HEMODYNAMIC-EFFECTS OF AEROBIC VS RESISTANCE EXERCISE

Previous studies suggest that aerobic exercise lowers blood pressure ( BP), while isometric exercise increases BP, at least transiently. The purpose of this study was to examine the hemodynamic effect of a 6-wee k training period of aerobic exercise or weight training. Twenty decon ditioned healthy males ages 18-36, self-selected a training regimen. T he aerobic group exercised 30 min/day, 4 times each week to achieve 60 -80% maximal heart rate. The resistance group lifted weights at 65-80% maximal voluntary contraction; 3-4 sets of 8-12 repetitions; 3 day/we ek using large muscle groups. Hemodynamic measurements of heart rate, BP, venous capacitance, forearm blood flow, and vascular resistance we re made at baseline and week 6 by plethysmography and analyzed by P-wa y ANOVA. The groups showed no differences in baseline characteristics. A training effect was confirmed by a decrease in resting heart rate i n the aerobic group (71.5 +/- 4.4 to 64.5 +/- 3.7, beats per minute, P = 0.004), and an increase in total work capacity in the weight liftin g group (6231 vs 7508, P = 0.01). Forearm blood flow increased similar ly in both groups, averaging 17% (3.5 +/- 0.2 vs 4.2 +/- 0.2 ml 100 g/ min, P = 0.03), while forearm vascular resistance fell 19% (28.8 +/- 1 .7 vs 24.3 +/- 1.7 mm Hg/ml/min 100 g, P = 0.08). The main differences between the groups after training was found in their response to isom etric stress (1/3 maximal handgrip). The weight-lifting group had a gr eater increase of forearm blood flow and venous capacitance, less incr ease in systolic BP (SEP) and a greater fall of forearm vascular resis tance, (P < 0.05) while the aerobic group had less increase in SEP and heart rate (P < 0.04) but no significant change of forearm hemodynami cs. We conclude that both aerobic and repetitive weight programs have short term favorable effects on resting forearm BP and resistance. The exercise programs differ in altering the individual's physiologic res ponse to subsequent isometric stress. However, exercise training of lo nger duration or greater intensity or frequency could alter these resu lts.