Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Chapter 24 Exercise at Medium and High Altitude
Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition The Stress of Altitude Reduced P O 2 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.
Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition
Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Acclimatization Immediate responses to altitude –Hyperventilation –Increased cardiovascular response –Catecholamine response –Fluid loss Sensory functions Myocardial function
Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Acclimatization Longer term adjustments to altitude –Acid–base readjustment Reduced buffering capacity and the “lactate paradox” –Hematologic changes Plasma volume decrease Polycythemia
Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition 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
Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition
Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition 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.
Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition 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
Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition 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.
Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition 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.
Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Aerobic Capacity on Return to Sea Level Possible negative effects –Residual effects of lost muscle mass –Reductions in max HR and SV
Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition Altitude Training and Sea-Level Performance Performance upon return is not improved if using O 2max 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.
Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition 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
Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition At-Home Acclimatization Methods of simulating hypobaric conditions –Cause altitude-induced physiologic adaptations Gamow hypobaric chamber Wallace altitude tent
Copyright © 2007 Lippincott Williams & Wilkins.McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition