Energy Systems And Muscle Fibres Flashcards
Name 3 muscle fibre types
Type 1 (slow oxidative) Type 2a (fast oxidative glycolytic) Type 2b (fast oxidative)
Characteristics of type 1
Contraction Speed: slow Fatigue Resistance: very high Mitochondrial density: high Myoglobin content: high Capillary density: high Aerobic capacity: high Anaerobic capacity: low Force produced: low
Characteristics of type 2a muscle fibres
Contraction Speed: fast Fatigue Resistance: medium Mitochondrial density: medium Myoglobin content: medium Capillary density: medium Aerobic capacity: medium Anaerobic capacity: medium Force produced: high
Characteristics of type 2b muscle fibres
Contraction Speed: very fast Fatigue Resistance: low Mitochondrial density: low Myoglobin content: low Capillary density: low Aerobic capacity: low Anaerobic capacity: high Force produced: very high
Effect of training on muscle fibres
Increases size and strength of all fibres (known as hypertrophy)
Characteristics can be altered through training (not permanent)
E.g depending on training type 2a fibres Can take on characteristics of either type 1 or 2b muscle fibres.
Uses of energy in the body
Muscle contractions/movements Circulation of blood Transmission of nervous impulses Digestion of food Repairing and replacing muscle tissue
ATP
Adenosine triphosphate
Amount of ATP in muscle cells is exhausted in a few seconds and must be constantly re synthesised to provide continuous supply.
To release energy we must break the bonds attaching the molecules
Broken by ATPase
ATP-PC System
Phosphocreatine stored in muscles is broken down to provide energy to resynthesise ATP
Lasts 8-10 seconds
1) ATP broken down by ATPase into ADP and P and energy
2) PC broken down by creatine kinase into P and C and energy
3) ADP and P and energy makes ATP
Pros and cons of ATP-PC energy system
✅no O2 needed
✅rapid energy release
✅no waste products
✅creatine stored in muscle
❌PC stores limited (10secs)
❌takes up to 3 mins to fully replenish
The Lactic Acid System (Glycolytic System)
When ATP and PC run out and need quick energy
Intense activities 1-3mins
Relies on breakdown of glucose stored in muscle as glycogen
Without O2 it is called anaerobic glycolysis
Glucose- glucose 6 phosphate- pyruvic acid-(without o2) lactic acid and energy released to make 2 ATP
Pros and cons of lactic acid system
✅rapid (no o2 required)
✅greater energy yield than ATP PC System
❌only carbs can be used as fuel source not fats
❌glycogen stores in muscle is limited
❌lactic acid is by-product = fatigue
Aerobic energy system
Low intensity long duration work (3mins+)
Required o2 to break down glucose/fat to produce energy for aerobic glycolysis
CO2 and h2o are by-products
1) (sacroplasm in muscle cell) glucose- glucose 6 phosphate - pyruvic acid -(with o2) energy (2ATP) and Acetyl Co A
2)Krebs Cycle (in matrix of mitochondria)
Acetyl Co A - citric acid - Krebs cycle
Krebs cycle= 2ATP + CO2 + Hydrogen ions(H+) and e- —> electron transport system
3)(Electron Transport System) Hydrogen atoms split to H+ and e-
H+ is oxidised =H2O
e- provide energy to resynthesise ATP
Produces 34 ATP
Pros and cons of Aerobic System
✅18/19 more times efficient than anaerobic systems
✅CO2 and H2O by-products easily expelled from body - no fatigue
✅choice of fuel fat or carb
❌required large amounts of O2
❌complex chain reactions take longer
❌reactions depend of availability of O2
What does the predominant energy system depend on
1) intensity - more intense=greater amount of PC and muscle glycogen used. Low to medium uses aerobic system
2) Duration - high intensity and 2 mins + muscles become depleted and need repaying. Intensity will drop as aerobic system becomes more dominant
3) Fitness level
Why is predominant energy system dependant on fitness level
Higher aerobic fitness means takes longer to reach aerobic threshold where there is limited energy supply. If continued you run out of anaerobic you return to aerobic and performance drops.
High anaerobic fitness mean they can work in anaerobic zone for longer and they can tolerate higher levels of lactate in muscles. Higher point of OBLA threshold.
