Combined association of aerobic and muscle strengthening activity with mortality in individuals with hypertension

Physical activity (PA), encompassing both aerobic activity and muscle-strengthening activity (MSA), is crucial for preventing diseases and mortality. Current guidelines recommend at least 500 metabolic equivalent tasks (METs) per week of aerobic PA and MSA involving major muscle groups twice weekly. However, global adherence to these combined guidelines is low. Hypertension significantly contributes to global morbidity and mortality, and while PA guidelines for hypertensive individuals are similar to those for the general population, the combined impact of aerobic PA and MSA on mortality in this group remains understudied. Previous research has shown individual benefits of aerobic PA and MSA on mortality in hypertensive populations, but the combined effect is less clear. This study aimed to clarify the associations of hypertension and adherence to PA guidelines with all-cause and cardiovascular disease (CVD) mortality.

The benefits of physical activity in preventing various diseases and reducing mortality are well-established. Current PA guidelines recommend both aerobic and muscle-strengthening activities. While many studies highlight the benefits of aerobic PA, research on the combined effects of aerobic and muscle-strengthening activities on mortality, particularly in individuals with hypertension, is limited. Although some studies show inverse dose-response associations between each type of activity and mortality in hypertensive individuals, the combined impact remains unclear. This study addresses this gap by examining the combined effects of meeting both aerobic and muscle-strengthening activity guidelines on mortality risk in individuals with and without hypertension.

This study utilized data from the 2007-2013 Korea National Health and Nutrition Examination Survey (KNHANES), a nationally representative survey of the Korean population. The analysis included adult participants (aged 19+) with available blood pressure (BP) and PA measurements and mortality status (followed until 2019). Participants with self-reported cancers or CVDs, or those who died within the first year of follow-up, were excluded. Hypertension was defined as systolic BP ≥140 mmHg or diastolic BP ≥90 mmHg, or self-reported antihypertensive medication use. PA was assessed using self-reported questionnaires based on the International Physical Activity Questionnaire, categorizing participants into four groups based on adherence to guidelines for aerobic PA (≥500 METs-min/week) and MSA (≥2 days/week): neither, MSA only, aerobic PA only, and both. Mortality data were linked to KNHANES data using resident registration numbers. Covariates included age, sex, household income, education, marital status, smoking status, alcohol consumption, BMI, diabetes, and dyslipidemia. Cox proportional hazard models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for the association between hypertension, PA adherence, and all-cause and CVD mortality. Models were adjusted for potential confounders. Subgroup analyses were performed to examine the interaction between hypertension status and PA adherence. Sensitivity analyses excluded mortalities within two years of follow-up and included a stratified analysis by antihypertensive medication use among hypertensive individuals. All analyses were performed using R software (version 4.2.0), with statistical significance set at P<0.05.

Over a 9.2-year follow-up, 1948 deaths (419 CVD-related) occurred among 34,990 participants. Meeting both PA guidelines was associated with the lowest risk of all-cause and CVD mortality in the total sample, regardless of hypertension status. In individuals with hypertension, meeting aerobic PA guidelines only reduced the risk of both all-cause and CVD mortality by 24%. Meeting both guidelines further reduced these risks by 40% and 43%, respectively. However, meeting MSA guidelines only was not significantly associated with either all-cause or CVD mortality in this group. In non-hypertensive individuals, only meeting both PA guidelines, but not meeting either guideline alone, reduced CVD mortality risk. Table 1 presents baseline characteristics stratified by hypertension status and PA guideline adherence. Table 2 summarizes the associations between hypertension, PA, and mortality. The interaction between exposure and sex was not significant (P>0.05). Hypertension was associated with increased risk of all-cause and CVD mortality compared to non-hypertensive individuals. Higher levels of aerobic PA (≥1000 METs-min/week) were inversely associated with all-cause and CVD mortality. For MSA, 1 and 2–3 days/week were associated with reduced all-cause mortality.

This study provides strong evidence supporting the combined benefits of aerobic and muscle-strengthening activities on mortality risk, especially in individuals with hypertension. The findings highlight that simply meeting aerobic PA guidelines provides significant mortality reduction in hypertensive individuals, while the addition of MSA yields even greater benefits. The lack of significant mortality reduction associated with MSA alone in hypertensive individuals warrants further investigation to optimize MSA recommendations for this population. The study's findings are particularly relevant to Asian populations, where hypertension is a major health concern. The results contribute to a better understanding of the combined effects of PA on mortality and inform public health strategies aimed at reducing mortality risk in hypertensive populations.

This study demonstrates that meeting both aerobic PA and MSA guidelines is associated with the lowest mortality risk, particularly in hypertensive individuals. While aerobic PA alone provides significant benefits, combining it with MSA offers even greater protection. Future research should focus on determining optimal MSA dosages for hypertensive individuals to maximize health benefits and investigate the reasons for the lack of independent benefit observed from MSA alone in this population. These findings emphasize the importance of promoting combined PA strategies for improved health outcomes in individuals with hypertension.

This study relied on self-reported PA data, which may be subject to recall bias. The cross-sectional nature of the baseline data limits the ability to establish definitive causal relationships. The study population is specific to Korea, and the generalizability to other populations might be limited. The exclusion of participants with pre-existing CVD or cancer could limit the generalizability of the results to broader populations.