Edwards Jamie J, Wiles Jonathan, O'Driscoll Jamie
School of Psychology and Life Sciences, Canterbury Christ Church University, Kent, UK.
J Hypertens. 2022 Nov 1;40(11):2299-2306. doi: 10.1097/HJH.0000000000003261. Epub 2022 Aug 8.
Isometric exercise training (IET) is established as an effective antihypertensive intervention. Despite this, the physiological mechanisms driving blood pressure (BP) reductions following IET are not well understood. Therefore, we aimed to perform the first meta-analysis of the mechanistic changes measured following IET.
PubMed, Cochrane library and SPORTDiscus were systematically searched for randomized controlled trials published between January 2000 and December 2021 reporting the effects of IET on resting BP and at least one secondary mechanistic parameter following a short-term intervention (2-12 weeks).
Eighteen studies with a pooled sample size of 628 participants were included in the final analysis. IET produced significant reductions in resting systolic and diastolic BP of 9.35 mmHg (95% confidence interval [CI] = -7.80 to -10.89, P < 0.001) and 4.30 mmHg (CI = -3.01 to -5.60, P < 0.001), respectively. Mechanistically, IET produced a statistically significant reduction in resting heart rate (mean difference [MD]: -1.55 bpm, CI = -0.14 to -2.96, P = 0.031) and a significant increase in stroke volume (MD: 6.35 ml, CI = 0.35 to 12.60, P = 0.038), with no significant change in cardiac output. Conversely, total peripheral resistance (TPR) significantly decreased following IET (MD: -100.38 dyne s -1 cm 5 , CI = -14.16 to -186.61, P = 0.023), with significant improvements in the low frequency to high frequency heart rate variability ratio (MD: -0.41, CI = -0.09 to -0.73, P = 0.013) and baroreceptor reflex sensitivity (MD: 7.43 ms/mmHg, P < 0.001).
This work demonstrates that a reduction in TPR, potentially mediated through enhanced autonomic vasomotor control, is primarily responsible for BP reductions following IET. Furthermore, this novel analysis suggests wall squat interventions to be the most effective IET mode, with clinically relevant differences in BP reductions compared to handgrip and leg extension IET; although future direct comparative research is required.
等长运动训练（IET）已被确立为一种有效的降压干预措施。尽管如此，IET后导致血压（BP）降低的生理机制尚不完全清楚。因此，我们旨在对IET后测量的机制变化进行首次荟萃分析。
系统检索PubMed、Cochrane图书馆和SPORTDiscus，查找2000年1月至2021年12月期间发表的随机对照试验，这些试验报告了短期干预（2 - 12周）后IET对静息血压和至少一项次要机制参数的影响。
最终分析纳入了18项研究，汇总样本量为628名参与者。IET使静息收缩压和舒张压分别显著降低9.35 mmHg（95%置信区间[CI]= -7.80至-10.89，P < 0.001）和4.30 mmHg（CI = -3.01至-5.60，P < 0.001）。从机制上讲，IET使静息心率有统计学意义的降低（平均差[MD]：-1.55次/分钟，CI = -0.14至-2.96，P = 0.031），每搏输出量显著增加（MD：6.35 ml，CI = 0.35至12.60，P = 0.038），心输出量无显著变化。相反，IET后总外周阻力（TPR）显著降低（MD：-100.38达因·秒·厘米⁻⁵，CI = -14.16至-186.61，P = 0.023），低频与高频心率变异性比值（MD：-0.41，CI = -0.09至-0.73，P = 0.013）和压力感受器反射敏感性显著改善（MD：7.43毫秒/毫米汞柱，P < 0.001）。
这项研究表明，TPR的降低可能是通过增强自主血管运动控制介导的，这是IET后血压降低的主要原因。此外，这项新的分析表明，靠墙蹲起干预是最有效的IET模式，与握力和腿部伸展IET相比，在血压降低方面存在临床相关差异；尽管未来需要进行直接的比较研究。
