Training prescription for anaerobic adaptations

Question 1

What are the main contributors to atp production for 1 six second sprint?

Answer 1

• PCr contributes most to a 6s sprint
• Glycolysis also has a large contribution suggesting rapid activation of glycogen phosphorylase
• Sprint 6s challenges PCr stores and glycolytic system to produce atp

Question 2

In the last sprint why has the contribution of glycolysis to anaerobic ATP production reduced?

Answer 2

• Reduction in glycogen phosphorylase activity – impaired glycogen breakdown and decreases glycogenolytic rate by 90% and 87% reduction glycolytic
• Reduction in PFK activity which causes a reduction in glycolysis
• Increase in PCR contribution to atp production

Question 3

Why should sprinters avoid training 100m sprints using rest shorter than 5 mins for pcr?

Answer 3

• Within 10s pcr content will drop by 50-75%
• To reach 100% sprint capacity, this will take longer than 5 minutes to fully re-synthesise
• Complete recovery of PCr could take up to 13mins or more

Question 4

Why does power output decline over repeated 30s maximal sprints?

Answer 4

• glycogen breakdown is minimal by the third 30s sprint suggesting muscle glycogen decreases with duration
• a reduction in glycogen breakdown makes it harder to produce ATP and therefore this is why we see a reduction in power output over the repeated bouts as glycogenolysis has reduced.
• Also have a reduction or near depletion of PCR by third 30s sprint

Question 5

When changes in metabolites are observed, explain why glycogen breakdown is low at the end of a third 30s sprint when AMP accumulation has increased largely?

Answer 5

• Glycogen phosphorylase activity is impaired by the 3rd 30s sprint therefore glycolytic rate in reduced
• Glycogen phosphorylase is inhibited by glucose 6 phosphate. The accumulation of this inhibits glycogen breakdown causing the glucose concentration gradient to become shallower.
• This results in less glucose going into the muscle fiber and therefore glucose concentration increases as it can’t enter the muscle fiber or liver

Question 6

Explain the contribution to ATP production during a 30s sprint and third 30s sprint / why

Answer 6

• Increased contribution of oxidative phosphorylation at the end of a 30s sprint (40% contribution) and it is the main contributor during the third 30s sprint for atp production (60% contribution)
• This is because there is a reduction in glycogen phosphorylase activity due to glucose 6 phosphate, reduced atp turnover, can’t meet ATP demands, reduction in muscle contraction and power output. Therefore, there is reduced reliance on PCR and anaerobic glycolysis

Question 7

What chronic adaptations would you expect to see from repeated sprint interval training?

Answer 7

• More mitochondria
• Glycogen phosphorylase and lactate dehydrogenase activity will be unchanged
• Peak power and total power output will increase and a better ability to sustain power over repeated sprints
• Hexokinase activity will increase and pfk enzyme activity will increase up regulating glycolysis – also may stop the increase in glucose 6 phosphate as hexokinase activates its

Question 8

Dose sprint interval training affect vo2max and oxidative metabolism?

Answer 8

• The more sprint intervals the higher the contribution of oxidative phosphorylation ( around 60% after third 30s sprint)
• Maximal cardiac output is the main limiter of vo2max and sprint intervals increase stroke volume and therefore cardiac output. Increase in maxQ = increases in vo2max
• Therefore, there should be increase in mitochondria and oxidative enzymes. Research shows increases of around 7% in vo2max in 6/7 weeks of repeated sprint intervals

Question 9

Explain the potential mechanism why sprint training increases oxidative enzyme activity?

Answer 9

• Sprint intervals increase the contribution of oxidative phosphorylation to atp production.
• The more intervals accompanied with shorter rest periods stresses the mitochondria
• Therefore, we see an increased aerobic contribution and increased activity of oxidative enzymes as anaerobic glycolysis and PCr cannot produce atp to the same extent
• Increases in citrate synthase, malate dehydrogenase and succinate dehydrogenase with sprint interval training.