Energy Systems
3 Systems
3 groups of energy nutrients
Muscle fibre types
Three Energy Systems
• ATP – PC (anaerobic alactic) – No oxygen
• Glycolysis (anaerobic lactic) – No oxygen
• Aerobic System – oxygen needed
Adenosine Triphosphate (ATP)
• ATP – It is re-synthesized in two ways:
•
•
Aerobically in the mitochondria = 36 ATP
or
Anaerobically in the cytoplasm = 1or 2ATP
1 molecule of PC gives 1 molecule of ATP
1 molecule of glucose gives 2 ATP + Lactate
The Three Energy Nutrients
• Carbohydrates – glucose and glycogen
• Proteins – amino acids
• Fats – fatty acids
ATP – PC system
•
•
•
•
Anaerobic alactic – no lactic acid is produced
Lasts 10 -15 seconds
Uses stored ATP and creatine phosphate
No by-products, just the product ATP
Glycolysis
• Anaerobic Lactic system
• Lasts 15 seconds – 3 minutes
• Uses glucose and glycogen to make ATP
• By – product is lactic acid
Aerobic System
•
•
•
•
•
Occurs in cytoplasm and mitochondria
Needs oxygen to produce all 36 ATP
Lasts as long as you are alive
Uses glucose, glycogen, fats, and proteins to make ATP
By-products are carbon dioxide and water
Muscle Fibre types
• Type I – slow twitch (aerobic)
• Type IIA – Fast twitch ( Fast twitch
oxidative or FOG)
• Type IIB – Fast twitch (anaerobic)
Type I
• Slow contractions but can go a long time
• Red (dark) in colour
• Predominantly used in aerobic activities
• High concentration of myoglobin – muscle
can store oxygen for regeneration of ATP
Type II A
• In between fast and slow twitch
• Faster, stronger contraction than Type I
but can be sustained longer than Type IIB
• Redish/white in colour
• Moderate myoglobin concentration
• Predominantly used in anaerobic activities
Type II B
• Fast twitch
• White in colour
• Fastest contraction speed of all muscle
fibres
• Low myoglobin concentrations
• Predominantly used in anaerobic alactic
activities – explosive lift or jump
Approximate Distribution of muscle
fibre types
Sport
% slow twitch
% fast twitch
Cycling
61
39
Middle –
59
distance runner
Sprinter
26
41
Untrained
person
58
42
74