Training prescription for anaerobic adaptations/ Acute and chronic responses to maximal exercise

Question 1

In the tenth and final 6 second sprint, why has the contribution of glycolysis to anaerobic ATP production reduced?

Answer 1

Glycogen utilisation decreases during sprints to prevent glycogen from fully depleting

Inhibition of Glycogen phosphorylase is linked to the reduces glycogen contribution during the last sprints

Oxidative phosphorylation increases to compensate ATP reduction in anaerobic sources.

Question 2

You investigate the effect of sprint training intervention on phosphofructokinase activity (PFK). Explain the effects of training on PFK enzyme activity, and how changes to PFK enzyme activity will affect metabolism and sprint performance.

Answer 2

PFK activity increases

Allows greater glycolytic flux and therefore ATP re-synthesis from muscle glycogen

Higher power outputs are sustained for a longer period of time.

Question 3

Between 10 and 20 s of a maximal sprint, why does the anaerobic contribution to ATP production fall by 50% yet power output only falls by 30%.

Answer 3

The decline in anaerobic ATP re-synthesis is due to reduced reliance on PCr and anaerobic glycolysis

To compensate, VO2 and Oxidative phosphorylation increases

Increased ATP re-synthesis by oxidative phosphorylation (aerobic pathways) offers a partial compensation for the decline in anaerobic ATP re-synthesis

Question 4

With reference to PCr, why should sprinters avoid training their 100 m sprint using short (< 5 min) recovery periods?

Answer 4

The 10s will drop PCr content by >50-75%

To reach 100% sprint capacity, this will take longer than 5 minutes to fully re-synthesise

Complete PCr recovery could take 13 min or more