Question

When measuring exercising energy expenditure via indirect calorimetry, it is important that the exercise be primarily aerobic for the most accurate results. Why is this?

Lactate can be produced during both anaerobic exercise and aerobic exercise. Explain how this is possible. What are some factors that contribute to the production and accumulation of lactate during aerobic exercise?

The rate of glycogen depletion is positively correlated with exercise intensity. Why is this?

Answer 1

There can be two types of respiration:

(a) Aerobic

(b) Anaerobic

During aerobic respiration, oxygen uptake takes place. It is documented that oxygen uptake is propotional to the metabolic heat production. The later is measured by the calorimeter. In both type of respiration first, the glycolysis process occurs which leads to production of pyruvate molecules. this pyruvate can have two fate:

1) It can be converted into the acetyl molecule which then is used for driving the krebs cycle. This is the case of aerobic respiration.

2) It can be converted into the lactate molecule during anaerobic condition.

Lactate can be produced both in the aerobic as well as anaerobic exercise as during harsh/continuous aerobic exercise the body is not able to receive sufficient amount of oxygen molecule so under this condition the lactate molecule is formed from the pyruvate molecule which can provide energy to the body.

The rate of glycogen depletion is positively related to the exercise intensity because its depletion is necessary for ATP formation which is the ultimate source of energy