1. Scott K. Powers Edward T. Howley Theory and Application to Fitness and Performance SEVENTH EDITION Chapter Copyright ©2009 The McGraw-Hill Companies, Inc. Permission required for reproduction or display outside of classroom use. Exercise and the Environment

2. Chapter 24 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. Outline  Altitude Atmospheric Pressure Short-Term Anaerobic Performance Long-Term Aerobic Performance Maximal Aerobic Performance and Altitude Adaptation to High Altitude Training for Competition at Altitude The Quest for Everest  Heat Hyperthermia  Cold Environmental Factors Insulating Factors Heat Production Descriptive Characteristics Dealing with Hypothermia  Air Pollution Particulate Matter Ozone Sulfur Dioxide Carbon Monoxide

3. Chapter 24 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. Altitude Atmospheric pressure –Decreases at higher altitude Partial pressure –Same percentages of O 2, CO 2, and N 2 in the air –Lower partial pressure of O 2, CO 2, and N 2 Hypoxia: –Low PO 2 (altitude) Normoxia: –Normal PO 2 (sea level) Hyperoxia: –High PO 2 Altitude

4. Chapter 24 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. Effect of Altitude on Performance Short-term anaerobic performance –Lower PO 2 at altitude should have no effect of performance O 2 transport to muscle does not limit performance –Lower air resistance may improve performance Long-term aerobic performance –Lower PO 2 results in poorer aerobic performance Dependent on oxygen delivery to muscle Comparison of performances –1964 Olympics in Tokyo –1968 Olympics in Mexico City Altitude

5. Chapter 24 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. Short Races: 1964 and 1968 Olympics Altitude

6. Chapter 24 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. Long Races: 1964 and 1968 Olympics Altitude

7. Chapter 24 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. A Closer Look 24.1 Jumping Through Thin Air Bob Beamon set new world record for long jump in 1968 Olympic Games in Mexico City –29 feet, 2.5 inches –Lower air density at higher altitude How much was gained at altitude? –Biomechanical calculations indicate only 2.4 cm gained at higher altitude Altitude

8. Chapter 24 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. In Summary  The atmospheric pressure, PO 2, air temperature, and air density decrease with altitude.  The lower air density at altitude offers less resistance to high-speed movement, and sprint performances are either not affected or are improved. Altitude

9. Chapter 24 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. Maximal Aerobic Power and Altitude Decreased VO 2 max at higher altitude –Primarily due to lower oxygen extraction Up to moderate altitudes (~4,000m) –Decreased VO 2 max due to decreased arterial PO 2 At higher elevations –VO 2 max reduction also due to fall in maximum cardiac output Decreased maximal HR at altitude Altitude

10. Chapter 24 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. Changes in VO 2 Max with Increasing Altitude Altitude Figure 24.1

11. Chapter 24 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. Effect of Altitude on Submaximal Exercise Elicits higher heart rate –Due to lower oxygen content of arterial blood Requires higher ventilation –Due to reduction in number of O 2 molecules per liter of air Altitude

12. Chapter 24 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. Effect of Altitude on the Heart Rate Response to Submaximal Exercise Altitude Figure 24.2

13. Chapter 24 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. Effect of Altitude on the Ventilation Response to Submaximal Exercise Altitude Figure 24.3

14. Chapter 24 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. In Summary  Distance-running performances are adversely affected at altitude due to the reduction in the PO 2, which causes a decrease in hemoglobin saturation and VO 2 max.  Up to moderate altitudes (~4,000 m), the decrease in VO 2 max is due primarily to the decrease in arterial oxygen content brought about by the decrease in atmospheric PO 2. At higher altitudes, the rate at which VO 2 max falls may be increased due to a reduction in maximal cardiac output.  Submaximal performances conducted at altitude require higher heart rate and ventilation responses due to the lower oxygen content of arterial blood and the reduction in the number of oxygen molecules per liter of air, respectively. Altitude

15. Chapter 24 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. Adaptation to High Altitude Production of more red blood cells –Higher hemoglobin concentration –Via erythropoietin (EPO) –Counters desaturation caused by lower PO 2 Lifetime altitude residents –Have complete adaptations in arterial oxygen content and VO 2 max In those recently arriving at altitude – Adaptations are less complete Altitude

16. Chapter 24 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. In Summary  Persons adapt to altitude by producing more red blood cells to counter the desaturation caused by the lower PO 2. Altitude residents who spent their growing years at altitude show a rather complete adaptation, as seen in their arterial oxygen content and VO 2 max values. Lowlanders who arrive as adults show only a modest adaptation. Altitude

17. Chapter 24 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. Training for Competition at Altitude Effect of training at altitude on VO 2 max varies among athletes –Due to degree of saturation of hemoglobin Some athletes can improve VO 2 max by training at altitude, others cannot –May be due to training state before arriving at altitude Some athletes have higher VO 2 max upon return to low altitude, while others do not –Could be due to “detraining” effect Cannot train as intensely at altitude Altitude

18. Chapter 24 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. Live High, Train Low Live at high altitude –Elicits an increase in red blood cell mass Via EPO Leads to increase in VO 2 max –≥22 hr/day at 2,000–2,500 m required Or simulated altitude of 2,500–3,000 m for 12–16 hr/day –Intermittent hypobaric hypoxia For example, 3 hr/day, 5 days/wk at 4,000–5,000 m Train at low altitude –Maintain high interval training velocity –Some athletes still experience hemoglobin desaturation Altitude

19. Chapter 24 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. The Winning Edge 24.1 Live High, Train Low Traditionally, increased RBC mass leads to increased VO 2 max Some studies have shown improved VO 2 max without increased RBC mass –With intermittent hypoxia –Potential mechanisms: Improved mitochondrial function Increased buffering capacity This is an area of active debate and research Altitude

20. Chapter 24 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. In Summary  When athletes train at altitude, some experience a greater decline in VO 2 max than others. This may be due to differences in the degree to which each athlete experiences a desaturation of hemoglobin. Remember, some athletes experience desaturation during maximal work at sea level.  Some athletes show an increase in VO 2 max while training at altitude, whereas others do not. This may be due to the degree to which the athlete was trained before going to altitude. Altitude

21. Chapter 24 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. In Summary  In addition, some athletes show an improved VO 2 max upon return to sea level, whereas others do not. Part of the reason may be the altitude at which they train. Those who train at high altitudes may actually “detrain” due to the fact that the quality of their workouts suffers at the high altitudes. To get around this problem, one can alternate low-altitude and sea-level exposures. Altitude

22. Chapter 24 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. The Quest for Everest Mount Everest was first successfully climbed in 1953 –Using supplemental oxygen Climbed without oxygen in 1978 –Previously thought this would be impossible VO 2 max at summit would be just above rest –Actually, VO 2 max estimated at 15 mlkg – 1 min –1 Due to miscalculation of barometric pressure at summit Altitude

23. Chapter 24 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. The Highest Altitudes Attained by Climbers in the 20th Century Altitude Figure 24.4

24. Chapter 24 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. Maximal Oxygen Uptake Measured at a Variety of Altitudes Altitude Figure 24.5

25. Chapter 24 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. Challenges of High-Altitude Climbing Successful climbers have great capacity for hyperventilation –Drives down PCO 2 and H + in blood –Allows more O 2 to bind with hemoglobin at same PO 2 Climbers must contend with loss of appetite –Weight loss –Reduced type I and type II muscle fiber diameter Altitude

26. Chapter 24 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. In Summary  Climbers reached the summit of Mount Everest without oxygen in 1978. This surprised scientists who thought VO 2 max would be just above resting VO 2 at that altitude. They later found that the barometric pressure was higher than they previously had thought and that the estimated VO 2 max was about 15 mlkg –1 min –1 at this altitude.  Those who are successful at these high altitudes have a great capacity to hyperventilate. This drives down the PCO 2 and the [H + ] in blood, and allows more oxygen to bind at the same arterial PO 2. Altitude

27. Chapter 24 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. In Summary  Finally, those who are successful at climbing to extreme altitudes must contend with the loss of appetite that results in a reduction of body weight and in the cross-sectional area of type I and type II muscle fibers. Altitude

28. Chapter 24 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. Heat Hyperthermia –Elevated body temperature Heat-related problems –Heat syncope –Heat cramps –Heat exhaustion May require medical attention –Heat stroke Medical emergency Treatment –Cold water immersion is the most rapid way to lower body temperature Heat

29. Chapter 24 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. Heat-Related Problems Heat

30. Chapter 24 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. Factors Related to Heat Injury Fitness –Higher fitness related to lower risk of heat injury Tolerate more work in heat Acclimatize faster Sweat more –Fit individuals still have risk of heat injury Acclimatization –Exercise in the heat for 10–14 days Low intensity, long duration (<50% VO 2 max, 60–100 min) Moderate intensity, short duration (75% VO 2 max, 30–35 min) –Lower body temperature and HR response –Best protection against heat stroke and exhaustion Heat

31. Chapter 24 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. Factors Related to Heat Injury Hydration –Inadequate hydration increases risk of heat injury –No differences among water, electrolyte drinks, or carbohydrate-electrolyte drinks Environmental temperature –Convection and radiation dependent on gradient between skin and air temperature –High temperature may result in heat gain Clothing –Expose as much skin as possible –Chose materials that “wick” sweat away from skin Heat

32. Chapter 24 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. Factors Related to Heat Injury Humidity (water vapor pressure) –Evaporation is dependent on gradient between skin and air –Relative humidity is a good index of water vapor pressure Metabolic rate –Core temperature is proportional to work rate High work rate increases metabolic heat production Wind –Wind will increase heat loss by convection and evaporation Heat

33. Chapter 24 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. Factors Affecting Heat Injury Heat Figure 24.6

34. Chapter 24 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. Effect of Different Types of Uniforms on Body Temperature Heat Figure 24.7

35. Chapter 24 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. Implications for Fitness Know signs/symptoms of heat illness –Cramps, lightheadedness, etc. Exercise in cooler part of the day Gradually increase exposure to heat/humidity to acclimatize Drink water before, during, and after exercise Wear light clothing Monitor HR and alter exercise intensity –Stay within target heart rate zone Heat

36. Chapter 24 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. Implications for Performance Emphasis on pre-season conditioning –Improve fitness and promote acclimatization Safety during events in high heat/humidity –Cooler time of day, season of the year –Frequent water stops Encourage drinking of 150–300 ml water every 15 minutes –Identification of those with heat illness –Coordinate proper treatment First aid, ambulance services, hospitals –Competitor education Provide information about heat illness Heat

37. Chapter 24 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. In Summary  Heat injury is influenced by environmental factors such as temperature, water vapor pressure, acclimatization, hydration, clothing, and metabolic rate. The fitness participant should be educated about the signs and symptoms of heat injury; the importance of drinking water before, during, and after the activity; gradually becoming acclimated to the heat; exercising in the cooler part of the day; dressing appropriately; and checking the HR on a regular basis. Heat

38. Chapter 24 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. In Summary  Road races conducted in times of elevated heat and humidity need to reflect the coordinated wisdom of the race director and medical director to minimize heat and other injuries. Concerns include running the race at the correct time of the day and season of the year, frequent water stops, traffic control, race monitors to identify and stop those in trouble, and communication between race monitors, medical director, ambulance services, and hospitals.  The heat stress index includes dry bulb, wet bulb, and globe temperatures. The wet bulb temperature, which is a good indicator of the water vapor pressure, is more important than the other two in determining overall heat stress. Heat

39. Chapter 24 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. Cold Hypothermia –Core temperature below 35°C (95°F) 2°C drop associated with maximal shivering 4°C drop associated with ataxia and apathy 6°C drop associated with unconsciousness Further drop associated with ventricular fibrillation, reduced brain blood flow, asystole, death –Heat loss exceeds heat production Conduction, convection, radiation, evaporation Important to protect against heat loss –Maintain core temperature Cold

40. Chapter 24 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. Factors Affecting Hypothermia Cold Figure 24.8

41. Chapter 24 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. Environmental Factors Temperature –Gradient for convective heat loss Vapor pressure –Low water vapor pressure encourages evaporation Wind –Rate of heat loss influenced by wind speed –Windchill index “Effective” temperature Water immersion –Rate of heat loss 25x greater than air of same temperature Cold

42. Chapter 24 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. Wind Chill Chart Cold

43. Chapter 24 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. Effect of Water Temperature on Survival Cold Figure 24.9

44. Chapter 24 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. In Summary  Hypothermia is influenced by natural and added insulation, environmental temperature, vapor pressure, wind, water immersion, and heat production.  The wind chill index describes how the wind lowers the effective temperature at the skin such that convective heat loss is greater than what it would be in calm air at that same temperature.  Water causes heat to be lost by convection twenty- five times faster than it would be by exposure to air of the same temperature. Cold

45. Chapter 24 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. Insulating Factors Subcutaneous fat –Especially effective in cold water Clothing –Clo units 1 clo is insulation needed to maintain core temperature at rest at 21°C, 50% RH, and 6 mmin –1 wind Increased clothing required in cold, wet, windy conditions Dry clothing more effective than wet Amount of insulation required is lower during exercise Cold

46. Chapter 24 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. Heat Production Heat production increases upon exposure to cold –Inverse relationship between VO 2 and body fatness Earlier onset of shivering in lean men Resting VO 2 and core temperature maintained in “fat” men in cold water Increased VO 2 and decreased core temperature in “thin” men Fuel use –Fat is primary fuel for shivering –Shivering can lead to muscle glycogen depletion Cold

47. Chapter 24 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. Descriptive Characteristics Influencing Responses to Cold Exposure Gender –At rest, women show faster reduction in body temperature then men –In cold water, decrease in body temperature similar in men and women –Differences can be explained by body composition and anthropometry Age –Older (>60 years) less tolerant to cold –Children experience faster fall in body temperature Cold

48. Chapter 24 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. Changes in Insulation Requirement at Different Temperatures and Activities Cold Figure 24.10

49. Chapter 24 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. In Summary  Subcutaneous fat is the primary “natural” insulation and is very effective in preventing rapid heat loss when a person is exposed to cold water.  Clothing extends this insulation, and the insulation value of clothing is described in clo units, where a value of 1 describes what is needed to maintain core temperature while sitting in a room set at 21°C and 50% RH with an air movement of 6 msec –1. Cold

50. Chapter 24 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. In Summary  The amount of insulation needed to maintain core temperature is less when one exercises because the metabolic heat production helps maintain the core temperature. Clothing should be worn in layers when exercising so one can shed one insulating layer at a time as body temperature increases.  Heat production increases on exposure to cold, with an inverse relationship between the increase in VO 2 and body fatness. Women cool faster than men when exposed to cold water, exhibiting a longer delay in the onset of shivering and a lower VO 2, despite a greater stimulus to shiver. Cold

51. Chapter 24 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. Dealing with Hypothermia Effects of hypothermia –Reduced coordination –Slurred speech –Impaired judgment Treatment of hypothermia –Get person out of cold, wind, and rain –Remove all wet clothing –Provide warm drinks and dry clothing –Put person into sleeping bag With another person, if semiconscious –Find a source of heat Cold

52. Chapter 24 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. In Summary  If a person becomes hypothermic, get the person out of the wind, rain, and cold; remove wet clothing and put on dry clothing; use a sleeping bag for warmth; and if it is an extreme case, remove clothing from the person and have another person in the sleeping bag to provide warmth; finally, provide some source of heat. Cold

53. Chapter 24 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. Air Pollution Variety of gases and particulates Have detrimental effect on health and performance –Decrease capacity to transport oxygen –Increase airway resistance –Alter perception of effort Physiological response depends on: –Amount or “dose” received Concentration in air Duration of exposure Volume of air inhaled –Increases during exercise Air Pollution

54. Chapter 24 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. Air Pollution Particulate matter –Promote pulmonary infection –Elevate blood pressure, reduce fibrinolysis, reduce vasodilation –Cause oxidative stress and DNA damage Ozone –Decreases VO 2 max and respiratory function Sulfur dioxide –Causes bronchoconstriction in asthmatics Carbon monoxide –Binds to hemoglobin and reduces oxygen transport –Affects submaximal exercise and VO 2 max Air Pollution

55. Chapter 24 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. Effect of Carbon Monoxide on VO 2 Max Air Pollution Figure 24.11

56. Chapter 24 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. Preventing Air Pollution Problems Reduce exposure time –Effects are dose-dependent Stay away from “bolus” amounts of pollutants –Smoking areas, high-traffic areas, urban areas Do not exercise during most polluted parts of day –7–10 a.m., 4–7 p.m. Monitor the air quality index (AQI) –Measure of five pollutants Ozone, particulate matter, CO, SO 2, and NO 2 –AQI scale runs from 0–500 Air Pollution

57. Chapter 24 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. Air Quality Index Figure 24.12 Air Pollution

58. Chapter 24 Copyright ©2009 The McGraw-Hill Companies, Inc. All Rights Reserved. In Summary  Air pollution can affect performance. Exposure to ozone decreases VO 2 max and respiratory function, while sulfur dioxide causes bronchoconstriction in asthmatics.  Carbon dioxide binds to hemoglobin and reduces oxygen transport in much the same way that altitude does.  To prevent problems associated with pollution of any type, reduce exposure time; stay away from “bolus” amounts of the pollutant; and schedule activity at the least polluted part of the day.  The Air Quality Index should be monitored to determine if conditions are safe for exercising outdoors. Air Pollution