Lecture 9 (Environmental Physiology)
-
Upload
helmi-rais -
Category
Documents
-
view
226 -
download
0
Transcript of Lecture 9 (Environmental Physiology)
-
8/12/2019 Lecture 9 (Environmental Physiology)
1/30
-
8/12/2019 Lecture 9 (Environmental Physiology)
2/30
(c) 2004 The McGraw-Hill Companies, Inc. All rights reserved.
Objectives
Describe the changes in atmospheric pressure, air temperature,
and air density with increasing altitude
Describe how altitude affects sprint performances and explain
why that is the case
Explain why distance running performance decrease at altitude
Draw a graph to show effect of altitude on VO2 MAXand list
reasons for this response
Graphically describe effect of altitude on the HR and ventilation
responses to submaximal work, and explain why these changes
are appropriate
-
8/12/2019 Lecture 9 (Environmental Physiology)
3/30
(c) 2004 The McGraw-Hill Companies, Inc. All rights reserved.
Objectives
Describe the process of adaptation to altitude, and the degree to
which this adaptation can be complete
Explain why such variability exists among athletes in the
decrease in VO2 MAXupon exposure to altitude, the degree of
improvement in VO2 MAXat altitude, and the gains made uponreturn to sea level
Describe potential problems associated with training at high
altitude and how one might deal with them
Explain the circumstances that caused physiologists to
reevaluate their conclusions that humans could not climb MountEverest without oxygen
-
8/12/2019 Lecture 9 (Environmental Physiology)
4/30
-
8/12/2019 Lecture 9 (Environmental Physiology)
5/30
(c) 2004 The McGraw-Hill Companies, Inc. All rights reserved.
Objectives
List the factors influencing hypothermia
Explain what Windchill Index is relative to
heat loss Explain why exposure to cold water is more
dangerous than exposure to air of the
same temperature
-
8/12/2019 Lecture 9 (Environmental Physiology)
6/30
(c) 2004 The McGraw-Hill Companies, Inc. All rights reserved.
Objectives
Describe the role of subcutaneous fat andenergy production in the development ofhypothermia
List the steps to follow to deal withhypothermia
Explain how carbon monoxide can
influence performance, and list the stepsthat should be taken to reduce the impactof pollution on performance
-
8/12/2019 Lecture 9 (Environmental Physiology)
7/30(c) 2004 The McGraw-Hill Companies, Inc. All rights reserved.
Altitude
Atmospheric pressure
Decreases at higher altitude
Partial pressure Same percentages of O2, CO2, and N2in the
air
Lower partial pressure of O2, CO2, and N2
Hypoxia: low PO2(altitude)
Normoxia: normal PO2(sea level)
Hyperoxia: high PO2
-
8/12/2019 Lecture 9 (Environmental Physiology)
8/30(c) 2004 The McGraw-Hill Companies, Inc. All rights reserved.
Effect of Altitude onPerformance
Short-term anaerobic performance
Lower PO2at altitude should have no effect of
performance
Lower air resistance may improve performance
Long-term aerobic performance
Lower PO2results in poorer aerobic
performance
-
8/12/2019 Lecture 9 (Environmental Physiology)
9/30(c) 2004 The McGraw-Hill Companies, Inc. All rights reserved.
Effect of Altitude on VO2max
Decreased VO2maxat higher altitude
Up to moderate altitudes (~4,000m)
Decreased VO2maxdue to decreased arterialPO2
At higher elevations
Rate of VO2maxreduction also due to fall in
maximum cardiac output
-
8/12/2019 Lecture 9 (Environmental Physiology)
10/30(c) 2004 The McGraw-Hill Companies, Inc. All rights reserved.
Changes in VO2maxWithIncreasing Altitude
Fig 24.1
-
8/12/2019 Lecture 9 (Environmental Physiology)
11/30
(c) 2004 The McGraw-Hill Companies, Inc. All rights reserved.
Effect of Altitude onSubmaximal Exercise
Elicits higher heart rate
Due to lower oxygen content of arterial blood
Requires higher ventilation Due to reduction in number of O2molecules
per liter of air
-
8/12/2019 Lecture 9 (Environmental Physiology)
12/30
(c) 2004 The McGraw-Hill Companies, Inc. All rights reserved.
Effect of Altitude on SubmaximalHeart Rate Response
Fig 24.2
-
8/12/2019 Lecture 9 (Environmental Physiology)
13/30
(c) 2004 The McGraw-Hill Companies, Inc. All rights reserved.
Effect of Altitude on SubmaximalVentilation Response
Fig 24.3
-
8/12/2019 Lecture 9 (Environmental Physiology)
14/30
(c) 2004 The McGraw-Hill Companies, Inc. All rights reserved.
Adaptation to High Altitude
Production of more red blood cells
Counter desaturation caused by lower PO2
In those who grew up at altitude Have complete adaptations in arterial oxygen
content and VO2max
In those recently arriving at altitude
Adaptations are less complete
-
8/12/2019 Lecture 9 (Environmental Physiology)
15/30
(c) 2004 The McGraw-Hill Companies, Inc. All rights reserved.
Training for Competition at Altitude
Effect of training at altitude on VO2maxvaries betweenathletes
Due to degree of saturation of hemoglobin
Some athletes can improve VO2max
by training ataltitude, others cannot
May be due to training state before arriving ataltitude
Some athletes have higher VO2maxupon return to low
altitude, while others do not Could be due to detraining effect
Cannot train as intensely at altitude
-
8/12/2019 Lecture 9 (Environmental Physiology)
16/30
(c) 2004 The McGraw-Hill Companies, Inc. All rights reserved.
The Quest for Everest
Mount Everest was climbed without oxygen
in 1978
Previously thought that VO2max
at summit
would be just above rest
Actually, VO2maxestimated at 15 mlkg-1min-1
Due to miscalculation of barometric pressure at
summit
-
8/12/2019 Lecture 9 (Environmental Physiology)
17/30
(c) 2004 The McGraw-Hill Companies, Inc. All rights reserved.
Challenges ofHigh Altitude Climbing
Successful climbers have great capacity for
hyperventilation
Drives down PCO2and H+in blood
Allows more O2to bind with hemoglobin at
same PO2
Climbers must contend with loss of appetite
Results in loss of weight
Reduction muscle fiber diameter
-
8/12/2019 Lecture 9 (Environmental Physiology)
18/30
(c) 2004 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
-
8/12/2019 Lecture 9 (Environmental Physiology)
19/30
(c) 2004 The McGraw-Hill Companies, Inc. All rights reserved.
Factors Affecting Heat Injury
Fig 24.6
-
8/12/2019 Lecture 9 (Environmental Physiology)
20/30
(c) 2004 The McGraw-Hill Companies, Inc. All rights reserved.
Consideration for Exercise
Know signs/symptoms of heat illness
Exercise in cooler part of the day
Gradually increase exposure to heat toacclimatize
Drink water before, during, and after
exercise
Wear light clothing
Alter exercise intensity to stay within THR
zone
-
8/12/2019 Lecture 9 (Environmental Physiology)
21/30
(c) 2004 The McGraw-Hill Companies, Inc. All rights reserved.
Implications for Performance
Safety during events in high heat/humidity
Time of day, season of the year
Frequent water stops
Traffic control
Identification of those with heat illness
Coordinate proper treatment
First aid, ambulance services, hospitals
-
8/12/2019 Lecture 9 (Environmental Physiology)
22/30
-
8/12/2019 Lecture 9 (Environmental Physiology)
23/30
(c) 2004 The McGraw-Hill Companies, Inc. All rights reserved.
Cold
Important to protect against heat loss Maintain core temperature
The windchill index Describes how wind lowers the effective
temperature at the skin
Water
Causes heat loss by convection 25 timesgreater than in air
-
8/12/2019 Lecture 9 (Environmental Physiology)
24/30
(c) 2004 The McGraw-Hill Companies, Inc. All rights reserved.
Hypothermia Insulating factors Subcutaneous fat
Clothing
Amount of insulation required is lowerduring exercise
Environmental factors Temperature
Vapor pressure Wind
Water immersion
Energy production
-
8/12/2019 Lecture 9 (Environmental Physiology)
25/30
(c) 2004 The McGraw-Hill Companies, Inc. All rights reserved.
Insulation in the Cold
Insulation Subcutaneous fat
Clothing
Amount of insulation needed is lowerduring exercise
Energy production increases uponexposure to cold Inverse relationship between VO2and
body fatness
Women cool faster than men
-
8/12/2019 Lecture 9 (Environmental Physiology)
26/30
(c) 2004 The McGraw-Hill Companies, Inc. All rights reserved.
Factors Affecting Hypothermia
Fig 24.9
-
8/12/2019 Lecture 9 (Environmental Physiology)
27/30
(c) 2004 The McGraw-Hill Companies, Inc. All rights reserved.
Effect of WaterTemperature on Survival
Fig 24.9
-
8/12/2019 Lecture 9 (Environmental Physiology)
28/30
(c) 2004 The McGraw-Hill Companies, Inc. All rights reserved.
Changes in
InsulationRequirement atDifferentTemperaturesand Activities
Fig 24.10
-
8/12/2019 Lecture 9 (Environmental Physiology)
29/30
(c) 2004 The McGraw-Hill Companies, Inc. All rights reserved.
Air Pollution
Ozone
Decreases VO2maxand respiratory function
Sulfur dioxide
Causes bronchoconstriction in asthmatics Carbon monoxide
Binds to hemoglobin and reduces oxygen transport
Prevention of problems
Reduce exposure time Stay away from bolus amounts of pollutants
Exercise during least polluted part of day
-
8/12/2019 Lecture 9 (Environmental Physiology)
30/30
(c) 2004 The McGraw Hill Companies Inc All rights reserved
Effect of CarbonMonoxide on VO2max
Fig 24.11