The effects of isometric exercise training on resting blood pressure and orthostatic tolerance in humans

Abstract

Isometric exercise training has been shown to reduce resting blood pressure, but the effect that this might have on orthostatic tolerance is poorly understood. Changes in orthostatic tolerance may also be dependent on whether the upper or lower limbs of the body are trained using isometric exercise. Twenty-seven subjects were allocated to either a training or control group. A training group first undertook 5 weeks of isometric exercise training of the legs, and after an 8 week intervening period, a second training group containing six subjects from the initial training group, undertook 5 weeks of isometric arm-training. The control group were asked to continue their normal daily activities throughout the 18 weeks of the study. In all subjects orthostatic tolerance, assessed using lower body negative pressure (LBNP), and resting blood pressure were measured before and after each of the 5 week training or control periods. Estimated lean leg volume was determined before and after leg-training. During all LBNP tests, heart rate and blood pressure were recorded each minute, and the time taken to reach the highest heart rate was derived (time to peak HR). Resting systolic blood pressure (mean & s.D.), when measured during the last week of trainiig was significantly reduced after both leg (-10 f 8.7 mmHg) and arm (-12.4 5 9.3 mmHg P < 0.05) isometric exercise training, compared to controls. This reduction disappeared when blood pressure was measured immediately before the LBNP tests, which followed training. Orthostatic tolerance only increased after leg-training (20.8 f 16.4 LTI; P < 0.05) and was accompanied by an increased time to peak HR (119.8 4 106.3 beats mir-'; P < 0.05) in this group. Blood pressure responses to LBNP did not change after arm-training, leg-training or in controls (P > 0.05). There was a small but signiticant increase in estimated lean leg volume after leg-training (0.1 f 0.1 1; P < 0.05). These results suggest that lower resting blood pressure is probably not responsible for the increased orthostatic tolerance after isometric exercise training ofthe legs. Rather, it is possible that the training altered some other aspect of cardiovascular control during orthostatic stress that was apparent in the changes in heart rate. Legtraining was accompanied by increases in estimated lean leg volume. The effects of isometric training on orthostatic tolerance appear to be specific to limbs that are directly involved in LBNP testing. Expen 'menfal Physiology (2002) 87.4, 507-5 15.

The effects of performing isometric training at two exercise intensities in healthy young males

“…It is well established that isometric exercise training (IET) causes a reduction in resting blood pressure (BP) (Wiley et al 1992;Ray and Carrasco 2000;Howden et al 2002;Taylor et al 2003;McGowan et al 2004McGowan et al , 2006bMcGowan et al , 2007Visocchi et al 2004;Millar et al 2008). However, there has not been any systematic exploration of the extent to which the intensity of this training influences these reductions.…”

Effect of Isometric Strength Training on Blood Pressure: Systematic Review of Literature with Specific Emphasis on Indians

“…There was no association between duration of intervention and BP reduction. Hand grip exercise seems to be superior to that of leg press exercise in hypertensive subjects (Howden et al, 2002). 3 sessions per week is superior to that of 5 sessions per week (Badrov et al, 2013a) and followed by most of the studies.…”

Impact of Resistance Training on Blood Pressure: Are All Contractions Created Equal?

“…3,4 In particular, 1 randomized, controlled study, not included in the meta-analysis, yet published before the database cutoff, 1 supports similar BP effects. 4 In this study, the effects of leg isometric RT intensity on resting BP were also examined, documenting no significant differences between training completed at Ϸ10% and Ϸ21% of maximal voluntary contraction (although modest reductions in BP were observed in young normotensives versus controls).…”

“…4 These data would lend significant additional support to the potential role of isometric RT in reducing resting BP, because the results will have been confirmed independently when using both isometric handgrip and leg training modalities. [2][3][4] Acknowledging the limitations associated with drawing conclusions from small-scale and nonblinded intervention trials, the isometric RT-induced reductions in resting BP appear similar in magnitude to many pharmacotherapies, demonstrating the potential clinical use of this relatively unexplored exercise training mode. Importantly, these reductions have been consistently demonstrated across both normotensive and medicated hypertensive cohorts.…”