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

Abstract

No previous studies have examined the effects of isometric training intensity upon resting blood pressure (BP). The aims of this study were (a) to compare the effects of leg isometric training, performed at two intensities, upon resting systolic-SBP, diastolic-DBP and mean arterial-MAP BP; and (b) to examine selected cardiovascular variables, in an attempt to explain any changes in resting BP following training. Thirty-three participants were randomly allocated to either control, high- (HI) or low-intensity (LI) training for 8 weeks. Participants performed 4 x 2 min exercise bouts 3x weekly. Resting BP was measured at baseline, 4-weeks and post-training. SBP, DBP and MAP fell significantly in both groups after training. Changes were -5.2 +/- 4.0, -2.6 +/- 2.9 and -2.5 +/- 2.2 mmHg [HI]; -3.7 +/- 3.7, -2.5 +/- 4.8 and -2.6 +/- 2.5 mmHg [LI] for SBP, DBP and MAP, respectively. There were no significant changes in BP at 4 weeks. No significant changes were observed in any of the other cardiovascular variables examined. These findings suggest that isometric training causes reductions in SBP, DBP and MAP at a range of exercise intensities, when it is performed over 8 weeks. Furthermore, it is possible to reduce resting BP using a much lower isometric exercise intensity than has previously been shown.

Home-based isometric exercise training induced reductions resting blood pressure

“…The resting BP reductions are similar in magnitude to those previously reported following IET that was partly laboratory-based with participants performing constant force contractions (McGowan et al 2007a;Millar et al 2013a) and completely laboratory-based using constant EMG contractions (Devereux et al 2010;Wiles et al 2010;Gill et al 2015). Furthermore, the rate of reduction in all resting BP parameters occurred at either a faster or equal rate (Devereux et al 2010) to that reported previously in normotensive participants following bilateral-leg IET using the same acute programme variables and exercise intensity in a laboratory setting.…”

“…A growing body of research demonstrates that isometric exercise training (IET), albeit conducted predominantly in a laboratory setting, is capable of lowering resting blood pressure (BP) (Devereux et al 2010;Wiles et al 2010; Baross et al 2012;Badrov et al 2013;Millar et al 2013a) equally in both males and females (Badrov et al 2016). Furthermore, the results of meta-analysis and evidence based review suggest that IET may be the most effective type of exercise to achieve clinically meaningful reductions in this important cardiovascular risk factor (Millar et al 2013a;Carlson et al 2014).…”

“…Some studies have utilised an alternative style in which IET was completed at a participant-specific EMG activity value that equated to a percentage of their peak heart rate (Devereux et al 2010;Wiles et al 2010;Baross et al 2012). However, these protocols required the use of an isokinetic dynamometer and electromyography, which are not only expensive but also require an individual to continually travel to and from a facility to complete their training using the specialist equipment under supervision.…”

“…As Q does not typically alter following this type of training, it is suggested that a reduction in resting BP would more likely be mediated by a reduction in TPR (Millar et al 2013b); however, the possibility of a change in Q cannot be overlooked (Wiley et al 1992). Despite the importance of these variables, only two published studies to date have measured both of these parameters preand post-IET, although no statistically significant changes in Q or TPR were detected despite the fact that resting BP was reduced (Devereux et al 2010;Wiles et al 2010). Further research is required to ascertain whether one or both of these variables regulate a reduction in resting BP.…”

Effect of isometric exercise on resting blood pressure: a meta analysis

“…For two papers, 11,13 the required information was not available and was therefore estimated 14 using the covariance from another study. 12 Changes in resting systolic blood pressure Figure 2 summarizes the effects of isometric exercise on resting systolic blood pressure for the individual trials and the mean overall effect from the metaanalysis. Each trial individually reported a significant reduction in systolic blood pressure with isometric exercise with a mean reduction of 10.4 mm Hg from the meta-analysis.…”