energy definition
capability or ability to produce work
amount of kj in 1g of fat, carbohydrates and protein
fat –> 37 kj
carbohydrate –> 26 kj
protein –> 17 kj
how is energy converted in the body?
chemical energy released in the breakdown of food –> resynthesis of ATP –> breakdown of ATP –> muscle contraction
what must happen for a muscle to contract?
energy released from the breakdown of ATP
what is atp?
adenosine triphosphate
purpose of energy systems
provide energy required by muscles for movement
why is resynthesis of ATP important?
enables the body to keep using ATP for muscular contractions
the energy system used is dependent on two factors…
duration and intensity
energy systems are used not in isolation but…
simultaneously. however, at particular times within a sport, a particular system will be dominant.
flow of energy
chemical energy –> mechanical energy –> movement
energy from the breakdown of food is used in…
the resynthesis of ATP
energy released from the break down of ATP causes…
muscle contractions
alactacid system (ATP/PC)
INTENSITY:
- High → (95-100% maximal effort)
source of fuel
SOURCE OF FUEL:
- ATP and phosphocreatine/creatine phosphate (CP) are available within muscle cells (myocytes).
- As ATP is broken down into ADP and P, the ADP reacts with PC (w/o oxygen) in myocyte to produce ATP and C
efficiency of ATP production
(draw diagram of ATP breakdown)
EFFICIENCY OF ATP PRODUCTION:
- Very fast rate of ATP production for a very limited time
- Limited storage of fuel
- (1 ATP per PC)
DURATION:
- 10-12 sec
CAUSE OF FATIGUE:
- Depletion of CP stores in muscle
BY PRODUCTS:
- Heat
PROCESS & RATE OF RECOVERY:
- 50% CP restored after 30 secs
- 100% CP restored after 2 minutes
EXAMPLES OF SPORT:
- 100 m sprints
- Shot put
lactic acid system
INTENSITY:
- Moderately high → (85-95% maximal effort)
source of fuel
SOURCE OF FUEL:
- Glycogen stored in muscle and liver. Glucose in blood
- Glycogen stores replenished through carbohydrates (CHO)
- Anaerobic glycolysis (glucose → ATP)
EFFICIENCY OF ATP PRODUCTION:
- Fast rate of ATP production
- Quick onset of fatigue due to build-up of lactic acid
- (2 ATP per glucose molecule)
DURATION:
- 30 sec (>90%)
- 2 minutes (85-90%)
CAUSE OF FATIGUE:
- Continued high intensity means lactate cannot be removed fast enough, resulting in a build-up of pyruvic acid.
- The build-up of hydrogen ions within the muscle causes fatigue. It increases the acidity of the muscle, causing the enzymes needed for anaerobic glycolysis to slow down.
BYPRODUCTS:
- Lactic acid (pyruvic acid)
PROCESS & RATE OF RECOVERY:
- 30 min - 2hr (active recovery)
- Lactic acid is broken down in the liver in the presence of oxygen - some is converted back into glycogen
EXAMPLES OF SPORTS:
- 400m & 800m run
- 50m & 100m swim
(draw diagram of anaerobic glycolysis system)
aerobic system
INTENSITY:
- Moderately high → (85-95% maximal effort)
source of fuel
SOURCE OF FUEL:
- Glycogen stored in muscle and liver. Glucose in blood
- Glycogen stores replenished through carbohydrates (CHO)
- Anaerobic glycolysis (glucose → ATP)
EFFICIENCY OF ATP PRODUCTION:
- Fast rate of ATP production
- Quick onset of fatigue due to build-up of lactic acid
- (2 ATP per glucose molecule)
DURATION:
- 30 sec (>90%)
- 2 minutes (85-90%)
CAUSE OF FATIGUE:
- Continued high intensity means lactate cannot be removed fast enough, resulting in a build-up of pyruvic acid.
- The build-up of hydrogen ions within the muscle causes fatigue. It increases the acidity of the muscle, causing the enzymes needed for anaerobic glycolysis to slow down.
BYPRODUCTS:
- Lactic acid (pyruvic acid)
PROCESS & RATE OF RECOVERY:
- 30 min - 2hr (active recovery)
- Lactic acid is broken down in the liver in the presence of oxygen - some is converted back into glycogen
EXAMPLES OF SPORTS:
- 400m & 800m run
- 50m & 100m swim
(aerobic glycolysis, krebs cycle and electron transport system)
oxygen role in alactacid system
RECOVERY:
Oxygen helps restore depleted PC levels in muscle during the recovery period where the body returns to aerobic metabolism.
oxygen role in lactic acid system
RECOVERY:
Oxygen is used to convert lactic acid into pyruvate then glucose, which can be used for energy in the aerobic system or converted into glucose in the liver.
It reduces the concentration of lactic acid in blood and muscle, thus preventing prolonged muscle fatigue → “Excess post-exercise oxygen consumption (EPOC)
oxygen role in aerobic system
DURING EXERCISE:
Oxygen is used to break down carbohydrates, fats and proteins to produce ATP through aerobic glycolysis, Kreb’s cycle and electron transport chain
RECOVERY:
After prolonged exercise, oxygen is used to produce ATP, repair muscles and replenish energy stores. This period is also where breathing and heart rate remain elevated to support recovery (EPOC)
types of training and methods
aerobic e.g. continuous, fartlek, interval, circuit
anaerobic e.g anaerobic interval
flexibility e.g. static, ballistic, PNF, dynamic
strength training e.g. free/fixed weights, elastic, hydraulic
when placed under stress from a training load…
the body undergoes specific physiological adaptations
