Exercise physiology Flashcards
What are the three energy sources for physical activity
Carbohydrates
Proteins
Fats
What is the chemical compound stored in the muscle fibre
ATP
What does ATP stand for
Adenosine triphosphate
What is ATP
A chemical compound responsible for producing energy for movement
How does ATP produce energy
1 of 3 phosphate bonds breaks and energy is released
What is food digested into
Fats, proteins and carbohydrates
What must happen when the ATP produce runs out
Resynthesis so that energy can be provided for longer periods of time
Only a very small amount of ATP is stored within the muscles, so ATP must continually be rebuilt/resynthesised so that energy can be provided for longer periods of time
How can ATP be rebuilt
- from the breakdown of phosphate creatine or
- breakdown of macronutrients (carbohydrates, proteins and fats)
Resynthesis
Energy from the breakdown of phosphate creatine or the stored forms of carbs, fats and protein are used to re-join ADP and inorganic phosphate (Pi) to resynthesis ATP
Food fuels
Carbohydrates
Fats
Protein
Chemical fuels
- ATP,
- phosphate creatine (PC),
- glycogen and glucose,
-free fatty acids & triglycerides, - amino acids
Carbohydrates
- broken down into glucose for blood transportation
- stored as glycogen in the muscle and liver
- Carbohydrates (sugar and starches, in foods such as fruit, cereal, bread, pasta and vegetables) are the body’s preferred source of fuel, particularly during exercise
GI
Glycemic index
What is the Glycemic index (GI)
- a ranking of carbohydrates based on their immediate effect on blood glucose (blood sugars)
- measured on a scale of 1-100
High GI foods
- break down quickly during digestion- therefore have immediate effect on increasing blood sugar levels
- Best consumed during and immediately after the event
High GI. During exercise
- rapid absorption and release of energy into blood stream provides opportunity to top up glycogen stores, helping the delay of depletion of glycogen stores
High GI. immediately after exercise (within 30 minutes)
- immediately after exercise muscles are most responsive to topping up fuel supplies, therefore high GI foods need to be consumed within 30 minutes of the activity finishing
Low GI foods
- Break down slowly during digestion resulting in a slow release of glucose into the blood stream
- best consumed as part of the pre-event meal and after the event to replenish supplies
Low GI. Pre-event meal (1-4 hours prior)
- slower release of glucose into bloodstream helps keep blood glucose levels topped up prior to race
Low GI. after exercise (1-24 hours post exercise)
- assist with repletion of muscle and liver glycogen stores up the 24 hour post exercise
Carbohydrate loading
- nutritional intervention aimed at delaying the depletion of glycogen stores
- occurs when the athlete increases the amount of carbohydrates consumed prior to competition with the aim being to store extra glucose in the liver and muscles
2 main methods to load
-1 day method
-3 day method
1 day method
- consume approximately 8-10g/kg body weight of carbohydrates the day before competition (approx 700g stored in muscle and liver)
This is equivalent to eating almost 3 loaves of bread in 1 day- you may need to use supplements - tapering or reducing training load is required to spare muscle glycogen stores
3 day method
- consume approximately 7-8g/kg body weight of carbohydrates for 3 days leading up to the competition (approx. 700g stored in muscle and liver)
- players can still exercise, however there is significant tapering occurring leading up to competition so as to not deplete glycogen stores
(3 day method is not suitable for sports which require athletes to perform every week -a 3 day taper leading to a match on Saturday would require a taper starting on Wednesday which is not ideal)
Advantages of carbohydrates/carb loading
- Carb 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
Disadvantages of carbohydrates/ carb loading
Binding of water to carbohydrate molecules increases water absorption, causing an increase in weight
*during exercise, CHO stores become depleted, causing an increase in the use of fats for energy
Fats have a higher oxygen cost than CHO, therefore the body must reduce exercise intensity
Glycogen sparing
- glycogen sparing of the ability of an athlete to spare glycogen supplies by using an alternative fuel source during physical activity
Achieved by 4 different methods
Glycogen sparing 4 methods
Training effect
Caffeine consumption
Pre-event meal
During the event meal
Training effect glycogen sparing
Through an aerobic training programme, athletes are better able to break down fats for a given intensity, sparing glycogen for later in the event
Caffeine consumption glycogen sparing
By consuming caffeine before the event, it better enables the athletes to break down fats at the start of the event, sparing glycogen for later in the event
Pre-event meal glycogen sparing
By consuming a low GI meal 1-4 hours prior to the event, it increases blood glucose levels allowing for the sparing of glycogen for later in the event
During the event meal glycogen sparing
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
Fats
- Fats (In butter, margarine, cheese, oil, nuts and fatty meats) are broken down into either fatty acids (FFA), which are found in adipose tissue and the blood, or triglycerides which are stored in the muscle
- They are the body’s main source of fuel at rear and during prolonged submaximal exercise
Protein
— Protein (found in meat, fish, poultry, legumes, eggs and grains) makes a negligible contribution to energy production during exercise (5-10% in ultra endurance events)
—an essential nutrient in the diet; is needed to:
- build convective tissue and muscle cells
- act as enzymes which stored up chemical reactions
— stored in the muscles and around the body
—Used mainly for growth and repair (only used as a fuel in extreme circumstances)
What are proteins, fats and carbohydrates used to form
A chemical compound
Known as ATP
Where the breaking of phosphate bonds gives energy to make muscles work
What is happening when the body is performing physical work
Converting chemical energy (ATP) produced by chemical reactions into mechanical energy (muscular contraction)
Energy systems
Anaerobic
- ATP-CP system
- anaerobic glycolysis
Aerobic
- aerobic system
Anaerobic
Without oxygen
Aerobic
With oxygen
Rate of ATP production
How quickly ATP is resynthesised
Yield
How much ATP is resynthesised