Is stretching a good way to manage hypertension?

While brisk walking has been known to have benefits for blood pressure (BP), it appears that stretching may be a better option for managing moderately high BP, a study suggests.

The benefits of increased physical activity (PA) for BP has long been established. [Int J Behav Nutr Phys Act 2010;7:39] Most studies recommend aerobic exercise, but there is also evidence reflecting the capability of stretching to reduce arterial stiffness, thereby improving blood flow and increasing activation of the parasympathetic nervous system (PSNS), which consequently leads to BP reduction. [Int Heart J 2013;54:59-63; Eur J Sport Sci 2017;17:586-592]

“If stretching exercise can indeed reduce BP, it would allow an additional option for people who need to reduce BP, or it could be added to aerobic exercise routines to provide greater reduction in BP,” said the researchers.

Forty adults (median age 61.6 years) with high-normal BP (130/85–139/89 mmHg) or stage I hypertension* (140/90–159/99 mm Hg) were randomized 1:1 to participate in a daily 30-minute stretching** or brisk walking*** exercise programme 5 days/week for 8 weeks. [J Phys Act Health 2020;doi:10.1123/jpah.2020-0365]

Compared with brisk walking, stretching exercises led to greater drops in BP (mean adjusted changes, –4 vs 1 mm Hg; p=0.035 [sitting systolic], –6 vs 0 mm Hg; p=0.0053 [supine diastolic], and –2 vs 5 mm Hg; p=0.012 [night-time diastolic]) and mean arterial pressure (mean adjusted changes, –4 vs 0 mm Hg; p=0.028 [sitting], –5 vs –1 mm Hg; p=0.018 [supine], and –3 vs 5 mm Hg; p=0.026 [night-time]).

“Our study is the first to show that [an 8-week] stretching programme is more effective than a walking programme for reducing BP in people with moderately elevated BP,” said the researchers.

These may be attributed to several physiologic mechanisms, they noted. “When muscle is stretched … blood vessels are also stretched. This may induce structural changes within blood vessels that can affect blood vessel diameter or decrease arterial stiffness to reduce resistance to flow which, in turn, reduces BP.”

In a preclinical study, stretching of the lower hind limbs of older mice led to increased vasodilation, capillarization, VEGF^# production, and blood flow. [J Physiol 2018;596:1903-1917] “[These] adaptations … led to decreased vascular resistance, which could potentially decrease BP,” they continued.

“[A]n acute bout of stretching [may also trigger] reduced SNS activation in conjunction with increased PSNS activation. This would decrease vasoconstriction and increase vasodilation, reducing resistance to blood flow, causing a decrease in BP,” they added.

However, given the small study sample and the lack of statistical significance in some of the results, the investigators called for larger randomized trials to ascertain the findings. “A larger sample size would have permitted inclusion of other covariates (ie, sodium intake, age, and PA outside the exercise programme).”

Although PA changes were evaluated using the PASE^## questionnaire, no significant between-group changes were observed in terms of PA levels outside the intervention regimen. Given its probable effect, PA outside of the programme should also be explored in future trials using more accurate PA assessments (eg, accelerometers, pedometers). Other limitations that should be taken into context are the lack of evaluation on changes in arterial stiffness, vasodilation, or PSNS activation.

“[Nonetheless,] this finding is important as it offers people a greater number of exercise options for reducing BP. Considering that walking is beneficial for reducing other cardiovascular risk factors … it might be best to add a comprehensive stretching routine to aerobic exercise for overall cardiovascular benefit,” they concluded.