The Effect of Phlebotomy on Physiological Responses during Submaximal, Prolonged Exercise

Area of Science:

• Exercise Physiology
• Human Physiology
• Sports Science

Background:

• The physiological effects of reduced blood volume during prolonged submaximal exercise remain incompletely understood.
• Acute phlebotomy serves as a model to investigate the impact of decreased circulating blood volume on exercise responses.

Purpose of the Study:

• To examine the influence of acute phlebotomy (reduced blood volume) on physiological responses during 60 minutes of submaximal exercise.
• To determine the subsequent effect of reduced blood volume on severe-intensity exercise performance.

Main Methods:

• A randomized, sham-controlled design was employed with 17 moderately trained participants.
• Participants underwent either phlebotomy (7% blood volume withdrawal) or a sham procedure.
• Cardiorespiratory, metabolic, perceptual, and neuromuscular responses were measured during submaximal exercise and a subsequent time-to-task failure trial.

Main Results:

• Phlebotomy significantly increased ventilation, heart rate, and blood lactate levels during submaximal exercise.
• Key parameters like oxygen uptake (V̇O2), perceived effort, and maximal voluntary contraction remained unaffected.
• Time to task failure during severe-intensity exercise was reduced by 24% following phlebotomy.

Conclusions:

• Reduced circulating blood volume significantly impacts physiological responses during submaximal exercise.
• Decreased blood volume negatively influences subsequent severe-intensity exercise performance.
• Physiological changes observed during submaximal exercise after phlebotomy were correlated with performance decrements.