Intensity Matters for Musculoskeletal Health: A Cross-Sectional Study on Movement Behaviors of Older Adults from High-Income Scottish and Low-Income South African Communities

Abstract

This study aimed to investigate differences in physical activity (PA) patterns and the associations between objectively measured 24-h movement behaviors and musculoskeletal measures (muscle strength, muscle mass, physical performance, and bone mineral density) in a high-income and a low-income community. This cross-sectional study recruited independent living older adults aged 60–85 years from high-income Scottish (n = 150) and low-income South African (n = 138) settings. Participants completed demographic and health questionnaires, and testing included body composition and bone mineral density (dual energy X-ray absorptiometry), physical performance (grip strength, gait speed), and PA (accelerometry). Participants accumulated similar amounts of weekly total PA, however, the Scottish cohort engaged in more moderate-to-vigorous intensity PA (MVPA) and sedentary behavior (SB), while the South African cohort spent more time sleeping and in light intensity PA (LPA). From compositional data analysis, more time spent in MVPA relative to the other movement behaviors was positively associated with higher muscle mass (p < 0.001) and strength (p = 0.001) in the Scottish cohort. Conversely, more time spent in MVPA was associated with faster gait speed (p < 0.001) and greater hip bone mineral density (p = 0.011) in the South African cohort. Our findings confirm the beneficial role of MVPA in both high- and low-income cohorts, however, the relationship MVPA had with components of musculoskeletal health in older adults differed between settings.

Cross‐sectional interactive associations of physical activity and sedentary behaviour with physical capacity across adulthood

“…This is illustrated by the intersection of the regression lines in Figure 2 and by the unexpected positive association between SB duration and lower‐limb muscle power observed in young subjects ( Table S2 ). The lack of associations with the other outcomes is in accordance with published work on gait speed 17 , 18 , 29 and handgrip strength, 17 , 18 , 24 , 28 although the data on V̇O 2 max remain contrasted. 5 , 8 …”

“…This is illustrated by the intersection of the regression lines in Figure 2 and by the unexpected positive association between SB duration and lower-limb muscle power observed in young subjects (Table S2). The lack of associations with the other outcomes is in accordance with published work on gait speed 17,18,29 and handgrip strength, 17,18,24,28 although the data on V ˙O2 max remain contrasted. 5,8 Our work is one of the few that considers the influence of the interaction between MVPA and SB on the associations between age and several physical outcomes throughout adulthood.…”

“…Notably, this age‐moderating effect was observed at the age of 64, which suggests that late adulthood might be a critical life period when MVPA and SB seem to further impact physical function. This age specificity may explain the disparate results reported from previous studies that did not specifically examine the age range of significance regarding the relationship of handgrip strength with PA, 17,20,22,24–26 SB 17,18,20,24,25,28 and their interactions 33 . The lack of interaction effect on the other outcomes is in accordance with some 33 but not all 10 published accelerometry‐based data on gait speed and questionnaire‐based data on muscle strength 23 in middle‐aged and older adults.…”

“… 2 Over the past decades, numerous studies conducted in young (<40 years), middle‐aged (40–59 years) or older adults (60+) demonstrated that higher levels of PA were associated with better aerobic fitness 3 , 4 , 5 , 6 , 7 , 8 , 9 and faster gait speed. 6 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 However, investigations conducted on muscle power, 6 , 10 , 12 , 13 , 18 , 20 , 21 lower‐limb 6 , 12 , 22 , 23 , 24 and handgrip 17 , 18 , 20 , 22 , 24 , 25 , 26 muscle strength provided mixed results.…”

“…Studies conducted in young adults reported lower cardiorespiratory fitness with increasing levels of SB. 8 Studies involving middle‐aged and old adults consistently reported no associations between handgrip strength and SB, 17 , 18 , 24 , 25 , 28 but mixed results regarding gait speed, 10 , 12 , 17 , 18 , 28 , 29 , 30 lower‐limb muscle strength 12 , 23 , 24 and estimated lower‐limb muscle power. 9 , 10 , 12 , 13 , 18 , 20 , 24 , 29 , 30 , 31 Other studies, including subjects from the whole adult lifespan, indicated that the levels of SB were negatively associated with lower‐limb muscle strength, 22 but not with aerobic fitness.…”