altitude • Circulatory factors • Lowered max HR and SV are not offset by higher hemoglobin levels after acclimatization. • Submaximal exercise • Increased HR offsets decreased SV. • Maximal exercise • Decreased max HR and SV reduce max cardiac output. McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

11. Metabolic, Physiologic, and Exercise Capacities at Altitude • Performance measures • Altitude doesn’t influence events lasting less than 2 minutes. • Events longer than 2 minutes see reduced performance around 1600 m. • Events longer than 20 minutes see reduced performance around 600 – 700 m. McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

12. Aerobic Capacity on Return to Sea Level • Possible negative effects • Residual effects of lost muscle mass • Reductions in max HR and SV McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

13. Altitude Training and Sea-Level Performance • Performance upon return is not improved if using O2max as the criteria • Altitude acclimatization improves ability to perform at altitude. • Decrement in absolute training level at altitude • Athletes cannot train as intensely while at altitude. McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

14. Combine Altitude Stay with Low-Altitude Training • Live high–train low appears to be the best scenario for improving performance. • Capitalize on stress of altitude and acclimatization • Train lower so intensity can be maintained McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

15. At-Home Acclimatization • Methods of simulating hypobaric conditions • Cause altitude-induced physiologic adaptations • Gamow hypobaric chamber • Wallace altitude tent McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

16. McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition