Exercise blood flow changes in the human forearm during physical training

¹ Research Laboratories, University of California, Santa Barbara, and Department of Physiology, University of Southern California Medical School, Los Angeles, California

Forearm blood flow measurements were made with a venous occlusion plethysmograph on six competitive swimmers and six control subjects at rest and during a prescribed rhythmic exercise throughout a 13-week training and detraining program. The swimmers' mean exercise forearm blood flow increased progressively during the training program, reaching a maximum at the peak of training toward the end of the 5th week, after which it decreased to near posttraining levels during the period of detraining. The increase in the swimmer's exercise flow between the 1st week of training (4.02 ± 0.59 ml/100 ml min) and the 5th week of training (6.40 ± 0.56 ml/100 ml min) was statistically significant; their decrease in mean exercise blood flow during the 3rd week of detraining (4.70 ± 0.24 ml/100 ml min) was also statistically significant. There was no significant change in the swimmers' resting blood flow; nor were there significant changes in either the exercise or the resting blood flows of the control group. The technique for measuring blood flow in the forearm during rhythmic exercise is explained.