Training Adaptations - Endurance Training Flashcards
4 man adaptations to endurance training
- Rates of aerobic and anaerobic energy provision
- Tighter metabolic control
- Fatigue resistance - battling against homeostasis and hydrogen ion buffering
- Economy of motion
Fibre type distribution across sports
- Greater % of slow twitch fibres in endurance based sports
- The sport doesn’t effect fibre type changes, athletes with greater ST fibres choose endurance sports
Increasing rate of aerobic energy provision - Hoppler et al (1973)
- Increase in oxidative capacity of skeletal muscles due to increase mitochondrial number, size and content
- More mitozhondira = better capacity to use oxygen
- In trained vs untrained athletes - positive correlation between number of mitochondria and increased Vo2max
Explain about tighter metabolic control - ADP stimulation of mitochondrial respiration
- ATP turnover at exercise onset produced ADP
- ADP stimulates Electron Transport Chain and the ability to use oxygen to utilise glucose and fatty acids
- Increase in mitochondria = tighter metabolic control (lower change in ADP requires to achieve the same level of oxygen consumption per gram of muscle
Hood et al (1991)
- Subjects with high mitochondria content vs low mitochondrial content
- High mitochondrial needs change in ADP of 25nmol/g
- Low mitochondrial needs change in ADP of 50nmol/g
- Less mitochondrial needs higher change in ADP to switch on the respiratory chain to consume the same amount of oxygen
Phillips et al (1986)
- Endurance exercise training for 31 days - 60% Vo2max
- After training - lower ADP accumulation when working at the same absolute work rate as pre-training
Tighter metabolic control - Karlson and Saltin, (1970)
- Increase in ADP stimulates CK and glycolysis - both associated with H+ accumulation
Untrained:
- Less mitochondrial content needs greater change in ADP
- Greater reduction in PCr and greater accumulation of lactate
- Decreased PCr and increased lactate results in earlier fatigue
Phillips et al (1986) - PCr and lactate
After training of 2h of exercise at 59% Vo2peak 5-6 times a week: - Greater PCr (less degradation) - Less Pi accumulation - Less lactate accumulation - Less reduction in muscle pH Resulting in exercise lasting for longer
Bergstrom et al (1967)- muscle glycogen availability
- Exercise at 70%Vo2max until exhaustion
- Reducing pre-exercise muscle glycogen results in decreased TTE
Shannon et al (2016) - muscle glycogen and training
- 24 weeks of HIIT training - 50% increase in muscle glycogen content
Why is muscle glycogen an efficient fuel source?
- Readily available in the cell and located next to the mitochondria
- Glucose-6-phosphate from outside the cell results in 1 more hydrogen ion accumulated, than from glucose inside the cell
- Therefore we reply on intramuscular glycogen to prolonged exercise
Increased fat oxidation - Van Loon (2004)
- Higher rates of fat oxidation in training athletes
- Training improvs the reliance on intramuscular fats
- Endurance trained athletes have 2-3 fold higher intramuscular triglycerides
High intensity interval training in elite athletes - Weston et al (1997)
- 6 sessions over 28 days (during normal training)
- 6-8 reps of 5 min at 80% PPO with 1 min recovery
- Distance covered during HIIT was reduced compared to normal training - work was the same
Results
- Increased peak power
- Reduced 40km TT
- No change in oxidative enzyme activity but significant increase in muscle buffering capacity
- Positive correlation between reduced TT and increased muscle buffering
Improved performance efficiency of continued repeated exercise (Coyle, 2005)
Lance Armstrong:
- Body mass = no change over 10 years
- Vo2max didn’t change
- No change in HR or LT
Mechanical efficiency improves over time:
- Power at given workload improves
- Muscles become more efficient to cycling
