Exercise physiology Flashcards
What percentage of a person’s everyday diet should be carbohydrates?
55- 60%
What percentage of a person’s diet should be consumed as fats?
25-30%
What percentage of a person’s diet should be consumed as protein?
10-15%
What are factors (4) that affect the amount of energy consumed?
- sex of the individual
- age of the individual
- periods of growth
- levels of physical activity
What happens when you ingest carbohydrates?
- It is first converted to blood glucose leading to a rise in insulin
- excess blood glucose is stored in muscles and liver as glycogen
What are the 2 types of carbohydrates?
- Simple sugars: small molecules that are high GI
- Complex carbs: large molecules that are low GI
What is the glycaemic index?
The ranking of carbohydrates based on their immediate effect on blood glucose levels
What are low GI food? and provide 3 examples
Carbs that slowly break down, releasing glucose gradually into the blood stream
- applies, sausages and peanuts
What are high GI food? and provide 3 examples
Carbs that quickly break down and immediately increased blood sugar levels which are best consumed during and immediately after the event.
What is rebound hypoglycaemia?
A rapid rise in blood glucose levels causing an overshoot in insulin release. This significantly reduced blood sugar levels which impairs central nervous system functioning during exercise causing a negative effect on performance.
- It can be prevented by not consuming high GI foods 30-60 minutes prior to the event
What are 2 types of fats?
- Unsaturated (good). Examples: avocado and fish
- Saturated (bad). Examples: dairy
What happens when you consume fats?
- stored as triglycerides in muscle cells
- broken down into free fatty acids
What are the 4 functions of proteins?
- growth of muscle tissue
- repair of muscle tissue
- production of red blood cells, hormones and antibodies
- contribution to ATP production when carbs and fat stores are depleted
How are proteins digested?
As amino acids which are broken down to provide energy for ATP repletion
What does it mean when a person ‘hits the wall’ or is bonking?
Liver glycogen is depleted and fats become the primary fuel source. The person’s intensity is reduced as fats are more difficult to break down.
What is glycogen sparing?
The ability of an athlete to spare glycogen supplies by using an alternative fuel source during physical activity.
What are the methods of glycogen sparing?
- aerobic training: breaks down fats better, sparing glycogen for later in the event
- caffeine consumption: better enables the breakdown of fats
- low GI pre event meal: increases blood glucose levels and allows for spared glycogen for later
- high GI food during exercise to increase stored glycogen levels
What foods must be consumed as the pre- competition meal?
- a meal that is high in low GI carbs and low in fat 1-4 hours prior to event (to increase blood glucose levels and allow for spared glycogen to be used later)
- a snack 30-60 mins prior which is low/ medium GI to prevent rebound hypoglycaemia
How much fluids should you consume before an event?
- Approximately 600-1000mL of fluids 1 hour prior to the event
- 350- 500mL just prior to competition
What foods must be consumed during the event?
- 30-60g of carbs per hour of activity
- best to consume carbs in liquid form
- high GI food to allow for the rapid release of glucose into the bloodstream
What fluids must be consumed during the event?
- 100- 200mL of water every 15 minutes of long duration events
- sports drinks with 5-8% carbs to spare glycogen for later
- consume electrolytes to replace sodium ions lost via sweat
What foods should be consumed post- competition?
- high GI foods to increase glycogen stores
- consume 1g/kg of carbs within the first 30 minutes after the event
- 7-10g/kg of carbs should be consumed over the next 24 hours after competition
What fluids should be consumed after event?
- an extra 50% of fluids lost via sweat (1.5%)
- electrolytes to replace the sodium ions lost via sweat
How is heat transferred by radiation?
Heat is transferred from a warmer body to the cooler surroundings without physical contact, via electromagnetic waves.
How is heat transferred by conduction?
Heat is transferred through direct contact with another object.
How is heat transferred by convection?
By the movement of a moving substance, usually air or water. It depends on the speed and temperature of passing fluid.
How heat is transferred by evaporation?
By the transfer of heat via the evaporation of sweat off the skin, which provides a cooling effect.
- blood is cooled by cooler skin
How is heat gained by radiation?
the sun
how is heat lost by radiation?
standing in the shade
how is heat gained by conduction?
ice bath and the hot road surface and shoes
how is heat lost by conduction?
ice vests and ice baths
how is heat gained by convection?
heater, sauna, heat chamber
how is heat lost by convection?
Air conditioner, sea breeze, misting fans
How is heat gained by evaporation?
Wiping off sweat
How is heat lost by evaporation?
The evaporation of sweat
List 5 immediate responses to exercise in the heat
- increase in vasodilation of blood vessels to the skin
- increase in core temperature
- increase in sweat production
- increase in heart rate and cardiac output
- increase in respiration
What are the long term adaptations to training in the heat?
Sweat
- increase in sweat rate as sweat gland increases in size or increase in sweat sensitivity. This causes a decrease in skin temperature and a decrease in heart rate as stroke volume increases
- sweat is more diluted
Cardiovascular
- increase in heart rate and core body temperature
Explain what double heat load is
When the body is forced to deal with 2 forms of heat:
- metabolic heat created by working muscles
- environmental heat in hot conditions
What is cardiovascular drift?
An increase in sweat rate causes blood to be more viscous and a decrease in blood plasma. This therefore causes a decrease in stroke volume, a decrease in skin blood flow and a decrease in oxygen sent to working muscles. This then results in a decrease in sweat rate.
How hydration prepares body for changes in hot conditions?
Prevent dehydration
- pre exercise: start exercise in the state of hydration, hyperhydrate 1L prior
- during exercise: 200mL every 15 minutes and drink electrolytes
- after exercise: for every 1L lost, replace with 1.5L of water
How clothing can prepare body for changes in hot conditions?
- remove excess clothing
- increase the amount of skin exposed to air and moving fluid
- lightweight/ loose clothing
- cotton
How pre-cooling helps the body prepare for changes in hot conditions?
- wear cooling vests/ jackets
- cold water immersion
- ingestion of ice
What is hyponatremia/ water intoxication?
When there is too much water in blood and low sodium levels in the body.
What is heat acclimitisation?
5-10 days of exercise training in the heat resulting in increased plasma volume, an earlier onset of sweating and increased rate of sweating.
A person can heat acclimitise by:
- using a sauna
- sweaty clothing
- heat chambers
- training in the country/ location (most effective)What
What is the most and least effective heat transfer mechanism in hot conditions?
Most effective: evaporation
Least effective: other mechanisms
What does humidity mean?
The amount of water vapour that exists in the air. It limits the body’s ability to lose heat via evaporation.
What are 5 immediate physiological changes that occur in humid conditions?
- increase in core temperature
- increase in heart rate and cardiac output
- increase in sweat
- decrease in sweat evaporation
- increased blood pressure and blood viscosity
What does dehydration cause?
- cramps
- heat exhaustion: when a person is exposed to a hot environment for an extended period of time and excess sweating and vasodilation
- heat stroke: if the temperature rises and doesn’t lower, causing a decrease in blood plasma, blood flow to skin, sweating (dry skin), heat loss and an increase in body temperature
How to cope with exercise in humid conditions?
Fluid intake strategies:
- pre exercise: hyperhydraton. 1L prior: 300-400mL just prior and 600mL 1 hour prior.
- during exercise: 200mL every 15 minutes and drink electrolytes
- post exercise: for every 1L lost, replace with 1.5L with electrolytes
Pre cooling
Acclimitisation (not as effective as heat acclimitisation)
Clothing: remove excess clothing and increase skin exposure to air
What are the immediate responses to exercise in the cold?
- Peripheral vasoconstriction: the constriction of the blood vessels just below the skin surface to move blood away from the skin to prevent heat loss
- Shivering: uncontrolled muscle contractions, which causes an increase in body temperature and a decrease in fine motor skills
- Piloerection: when the hairs on the body stand up, trapping a warm layer of air on the skin and keeps the skin surface warm.
What are strategies to cope with exercise in the heat?
- Clothing: increase in clothing layers to trap heat or wear wetsuits
- Insulation by fats: rub animal fat on the skin to minimise heat loss from the body
- Increase in subcutaneous stores
- Cold acclimitisation: allows a chance for experimentation clothing/ warm up, psychological advantage, athletes are able to generate more heat and better prevent heat loss
What is hypothermia?
When there is a decrease in temperature but does not return to normal.
What do you do when someone is suffering from hypothermia?
- remove wet clothing
- keep patients aware
- wrap blankets and aluminium foil
- gradual heat application
What do you not do when someone is suffering from hypothermia?
- put in hot bath
- apply direct heat
- provide alcohol
What are symptoms that a person undergoes hypothermia
- loss of concentration
- loss of fine motor skills
- confusion
- death
- coma
- face turns blue
