Physical Activity to Prevent and Treat Hypertension: A Systematic Review.

Abstract

Dear Editor-in-Chief, We read with interest the article by Pescatello et al. (1) within which they state the following: These investigators were unable to explain reasons for larger reductions in SBP (systolic blood pressure) among adults with normal BP compared with adults with hypertension… Therefore, no conclusions can be made about the antihypertensive benefits of isometric resistance training. We believe this statement is compromised for several reasons. First, Pescatello et al. (1) based their comment solely on the meta-analysis by Carlson et al. (2), so their systematic search missed the larger, more robust 2016 meta-analysis by Inder et al. (3). Inder’s analysis (3) and the recent individual patient data meta-analysis of 326 participants (4) both confirm the unequivocal antihypertensive benefits of isometric resistance training (IRT), meaning there exists three congruent meta-analyses. As of June 2019, there were 19 published controlled trials investigating the antihypertensive effects of IRT; no fewer than 17 of these show significant benefit. The only two exceptions possess obvious trial design flaws including; unmatched aerobic exercise and IRT groups at baseline (e.g., 9 mm Hg difference in SBP), underpowered sampling (N = 5), selection bias and incorrect reporting of statistical significance. The evidence for antihypertensive benefit from IRT is accumulating quickly and includes recent international hypertension guideline changes (5,6). Other bodies, such as the recent joint guideline from the American Heart Association/American College of Cardiology (6), after correctly appraising the published evidence, now endorse IRT as an adjunct antihypertensive treatment. Exercise and Sport Science Australia (7), and Canadian hypertension guidelines (5) also recommend IRT for management of hypertension. One complicating factor may be intuitive concerns about IRT safety, because of the potential for a pressor response. However, cardiovascular responses to aerobic exercise and IRT show double product, a surrogate of myocardial oxygen consumption, is lower by a third during IRT (8), suggesting that safety is less concerning than during aerobic exercise. We acknowledge that a large (N > 200), well-designed randomized, controlled trial remains missing from the literature. Such a trial would allow possible medication–IRT interactions to be identified and a health economics evaluation, lack of trial funding currently precludes this. Finally, the explanation for the larger blood pressure reduction in normotensive versus hypertensive participants is simply explained by the fact that the latter were medicated and possess less potential to regress to the mean. We view Pescatello et al’s systematic search (1) and therefore the data interpretation to be incomplete and the subsequent, dismissal of the highest possible level and strength of evidence to be imprudent and contradictory to the current best evidence. Neil A. Smart School of Science and Technology University of New England Armidale NSW, AUSTRALIA Reuben Howden Department of Kinesiology University of North Carolina at Charlotte Charlotte, NC Veronique Cornelissen Department of Rehabilitation Sciences KU Leuven Leuven, BELGIUM Robert Brook Division of Cardiovascular Medicine University of Michigan Ann Arbor, MI Cheri McGowan Division of Cardiovascular Medicine University of Michigan Ann Arbor, MI Department of Kinesiology University of Windsor, CANADA Philip J. Millar Department of Human Health and Nutritional Sciences University of Guelph CANADA Raphael Ritti-Dias Post-Graduate Program in Rehabilitation Science University Nove de Julho São Paulo, BRAZIL Anthony Baross Department of Sport Science University of Northampton Northamptonshire, UNITED KINGDOM Debra J. Carlson School of Health, Medical and Applied Sciences Central Queensland University North Rockhampton, QLD, AUSTRALIA Jonathon D. Wiles School of Human and Life Sciences Canterbury Christ Church University UNITED KINGDOM Ian Swaine Faculty of Engineering and Science University of Greenwich Kent, UNITED KINGDOM