Environmental effects

What is the definition of oxygen debt?

The volume of oxygen consumed posy exercise to return the body to a pre-exercise state

What type of exercise will have a greater EPOC - aerobic or anaerobic?

Anaerobic

How + why is pyruvic acid replenished during recovery?

• converted from lactic acid back to pyruvic acid - to reduce blood acidity

• 50-75% of pyruvic acid is oxidised in the Krebs cycle and ETC

• creates water and carbon dioxide

• 10-25% of pyruvic acid is reconverted to glucose

• small amounts are also converted into protein

What is altitude?

• an area above sea level

• decreased partial pressure of oxygen

Why does ppO₂ decrease at altitude?

• barometric pressure of the air decreases

• percentage oxygen in air remains the same

• but pressure reduces

• this mean air arriving in alveoli has a lower ppO₂

What is the impact of reduction in partial pressure of oxygen?

• reduces the rate of diffusion at the alveoli

• decreases saturation of hemoglobin

• decreased oxygen transportation to the muscles

• reduced diffusion of oxygen into the muscle cell

• increased anaerobic respiration

• increased lactic acid

• earlier onset of fatigue

What are the immediate effects of reduction in partial pressure of oxygen on the body?

• increased breathing rate

• blood plasma volume decreases - increases density of RBCs

• stroke volume decreases - increases HR

• maximum cardiac output decreases at high intensity

• reduced metabolic processes

What is the overall effect of the reduction of ppO₂?

• reduced VO₂ max

• = reduced aerobic capacity

• performance of endurance activities at altitude becomes harder

• demands of the anaerobic energy systems increases

• lactic acid builds

• early fatigue

How much does VO₂ max decrease per 1000m abover 1,500?

around 8-11%

How many days of training are required for performance at 1000-2000m?

3-5 days

How many days of training are required for performance at 2000-3000m?

2 weeks

How many days of training are required for performance at 2000m+ ?

2+ weeks

What is the definition of acclimatisation?

• a process where the athlete gradually adapts to a change in environment

• this is essential for endurance athletes who rely on oxygen transport for effective performance

What are the benefits of altitude training?

• release of EPO increases RBC production

• increased O₂ transport leads to improved oxygen consumption in muscle cell

• breathing rate and ventilation stabilize but remain elevated

• stroke volume and cardiac output reduce as O₂ transport improves

What is the impact of heat on exercise?

• can lead to reduction in performance and illness

• causes body to sweat - can lead to dehydration

• core body temp will rise

What is thermoregulation?

Allows a performer to maintain their core body temp at around 37*C

What happens to the cardiac system when an athlete exercise in heat?

Cardiovascular shift

1. sweating helps to reduce core body temp

2. reduced blood plasma levels

3. increased blood viscosity

4. reduction in venous return

5. reduction in stroke volume

6. increased heart rate

What is hyperthermia?

• rise in core body temp of several degrees

• can lead to respiratory problems such as restriction of airways and increased breathing frequency

What is hyperthermia caused by?

1. prolonged high intensity exercise

2. high air humidity = sweat more

3. high air temperature = lose more water through breath

What is thermal strain?

the combination of cardiovascular drift and hyperthermia

How can an athlete acclimatise pre event?

• train in the heat

• improve hydration

• cooling vests/aids

How does training in heat help the body to acclimatise?

• increases heat tolerance

• increased blood plasma

• decreased sweat

How can an athlete acclimatise during an event?

• cooling aids e.g. vests

• rehydrate

• wear appropriate clothing

• find shade

• pacing and rest intervals

How can an athlete acclimatise to heat after an event?

• isotonic drinks improves hydration

• cooling aids e.g. vests and ice baths

What is the definition of dehydration?

when the body loses more fluids and water than it takes in, leaving it without enough water to function properly

What is the definition of cardiovascular drift?

The upward rise in heart rate that happens during prolonged, steady state exercise even when your pace, power or workload does not change

What is WBGT?

Wet bulb globe temperature

• a composite environmental index used to measure the exact heat stress an athlete experiences while exercising

What is the cardiovascular response to heat?

• Vasodilation

• Sweating

• Heat strain on heart

How does vasodilation help reduce body temp?

• increases blood flow to surface

• increases heat loss by radiation

How does sweating affect the cardiovascular system in response to heat?

• lose water

• decreases blood plasma

• increases blood viscosity

• decreases venous return

• decreases cardiac output

• increases heart rate

What does heat strain on the heart do to the cardiovascular system in response to heat?

Increases blood pressure

What is the overall effect of heat on the cardiovascular system?

Decreased oxygen carrying capacity to muscles / tissues = earlier fatigue

What is the effect of increased breathing frequency as a respiratory response to exercise?

• increased mucus production

• constriction of airways

• decreased oxygen transport

• airways are dry due to heat

• dehydration

= increased cost of exercise

What is the effect of decreased oxygen carrying capacity as a result of heat?

• decreased aerobic production

• increased anaerobic respiration

• increased lactic acid

= earlier fatigue