Physiology of Exercise - The anaerobic threshold concept - Altered physiological responses to exercise above the anaerobic threshold

7 important questions on Physiology of Exercise - The anaerobic threshold concept - Altered physiological responses to exercise above the anaerobic threshold

Why are glycogen reserves depleted faster during exercise above AT?

For every glycosyl molecule, 3 ATP's can be formed anaerobically (in contrast: 37 ATP aerobically). Thus the rate of glycogen utilization is increased.

Why is the exercise endurance impaired when exercising anaerobically?

Probably because ATP can not be regenerated at an adequate pace.

What effect has exercising above AT on oxyhemoglobin dissociation?

The increase of H+ facilitates the dissociation of O2 from hemoglobin. In this way the critical capillary pO2 can be maintained, so ATP regeneration can continue.
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Besides the increase of [H+] there is also an other mechanisms responsible for the dissociation of O2 from hemoglobin, especially below LAT. Name that mechanism.

The pO2. When pO2 decreases more O2 is dissociated from hemoglobine to maintain O2 supply for the mitochondria

What mechanism is responsible for the increase of [Na+] and [Cl-] in the arterial blood when exercising above LT?

Because lactate and other byproducts accumulate in the muscle the ratio between water and other molecules is altered. To compensate for this, extracellular water shifts from the extracellular to the intracellular space in the muscle. So less volume remains in the extracellular space and increased cation and anion concentrations are the result

Does VO2 reach a steady state when performing above AT? And VCO2?

VO2 does not reach a steady state when performing above AT. Below AT it will reach a steady state after 3 minutes. VCO2 does reach a steady state exercising below AT as well as above AT. Fig 2.38

When performing above AT which 2 mechanisms contribute to the increase of VCO2?

1. The additional CO2 from H+ buffering
2. The reduction of [HCO3 -] in the plasma --> this makes the blood more acidic so the carotic bodies sense extra H+ which increases the ventilatory drive.

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