Question

Consider the metabolic pathways involved in generating energy/ATP to support an athlete during a 400 m race vs a marathon event. Discuss the reasons why using a specific energy pathway is preferred, or is even possible, in the context of activity intensity and duration.

Answer 1

• There are 3 systems of energy - immediate ATP-creatine phosphate, short time anaerobic glycolysis and long time aerobic glycolysis
• the immedite ATP-creatine phosphate is only a immediate source of the energy as the already stored ATP in the muscles are used in this case. The already stored ATP will deplete very fastly, it is applicable for a limited time only
• The short time anaerobic glycolysis is in which glucose from the stored carbohydrate is converted to the lactic acid with production of 2 ATP molecules. This can supply the requirement for upto a short time as the lactic acid acculmulation reduce the activity of the muscle nd also the amount of ATP produced is low
• The long time aerobic glycolysis is the long time supply of the energy as in each process 4 ATP is generated and occurs in the presence of oxygen so that pyruvate is produced instead of lactic acid so that the pyruvic acid enter TCA cycle so the further production of ATP occurs

In 400m race

• the duration of the event will be a maximum of 2 minute so that an energy source should be of short time and provide maximum effort
• the energy system which get activated within 10 - 30 seconds with response to maximum effort is the short time anaerobic glycolysis
• And thus the specific pathway during 400m race is anaerobic glycolysis
• This pathway get activated during high intensity work as with the increase in the intensity the oxygen availability is less so that anaerobic condition occurs
• duration for upto 3 minute - they supply immediate requirement for the ATP upto 3 min by depleting the carbohydrate by activated within 10 - 30 seconds of the action

In marathon

• The duration of the marathon will be 4 to 5 hours that is it requires continous source of the energy for long duration
• This energy for the long duration is supplied by the aerobic glycolysis, the ATP production will be 4 ATP and as the product is pyruvate, it will enter TCA cycle and reaction occurs so as a total of about 36 - 38 molecules of ATP is produced . So it serve as the continuous supply of the energy for long duration
• Also the aerobic glycolysis can utilize energy from carbohydrate, fat, protein. But the main source is fat, thus utilisation of the glycogen in the body and blood glucose.So the glucose supply is also continuous
• As the marathon is a low intensity activity, the supply of the oxygen to the muscle is not interpeted so that there will be continuous supply of the oxygen and hence ensure the aerobic glycolysis
• So the specific pathway during marathon is aerobic glycolysis