A.1.2.2 Acute and Chronic Responses to the Environment (HL)

What are the three main stressors (environments) the body seeks to counteract?

1. Heat

2. Cold

3. Altitude

What is acclimatization? Give an example

the natural adaptations in an environment e.g. training in the Alps to acclimatize to the altitude

What is acclimation? Give an example

the acclimatization in an artificial environment e.g. an environmental chamber

What is heat acclimatization?

exercise in a hot environment

How long does it take to acclimatize to the heat?

10-14 days

How long should the exposure be for the heat acclimatization?

90-100min

What has to be gradual as you continue to acclimatize to the heat?

intensity and duration

What are some acute adaptations during submaximal exercise in the heat?

• lower HR

• lower core body temperature

• higher sweat rate

What are some chronic adaptations during submaximal exercise in the heat?

• increased plasma volume

• earlier onset of sweating

• reduction of electrolyte use

• decreased psychological perception of effort

What is a major risk during exercise in hot/humid environments?

hyperthermia

What is hyperthermia?

when the core body temperature is much higher than normal

What can provide protection from heat stress during exercise in the heat?

aerobic fitness

What are the benefits of this aerobic fitness?

• improved sweating response

• initiation of sweating at a lower core temp

• greater sensitivity of sweating response to increasing core temp

What are the effects of hyperthermia?

• impairs the level of the maximal force generation

• impairs mental activity

How can an athlete lessen the effects on heat performance?

pre-cooling before exercise

How can an athlete pre-cool before an exercise?

training with an ice vest

What does the ice vest do?

delays heat build up during warm-ups, decreasing the perception of heat stress

What are the main factors of cold stress in cold environments?

air temperature and wind speed

What is attempted to be avoided in these cold environments?

hypothermia

What is hypothermia?

low body temperature, different clinical categories

What are some of the warning signs of hypothermia?

• uncontrollable shivering

• slurred speech

• stumbling

• drowsiness

What are some acute adaptations to cold exposure?

• vasoconstriction (skin and skeletal muscles)

• shivering

What are the characteristics of shivering?

• involuntary, repeated muscle contractions

• immediate/several minutes after cold exposure

• minimal movement

• higher intensity = more muscles

What happens during exercise in the cold?

lower HR due to decreased activity in the nervous system, increase SV/maintain CO

What is further required as a result of shivering?

more energy to facilitate the muscle contractions (fats/lipids)

What are some chronic adaptations to cold exposure?

• habituation

• metabolic acclimatization

• insulative acclimatization

What is habituation?

desensitization of normal responses to the cold

What is metabolic acclimatisation?

greater shivering response to increase heat production

What is insulative acclimatization?

increased vasoconstriction to enhance heat conservation

What are the health risks of exercising in the cold?

1. Hypothermia

2. Frostbite

3. Frostnip

Frostbite

muscle tissues freeze,

What is at most risk to frost bite?

body’s outer extremities (fingers, toes, nose)

Frostnip

initial freezing of skin tissue, not long-term damage

What is a CLO unit?

value that describes the degree of insulation provided by the clothing you wear

What is barometric pressure?

pressure of the Earths atmosphere pressing down on us

What is there a lack of at high altitudes?

oxygen

What is a hypoxic environment?

where this an insufficient amount of oxygen to maintain normal tissue function

Every 150m of ascent…

air temperature decreases by 1°C

What are some acute adaptations to altitude exposure?

• increased breathing rate (TD and RR increase)

• increase HR = increase cardiac output

• plasma volume decrease

• basal metabolic rate increases but appetite decreases

What are some chronic adaptations to altitude exposure?

• increased red blood cell production (erythroprotein)

• weight loss and changes in body composition

• increased capillary density

• increased lung capacity

what is arterial oxygen saturation?

the degree to which oxygen is bound to hemoglobin in the blood, measured as a percentage