Associations of altitude, physical activity, and body mass index with blood pressure components and grip strength in older adults with elevated blood pressure living at 3100–4500 m in Tibet: a cross-sectional study

Abstract

High-altitude environments may influence cardiovascular and muscle function in older adults. We examined blood-pressure components and grip strength across three Tibetan altitude sites and their associations with residential altitude, physical activity, and body mass index (BMI) in older adults with elevated blood pressure. This cross-sectional secondary analysis used de-identified National Physical Fitness Monitoring data from Linzhi (3100 m), Lhasa (3650 m), and Nagqu (4500 m). Separate multivariable linear regression models were fitted with systolic blood pressure (SBP), diastolic blood pressure (DBP), and grip strength as outcomes; residential altitude, BMI, physical-activity frequency, and session duration were the main independent variables, with adjustment for age and sex. HC3 robust standard errors were used for inference. The analytic sample included 454 community-dwelling adults aged 60–69 years with elevated blood pressure. Across the three fixed sites, the continuous site/altitude term was associated with higher SBP (β = 4.51 mmHg per 1000 m, 95% CI 2.82 to 6.19), higher DBP (β = 1.98 mmHg per 1000 m, 95% CI 0.61 to 3.36), and lower grip strength (β = -3.25 kg per 1000 m, 95% CI -4.38 to -2.11). Higher BMI was associated with higher DBP (β = 0.27 mmHg per kg/m², 95% CI 0.06 to 0.47). Physical-activity frequency and session duration were not clearly associated with SBP or grip strength; the only nominally significant physical-activity coefficient was lower DBP in the ≥ 60 min/session group ( n = 7), which was not interpreted because of the sparse group. Within this outcome-selected analytic subset of older adults with elevated blood pressure at three Tibetan sites, the continuous site/altitude term was associated with higher SBP and DBP and lower grip strength, and BMI was associated with higher DBP. Physical-activity estimates were imprecise. Because each altitude corresponded to one site and the SBP–site/altitude and BMI–DBP findings were site-sensitive, the findings are conditional on these three fixed sites and should not be interpreted as independent altitude effects or generalized to unselected older populations. Cross-sectional summary of the study population, shared predictor set, three outcome models, and principal associations among older adults with elevated blood pressure. The continuous site/altitude term was associated with higher SBP, higher DBP, and lower grip strength; BMI was associated with higher DBP; and physical-activity estimates were imprecise. Because each altitude corresponded to one site, the site/altitude estimates are conditional on the three fixed sites and do not identify independent altitude effects; the analytic sample was selected on elevated measured BP at the same monitoring visit. HC3 robust standard errors were used. Created in BioRender. Liang, W. (2026) https://BioRender.com/vad19s6 .