This meta-analysis sought to: quantify the effects of isometric resistance training (IRT) on the magnitude of change in systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP) and resting heart rate in adults; and examine whether the magnitude of change in SBP, DBP, MAP and heart rate was different with respect to the patient demographic characteristics and IRT parameters. To be included in the meta-analysis, studies had to be randomized controlled trials lasting 2 or more weeks, investigating the effects of IRT on blood pressure in adults. The methodological quality of the studies selected was evaluated using the PEDro scale. For each main outcome measure, an average effect size and its respective 95% confidence intervals were calculated.
A total of 16 articles (492 participants) fulfilled the selection criteria (mean quality score in the PEDro scale of 5.9). Compared with control groups, IRT groups showed statistically significant (P < 0.05) and clinically relevant (>2 mmHg) positive effects on the SBP (−5.23 mmHg) and MAP (−2.9 mmHg). IRT groups also showed statistically significant, but not clinically relevant reduction in DBP (−1.64 mmHg). Furthermore, IRT groups did not report any statistically significant and clinically relevant (>5 bpm) effect on resting heart rate (−0.08 bpm).
The analysis of moderator variables showed that none of them exhibited a statistically significant relationship with the positive effects of IRT for lowering blood pressure. Therefore, IRT may be considered an appropriate nonpharmacologic treatment for lowering SBP and MAP.
aSports Research Centre, Miguel Hernández University of Elche, Alicante
bUniversidad Internacional Isabel I Castilla, Burgos, Spain
cSchool of Physical Education, Faculty of Sport, Health and Social Care, University of Gloucestershire, Gloucester, UK
dDepartment of Basic Psychology & Methodology, Faculty of Psychology, University of Murcia, Murcia, Spain
Correspondence to Francisco Ayala, Sports Research Centre, Miguel Hernández University of Elche. Avda. de la Universidad s/n. 03202 Elche, Alicante, Spain. Tel: +34 965222401; fax: +34 965222409; e-mail: Franciscoayalarodríguez@gmail.com
Abbreviations: AHA, American Heart Association; bj, regression coefficient for the predictor variable; BP, blood pressure; CI, confidence interval; D+, effect size; DBP, diastolic blood pressure; DRT, dynamic resistance training; ICC, intra-class correlation coefficient; IRT, isometric resistance training; k, number of studies; MAP, mean arterial pressure; MVC, maximal voluntary contraction; QE, statistic for testing the model misspecification; QR, statistic for testing the statistical significance of the predictor variable; R2, proportion of variance explained by the predictor variable; RCTs, randomized control trials; SBP, systolic blood pressure; SDC, supplemental digital content; SD, standard deviation; SE, standard error
Received 31 July, 2018
Accepted 18 November, 2018
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