1.4 Environmental Effects

EPOC

• Excess Post Exercise Oxygen Consumption

  • the volume of oxygen consumed post-exercise to return the body to a pre-exercise state

After exercise

• Myoglobin has lost its stores of oxygen

• ATP, PC, and glycogen stores are depleted

• Lactic acid levels are high

Aims of recovery

• Primary aim is to return the body to a pre-exercise state where all stores of fuels are complete, and blood and muscle tissue are free from bi-products

• Energy is required to do this, and so aerobic energy production continued - EPOC - also known as oxygen debt

Fast Alactacid Component

• PC stores replenished

  • 3 minutes to fully recover

  • 30 seconds for 50%

  • 60 seconds for 75%

• Blood and muscle oxygen is replenished

  • Within 1 minute, oxygen resaturates the bloodstream - associates with haemoglobin

  • Within 3 minutes, the oxygen link to muscle cells is restored

Slow Lactacid Component

needs 5-8 litres of O2

- takes hours to complete

• Elevated ventilation and circulation

  • Respiratory rate, depth, and HR remain elevated - gradually decrease to maximise O2 delivery, and bi-product removal

• Elevated body temperature

  • Increases metabolic rate - 60-70% of the slow lactacid component

• Removal of lactic acid

  • 50-75% is converted back into pyruvic acid and used in the Kreb’s Cycle

  • 10-25% is converted back to glucose

  • Can be converted to proteins by the Cori Cycle

  • Can be removed via sweating and in urine

Effects on recovery

• Warm Up = minimise time spent using anaerobic aerobic system - reduces oxygen deficit

• Active Recovery = maintains respiratory rate, and HR -  speeds up the removal of lactic acid

• Cooling Aids = used post-event to speed up the removal of lactic acid and to reduce muscle soreness and DOMS - ice baths

• Intensity of Training = high intensity training will increase ATP/PC storage - boosts efficiency of the fast component, increases tolerance of lactic acid and buffering capacity, and delays OBLA - reduces demand on the slow component. Low intensity exercise will increase aerobic capacity - delays OBLA - maximises oxygen delivery to working muscles - higher intensity takes longer to recover, and low intensity allows for a faster recovery

• Work:Relief Ratios = can maximise recovery - 1:1 /1:2 / 1:3

• Strategies and Tactics = using time-outs and substitutions - delays OBLA and fatigue

• Nutrition = maximise fuel stores - delays fatigue - reduces lactic acid - speeds up recovery - creatine supplements

Altitude

the height or elevation above sea level - effects of altitude occur after 1500m

Barometric pressure

the pressure exerted by the Earth’s atmosphere at any given point - mmHg

Increase in altitude =

• decrease in barometric pressure:

  • Air gets thinner

  • Less oxygen in the air

  • Less oxygen gets diffused into blood - smaller diffusion gradient

Diffusion gradients

• sea level = 159mmHg - diffusion gradient = 119 to capillary blood

• 3600m = 105mmHg - diffusion gradient = 65 to capillary blood

• 8800m (Everest) = 43mmHg - diffusion gradient = 3 to capillary blood

Effects of altitude on the body

• Blood volume decreases - plasma reduces by 25% - increases RBC density - allows easier diffusion

• Stroke volume decrease - heart rate increased - compensates for stroke volume decrease

• CO, SV, and HR decrease during maximal intensity exercise

• Overall intensity and performance decreases - less oxygen gets to the muscles

Acclimitisation

a process of gradual adaptation to a change in environment - e.g a lower partial pressure of oxygen

Acclimatisation periods

a process of gradual adaptation to a change in environment - e.g a lower partial pressure of oxygen

Acclimatisation periods:

• 1000-2000m = 3-5 days

• 2000-3000m = 1-2 weeks

• 3000m+ = 2+ weeks - should gradually increase altitude to decrease altitude sickness

• extreme altitudes (5000m+) = 4+ weeks - e.g Everest

Benefits of acclimatisation

a process of gradual adaptation to a change in environment - e.g a lower partial pressure of oxygen

Acclimatisation periods:

• 1000-2000m = 3-5 days

• 2000-3000m = 1-2 weeks

• 3000m+ = 2+ weeks - should gradually increase altitude to decrease altitude sickness

• extreme altitudes (5000m+) = 4+ weeks - e.g Everest

Benefits:

• increase in RBC production - body produces more EPO

• breathing rate stabilises - does remain higher than at sea level

• SV and CO reduce - oxygen diffusion becomes more efficient

• reduced headaches, sickness, breathlessness, and better sleep

Thermoregulation

• process of maintaining internal core temperature 

Thermoreceptors

• sensory receptors which detect a change in temperature and relay information to the brain

How thermoreceptors work

• Thermoreceptors sense a change in body temperature

• If body temperature rises, metabolic heat is transported by the circulating blood to the surface of the body, and released mostly by convection and evaporation

• An athlete exercising in the heat can lose 2-3 litres of water per hour

• Loss of water causes decreased blood volume and dehydration

• The rate of heat loss through sweating is impacted by the humidity

Hyperthermia

• significantly raised core body temperature

Causes of hyperthermia

• high and prolonged exercise intensities

• high air temperature

• high relative humidity

Cardiovascular drift

• upwards drift in heart rate associated with a rise in body temperature - 1° C increases heart rate by 10 bpm

Effect of heat on the cardiovascular system

• Dilatation of arterioles

  • increased blood flow and blood pooling in the limbs

• Decreased blood volume, venous return, and blood pressure

  • increased HR

  • increased strain on cardiovascular system

  • reduced O2 transport to working muscles

Effect of heat on the respiratory system

• Dehydration can dry airways and make breathing difficult

  • increased mucus production

  • constriction of the airways

  • decreased volume of air for gaseous exchange

• Increased breathing frequency to maintain oxygen consumption

  • increased oxygen cost of exercise

• High levels of sunlight can increase pollutants in the air

  • increased irritation of airways

  • coughing, wheezing, and asthma symptoms

Pre-Competition strategies to maximise performance in heat

• 7-14 days of acclimatisation in the same conditions to increase the body’s tolerance to heat

• using cooling aids such as ice vests to reduce core body temperature and delay the effects of dehydration

Competition strategies to maximise performance in heat

• pacing strategies to reduce feelings of exertion at low exercise intensities

• wearing suitable clothing to maximise heat loss

• rehydrating often with a hypotonic or isotonic solution

Post-competition strategies to maximise performance in heat

• using cooling aids such as cold fans

• rehydrating with an isotonic solution to replace lost fluids, glucose, and electrolytes