PubMed1980
We have studied, in eight healthy subjects, aged 22-26 years, some cardiovascular and respiratory effects, during maximal and half-maximal isometric effort, four minutes lasting, performed with hand (handgrip). During contraction and 15 minutes lasting recovery, heart rate, arterial systolic pressure at resting arm and at limb, pulmonary ventilation, VO2 and VCO2 have been evaluated. The data of the two tests have been submitted to the Student's test. During isometric contraction and recovery, heart rate rapidly increases and decreases, respectively, without significant differences between the two contractions. The abrupt increase of the systolic arterial pressure is greater during maximal work, at resting arm; arterial pressure at limb increases rapidly during contraction, but do not varies between the two efforts. These arterial pressure responses to isometric contraction presumably are related to a neurogenic vasoconstriction. During recovery of maximal work, the systolic arterial pressure, at limb, is significantly greater than basal values from 5th to 15th minute and versus the half maximal effort at 7th, 10th and 15th minute, presumably because the vasoconstriction is still effective. Pulmonary ventilation, VO2 and VCO2 increase during contraction; VO2 and VCO2 further increase after 10 minutes of recovery, probably because the debt of O2 is repaid.