Weight-training-induced attenuation of the circulatory response of older males to weight lifting.

We examined the effects of 12 wk of dynamic strength training on the heart rate (HR) and blood pressure of older male subjects during 10 repetitions of single-arm curl and single- and double-leg press at 60 and 80% of both the pre- and posttraining maximum capacities and during single maximum lifts (1 RM). The circulatory responses were greater at 80% of 1 RM than at 60% and increased with active muscle mass. After training, the 1 RMs increased by 24 (legs) to 54% (arms) and there was a marked attenuation of HR and arterial pressure during exercise when subjects lifted the same absolute load. Greatest reductions in HR (108 +/- 4 to 94 +/- 2 beats/min), systolic blood pressure (BPs, 247 +/- 14 to 206 +/- 9 Torr), diastolic pressure (156 +/- 9 to 116 +/- 5 Torr), mean arterial pressure (143 +/- 6 to 131 +/- 5 Torr), and rate-pressure product (268 +/- 22 to 196 +/- 12 HR.BPs/100) occurred during double-leg press at 80% of the pretraining 1 RM. After training, during lifting at 60, 80, and 100% of the posttraining 1 RMs, the HRs and arterial pressures were the same as those during pretraining testing when the same relative, but lighter, absolute loads were used. These observations are consistent with a significant part of the circulatory response to weight lifting being mediated by a feedforward "central command" mechanism coupled to the relative intensity rather than to the absolute level of force.