Cardiovascular response to static handgrip in trained and untrained men

The influence of aerobic capacity on the cardiovascular response to handgrip exercise, in relation to the muscle mass involved in the effort, was tested in 8 trained men (T) and 17 untrained men (U). The subjects performed handgrip exercises with the right-hand (RH), left-hand (LH) and both hands simultaneously (RLH) at an intensity of 25% of maximal voluntary contraction force. Maximal aerobic capacity was 4.3 l·min−1 in T and 3.21·min−1 in U (P<0.01). The endurance time for handgrip was longer in T than in U by 29% (P<0.05) for RH, 38% (P<0.001) for LH and 24% (P<0.001) for RLH. Heart rate (fc) was significantly lower in T than in U before handgrip exercise, and showed smaller increases (P<0.01) at the point of exhaustion: 89 vs 106 beats·min−1 for RH, 93 vs 100 beats·min−1 for LH and 92 vs 108 beats·min−1 for RLH. Stroke volume (SV) at rest was greater in T than in U and decreased significantly (P<0.05) during handgrip exercise in both groups of subjects. At the point of exhaustion SV was still greater in T than in U: 75 vs 57 ml for RH, 76 vs 54 ml for LH and 76 vs 56 ml for RLH. During the last seconds of handgrip exercise, the left ventricular ejection time was longer in T than in U. Increases in cardiac output (Qc) and systolic blood pressure did not differ substantially between T and U, nor between the handgrip exercise tests. It was concluded that handgrip exercise caused similar increases inQc in both T and U but in T the increased level ofQc was an effect of greater SV and lowerfc than in U. Doubling the muscle mass did not alter the cardiovascular response to handgrip exercise in either T or U.