Effect of 400 ml blood loss on adaptation of certain functions of the organism to exercise.

Eighteen men aged 19-23 years, volunteer blood donors, donated 400 ml of blood. Twenty-four hours before donation, one hour and 24 hours after it they performed a 10-minute exercise on Monark cycle ergometer at workloads raising the heart rate to 170/min. During the exercise the oxygen uptake (VO2), carbon dioxide elimination (VCO2), respiratory quotient (RQ), oxygen uptake to maximal oxygen uptake ratio (VO2/VO2 max), heart rate (HR) and systolic and diastolic arterial blood pressure (Ps and Pd) were determined. The obtained results were compared with the values of haemoglobin concentration and erythrocyte count. One hour after blood donation raised values of HR and Pd were obtained (p less than 0.05) with decreased Ps (p less than 0.05) and VO2 (p less than 0.05). Twenty-four hours after blood loss these parameters were not different from the initial ones (p less than 0.05). Submaximal exercise performed 1 hour after blood loss produced a significantly greater increase of the heart rate than this exercise performed before blood loss. The values of VO2, VCO2, and VO2/VO2 max were slightly lower and those of RQ and HRXPs slightly higher than during control exercise (p less than 0.05). Exercise performed 24 hours after blood loss caused identical changes in these parameters as during control tests.