In a recent study published in the journal Scientific Reports, researchers performed a meta-analysis to elucidate the effects of exercise training on stress-related blood pressure (BP) reactivity. Their results show that regular aerobic exercise helps lower systolic BP responses to adult stressors, especially in hypertensive individuals.
Exercise vs. stress
Day-to-day life is the source of a myriad of physical, mental, and emotional stressors, all of which are known to affect our internal stability (homeostasis) profoundly. Previous works have investigated the effects of stressors on the cardiovascular system. Stress-related BP variations have been identified as predictors of future hypertension, rapid aging, and cardiovascular trauma.
Stress is a complex, multidimensional conflux of factors threatening homeostasis. Research has suggested that physical and mental stressors might trigger increased BP via hormone, neural network, or autonomic system alterations. Health practitioners often prescribe exercise training as a non-pharmacological intervention against high BP, with previous research showing attenuated peak BP reactivity post workouts (acute exercise).
The literature, however, remains devoid of work on non-aerobic exercise and the effects of physical fitness (prolonged exercise training) on BP responses to stressors. The present work aims to fill these knowledge gaps using a meta-analytic approach to investigate if exercise training can have effects similar to acute exercise. Can routine and regular exercise be used not only as a therapy post-stress but also as a preventive measure against the cardiovascular impacts of stressors?
About the study
Researchers first scanned five electronic databases, identifying 5,058 publications matching their essential exercise and blood pressure monitoring requirements. These publications were scrutinized, and of them, 23 full publications and one conference abstract were chosen to comprise the final dataset.
All papers were reviewed in duplicate by independent researchers. The meta-analyses comprised 1,121 individuals advised between six and 52 weeks of moderate to high-intensity exercise. Exercise duration was found to average 50 minutes and was repeated three to four times a week. The ratio of male to female patients was 1.65:1. Almost 22% of participants were classified as hypertensive, over 61% were normotensive, and the remaining were unclassifiable due to study-specific missing data.
The most prescribed exercise mode was aerobic training, with 21 out of the 23 studies referencing the same. This was followed by resistance training (five studies), yoga (two studies), and isometric handgrip training (one study). The almost ubiquitous take-home of all studies was that exercise is good – 10 studies found significant reductions in diastolic BP (DBP), nine in systolic BP (SBP), and one in mean BP reactivity. Only one paper found a negative association between DBP and yoga.
The most frequent stressor used in these papers was the arithmetic task, which the authors caution against due to it not reflecting daily stressors accurately.
Meta-analyses found that 64% of studies showed positive outcomes wherein exercise training decreased SBP or DBP. Studies that showed peak stress associated with SBP elucidated exercise had moderate favorable effects compared with studies that measured and reported variation in baseline BP, which had a null impact.
This may be an indication that physical exercise, more than reducing the stress response, lowers resting BP and given the same magnitude of stress response, lowers peak BP.”
Despite these results, reducing BP is still paramount, given its association with the risk of future cardiovascular injury, including stroke. Results also suggest that exercise can have varying anti-stress effects depending on the type of stressor – physical stressors were shown to act via arteriolar vasoconstriction. In contrast, a mental stressor would result in no change in blood volume but significant changes in heart and pulse rate and pressure.
Previous studies have shown that variance in patients’ familiarity with the tests, self-efficacy, and the duration post-exercise that readings are noted could introduce significant heterogeneity in results. Additional work on different stressor modes, investigations on non-aerobic exercise, along with standardized test protocols could help progress this field further.
Unlike previous work, the current research did not find strong associations between age-class, and sex to the benefits of exercise. While younger groups showed no effects compared to the moderate impact seen in older groups, differences between more senior age classes were insignificant. This study also found more significant improvements in female stress response BP post-exercise, compared to previous literature, which suggested males benefitted more.
Finally, despite little research comparing trends in hypersensitive versus normotensive patients, the present research found evidence for exercise effects being the greatest for these at-risk individuals. Hypertensive individuals were found to have lower cardiac output and more significant vasculature than their normotensive counterparts. The relative contributions of exercise and anti-hypertensive drugs must be investigated in future work.
The present meta-analysis provides evidence which suggests that aerobic exercise can reduce systolic blood pressure responses to lab-based stress tests. These results are especially important for individuals with hypertensive histories and those over 35. While having the limitation of being restricted to secondary data, this study forms the basis for future work.
Future studies should consider exploring the different aspects of the population’s characteristics, type of stress testing, and other exercise modalities, especially resistance training.”