Muscle-strengthening exercise and prevalent hypertension among 1.5 million adults: a little is better than none.

Background: Clinical evidence suggests that muscle-strengthening exercise (using weight machines/body weight exercises) may be an important antihypertensive lifestyle therapy. However, epidemiological research on the association between muscle-strengthening exercise and hypertension is limited. We conducted the first population-level study describing the associations between muscle-strengthening exercise and prevalent hypertension among a large sample of US adults.
Methods: In this cross-sectional study, data were pooled from four US health surveillance surveys (2011-2017) (n = 1 539  309, aged ≥18 years). Muscle-strengthening exercise frequency and self-reported clinically diagnosed hypertension (n = 431 313; 28%) were assessed using the same items across each survey. Generalized linear models using Poisson regression with robust error variance were used to calculate the prevalence ratios of hypertension (outcome variable) across muscle-strengthening exercise [exposure variables: 0 (reference); 1 to ≥7 times/week), adjusting for potential cofounders.
Results: Compared with those doing none, the adjusted prevalence ratios for hypertension were 0.67 (95% CI: 0.66-0.68), 0.67 (95% CI: 0.67-0.68), 0.70 (95% CI: 0.69-0.70), 0.61 (95% CI: 0.60-0.63), 0.62 (95% CI: 0.61-0.64), 0.60 (95% CI: 0.58-0.62) and 0.83 (95% CI: 0.82-0.84) among the groups engaging in muscle-strengthening exercise one, two, three, four, five, six, and at least seven times/week, respectively. Associations remained after stratification for sociodemographic factors (age, sex), lifestyle characteristics (aerobic exercise, BMI, self-rated health, smoking, alcohol) and comorbidities (e.g. arthritis, diabetes, depression).
Conclusion: Among over 1.5 million adults, compared with those doing none, any weekly frequency in muscle-strengthening exercise was associated with a lower prevalence of hypertension. Longitudinal studies and large-scale muscle-strengthening exercise interventions with population representative samples are needed to confirm these preliminary cross-sectional observations.