Exercise physiology Flashcards
food we eat
our body makers ATP from the nutrients we eat
what are carbohydrates converted to, stored as and stored in
glucose
glycogen
muscle and liver
what are fats converted to, stored as and stored in
fatty acids
triglycerides
adipose tissue
what are proteins converted to, stored as and stored in
amino acids
polypeptide chain
muscle
role of macronutrients
carbohydrates: preferred fuel source
fats: readily used at rest or once carbs are used
protein: extreme conditions, ultramarathons, etc
ATP breakdown
energy for muscle contraction is released when the 3rd phosphate is broken (leaving ADP, phosphate and energy)
Energy pathways and systems
Anaerobic pathways (no O2)
- ATP-CP system
- Lactic acid system
Aerobic pathway (with O2)
- Aerobic system
predominant energy system is dependent on the intensity and duration of the physical activity
balanced diet requirements
- adequate water intake
- limit foods high in saturated fats (cakes, biscuits, fried foods)
- limit intake of high sugar foods (soft drinks, lollies)
- limit intake of high salt foods
- limit alcohol intake
Carbohydrates
- about 55% of typical diet
simple carbohydrates - small molecule which is easily broken down, eg. sugar, honey, fruit juice
complex carbohydrates - large molecule mainly found in plant-based foods, e.g. potato, bread, cereals, rice and pasta - converted to blood glucose leading to a rise in insulin levels
- excess blood glucose converted to glycogen
speed of glucose release varies depending on the type of carbohydrate eaten (GI)
recommended dietry intake of CHO
non-athletes
- 45 - 55% of total daily caloric intake
- approx. 4.2g/kg
athletes
- 60% total daily caloric intake
- approx. 7-8g/kg daily
heavy training
- 70% total daily caloric intake
- approx. 8-10g/kg daily
Glycaemic Index (GI)
- ranking of carbohydrates base on their immediate effect on blood glucose (blood sugar) levels
- measured on a scale of 1 (low) - 100 (very high)
Low GI foods
- apples
- lentils
- kidney beans
- peanuts
- navy beans
- sausages
Moderate GI foods
- corn
- peas
- white pasta
- sweet potatoes
- oranges
- oatmeal
High GI foods
- pure glucose - GI of 100
- honey
- white bread
- white rice
- gel shot
High GI
- break down quickly during digestion - immediate effect on increasing blood sugar levels
During exercise - rapid absorption and release or energy into bloodstream provides opportunity to top up glycogen stores, helping with glycogen sparing
Immediately after (first 30 mins) - immediately after exercise muscles are most responsive to topping up fuel supplies
Low GI
- break down slowly during digestion - releasing glucose gradually into the blood stream
- best consumed as part of the pre-event mean and after the event to replenish supplies
Pre-event meal (1-4hrs prior) - slower release of glucose into bloodstream helps keep blood glucose levels topped up prior to race
After exercise (1-24hrs post exercise) - assists with repletion of muscle and liver glycogen stores in the 24hrs post exercise
Rebound hypoglycaemia
- athletes must be careful they don’t consume high GI foods 30-120min prior to event as it may cause rebound hypoglycaemia
- immediately after eating CHO, there is a rise in blood sugar levels resulting in the hormone insulin being released into the blood and lowering blood sugar levels
- when an athlete consumes high GI foods just prior to physical activity, we see a rapid rise in blood sugar levels causing an overshoot in insulin release
- this insignificant reduces blood sugar levels which impairs CNS functioning during exercise causing a negative effect on performance
Fats
- about 30% or average diet
fat consumption beyond this - leads to overweight and cardiovascular disease
saturated fats (usually from animal fats e.g. milk, cheese) - are associated with cardiovascular problems
unsaturated fats (avocado, nuts, fish) - are considered healthy fats when consumed in moderation - fat stores are not limited and provide a plentiful source of energy - especially in submaximal exercise conditions (e.g. rest, gentle walking)
Protein
- about 15% of average diet
average active people need about 0.6g/kg
endurance athletes may need up to 1.6g/kg
body builders may consume up to 30% of their overall energy intake from protein sources
mainly involves in maintaining the structure of the body and is vital in growth and repair of tissues
acclimatisation
the process of an athlete adjusting to new environmental conditions in order to assist with performance
conduction - definition
the transfer of heat through direct contact with another object
convection - definition
the transfer of heat through the movement of air or water
evaporation - definition
transfer of heat resulting from evaporation of sweat from the body
glycaemic index
the degree to which carbohydrates can affect bloody glucose levels
hydration
the process of replacing water in the body
macrocycle
longest part of a training program, typically 1 year (made up of many mesocycles and microcycles)
mesocycle
a block of training that usually lasts 3-4 microcycle (weeks) and is designed to achieve a specific goal
microcycle
the shortest phase of a training program, usually 1 week
peaking
planning training in such a way that mental, physical and emotional attributes reach optimal performance at the appropriate time (usually finals)
periodisation
the process of breaking up a training program into smaller blocks, often related to the performance (season)
radiation - definition
the transfer of heat to/from surroundings. Heat moves from warmth to cool
tapering
reducing an athlete’s or team’s training load in the lead up to competition in order to optimise performance
diet comparision
inactive individual
55% carbohydrates
30% fats
15% protein
endurance athlete
70% carbohydrates
16% fats
14% protein
pre-performance
before competition, carb stores and fluid levels should be at maximum capacity - especially for endurance based events where every bit of energy is important
carbohydrate loading
- aimed at maximising the glycogen stores in the muscle prior to competition
- involves eating a high carb diet in the days leading up to an endurance event in conjunction with a reduction in training load (taper)
- by carb loading, an athlete can work at a higher intensity for longer before stores of glycogen are depleted
- only effective if event is longer than an hour
- in high intensity events, carb loading may be detrimental because glycogen storage also leads to water storage meaning increased weight
- to cab load properly, athletes may have to eat a large amount of food
- some athletes may use carb supplements or drinks to meet carb loading demands
carbohydrate loading advantages
- CHO loading avoids the depletion of glycogen stores by increasing muscle and liver glycogen levels
- by sparing glycogen, it allows aerobic athletes to maintain a higher intensity for a longer period of time
carbohydrate loading disadvantages
- binding of H2O to CHO molecules increases water absorption, causing an increase in weight
glycogen sparing
is the ability of an athlete to spare glycogen supplies by using an alternative fuel source during physical activity via:
- training effect
- caffeine consumption
- pre-event meal
- during the event meal
glycogen sparing - training effect
through an aerobic training program, athletes are better able to break down fats for a given intensity, sparing glycogen for later in the event
glycogen sparing - caffeine consumption
by consuming caffeine before the event, it better enables the athlete to break down fats at the start of the event, sparing glycogen for later in the event
glycogen sparing - pre-event meal
by consuming a low GI mean 1-4hrs prior to the event, it increases blood glucose levels allowing for the sparing of glycogen for later in the event
CHO loading before the event DOES NOT achieve this is it is used to increase initial stores of muscle and liver glycogen
glycogen sparing - during the event meal
by consuming high GI foods during the event, it allows blood glucose levels to be constantly topped up, sparing the use of glycogen as a fuel source
hydration
we lose water from the body via breathing, sweating and urinating
aerobic events
- require high amounts of CHO
- combination of high GI / low GI
- adequate protein for repair of muscle fibres damaged at training and following exercise
- maintain adequate fluid intake
anaerobic events
- power athlete needs more protein than endurance athletes
- power athletes require high amounts of CHO to provide fuel for training
- maintain adequate fluid intake
days prior to comp
CHO loading combined with exercise taper to top up glycogen supplies - Low GI (10-12g/kg)
maintain fluid intake to ensure optimal hydration
pre-comp meal
low GI meal to top up glycogen supplies
1L of fluid to assist with hyperhydration (assume warm to hot whether)
pre-comp snack
small low GI snack to top up glycogen stores (1-15g carbs)
High GI immediately before activity, otherwise hypoglycaemic rebound is triggered
maintain hydration (200-600ml/hour)
during comp
30-60g of high GI CHO per hour
200ml of fluid every 15min (500-1L/hour)
post-comp snack (first 30min)
1g/kg of body mass of high GI CHO within 30min after event
commence fluid replenishment with the goal to replace 1.5 weight loss
post comp meal (next 24hrs after)
consume 7-10g/kg body mass of low to moderate GI CHO within 4-6 hours consume protein to assist with muscle repair
consume fluid/electrolytes which equates to 1.5 weight loss
immediate effects of exercise
The circulatory system
The respiratory system
The muscular system
The skin
immediate effects of exercise - The circulatory system
- increase in heart rate (beats per minute)
- increase in stroke volume (more blood per beat)
These results in cardiac output (output of blood per minute - HR x SV = CO) - increased systolic (squeeze) blood pressure
- increase in arteriovenous oxygen difference (a-vO2 difference)
- blood flow is diverted to the working muscles due to vasodilation in the vessels leading to the muscles
results: - increased delivery of O2 / glucose to working muscles
- quicker removal of CO2 from the working muscles
immediate effects of exercise - The respiratory system
- increased breathing rate (breaths per minute)
- increased tidal volume (volume of air inhaled or exhaled with each breath)
These both increase the minute volume
result: - faster gas exchange at lungs and tissues = faster oxygenation of the blood
immediate effects of exercise - The muscular system
- increased muscle contraction = more energy required
- greater use of O2 and glucose
This means that lots more CO2 is produced (and some lactic acid) - working muscles produce heat as a by-product, the body starts to warm up and temperature rises
results:
O2 and glucose used up quickly by the cells increased CO2 produces (and some lactic acid) increased heat produced
immediate effects of exercise - The skin
- cooling effect - blood vessels beneath the skin open up (vasodilate) to allow the blood to pass close to the surface and lose heat - this causes the skin to become pink/red
- sweat is produced by the sweat glands and then evaporates taking heat energy away from the skin
result: - vasodilation of skin capillaries and evaporation of sweat causes the body to lose heat and maintain normal temperature
Olympic environmental considerations
- Beijing 2008 - pollution
- Athens 2004 - heat
- Seoul 1988 - humidity
- Mexico 1968 - altitude
Thermoregulation
- to maintain homeostasis (normal functioning) - approx. 37°C
- controlled by the hypothalamus in the brain, it receives input from thermal receptors in the skin
- the body tightly regulates temp as even small deviations (+/- 3°) can be fatal
- ambient temperature
- core temperature
- to lose heat, vessels dilate (open) to allow blood to circulate nearer skin
- to conserve heat, blood vessels vasoconstrict (close)
ambient temperature
the temperature of the environment the athlete is performing in
core temperature
the temperature inside the athletes body
heat gain
hormones
environment
muscular activity
basal metabolic rate
heat loss/transfer
radiation
conduction
convection
evaporation
conduction
transfer of heat through direct contact (from hot to cold object)
e.g. ice vest, ice pack
radiation
transfer of heat from warmer object to cooler object through electromagnetic waves (not directly touching heat source)
e.g. sun and us, snow and us
convection
transfer of heat through a moving substance (usually air or water)
- if you are still, you have a layer of air/water around you that warms up. If that air is moved (wind) then your body is continually trying to warm up the layer around it
e.g. breeze, currents
evaporation
when a liquid (sweat) becomes a gas
when sweat evaporated, heat energy is taken from the skin
most effective in dry conditions
as humidity increases, evaporation becomes less effective
rate of sweating is dependent on
- gender (male more than female)
- number of sweat glands
- body surface are (increase SA + increase sweat)
- how fit you are (increase fitness = increase sweat if all factors are equal e.g. body SA)
Excessive sweating leads to a loss of body fluids and when level of fluid drops, body’s core temp increases - this gradual dehydration leads to heat exhaustion and heatstroke
- sweat loss can reach 6-10% of body mass
- > 2% generally means performance and thermoregulation are comprised
methods of heat transfer
the body’s preferred mechanism of heat loss is dependent upon the following three factors
environment
age
physiological state
Environment - heat loss
- ambient temperature - if above the body’s core temperature, then evaporation is the only method of heat loss. Other methods will gain heat
- forced convection - heat loss via convection will occur if it is windy
- barriers to convection - clothing will minimise the effect of convection as it will insulate the boundary layer of air
- temperature radiating surfaces - light clothing will not absorb as much as dark clothing
- relative humidity - if 100%, no heat loss via evaporation
Age - heat loss
- children don’t swear is much as their sweat glands are not as developed as adults.
- Children produce more heat, but have a lower sweat capacity = prone to heat illness
Physiological state - heat loss
- rate of heat production (how much work the athlete is performing)
- hydration state - will determine rate of evaporation as a reduction in plasma volume leads to a decrease in sweat rate
Environmental factors
- heat
- humidity
- cold
- altitude
Response to exercise - heat
- increase sweat produced
- blood vessel dilation and peripheral blood flow
- skin and core temp increases
- ventilation increases
- HR, SV, CO, BP all increase
- causes body temp increase
Double heat load
where the body is forced too deal with 2 forms of heat (muscles v skin)
