Light Intensity Physical Activity and Sedentary Behavior in Relation to Body Mass Index and Grip Strength in Older Adults: Cross-Sectional Findings from the Lifestyle Interventions and Independence for Elders (LIFE) Study

Abstract

BackgroundIdentifying modifiable determinants of fat mass and muscle strength in older adults is important given their impact on physical functioning and health. Light intensity physical activity and sedentary behavior are potential determinants, but their relations to these outcomes are poorly understood. We evaluated associations of light intensity physical activity and sedentary time—assessed both objectively and by self-report—with body mass index (BMI) and grip strength in a large sample of older adults.MethodsWe used cross-sectional baseline data from 1130 participants of the Lifestyle Interventions and Independence for Elders (LIFE) study, a community-dwelling sample of relatively sedentary older adults (70-89 years) at heightened risk of mobility disability. Time spent sedentary and in light intensity activity were assessed using an accelerometer worn for 3–7 days (Actigraph GT3X) and by self-report. Associations between these exposures and measured BMI and grip strength were evaluated using linear regression.ResultsGreater time spent in light intensity activity and lower sedentary times were both associated with lower BMI. This was evident using objective measures of lower-light intensity, and both objective and self-reported measures of higher-light intensity activity. Time spent watching television was positively associated with BMI, while reading and computer use were not. Greater time spent in higher but not lower intensities of light activity (assessed objectively) was associated with greater grip strength in men but not women, while neither objectively assessed nor self-reported sedentary time was associated with grip strength.ConclusionsIn this cross-sectional study, greater time spent in light intensity activity and lower sedentary times were associated with lower BMI. These results are consistent with the hypothesis that replacing sedentary activities with light intensity activities could lead to lower BMI levels and obesity prevalence among the population of older adults. However, longitudinal and experimental studies are needed to strengthen causal inferences.

Daily physical activity impact in old women bone density and grip strength

“…It means that if the activity performed is in a moderate-to-high intensity, muscle contraction is preserved in a normal range. This result is parallel to other studies correlations between daily intensity accelerometry and muscle power and strength in the lower extremity (10)(11)(12), and handgrip strength (11,13) in elder. It appears that accelerometer location has not meaningful implications regarding strength outcomes.…”

“…With respect to daily physical activity impact in specific outcomes such as osteoporosis or sarcopenia in older people, previous investigations have highlighted an association between habitual physical activity and the lower extremity muscle power (10)(11)(12) and handgrip strength (11,13). In contrast, the relationship between dual-energy X-ray absorptiometry and daily physical activity accelerometry brings clear inverse correlation between intensity and adiposity (12,14) but associations regarding bone density markers are still not clear.…”

Sedentary time in older adults: a critical review of measurement, associations with health, and interventions

“…One study found no relationship between ST and grip strength34 while others found that the observed relationship between ST and function was not significant after adjustment for moderate-to-vigorous intensity physical activity (MVPA) 29 38. In contrast to the majority of findings, one study reported a positive association between ST and lower leg extensor power35; it was suggested that this was due to the potential training stimulus provided by the higher body mass index observed in more sedentary participants.…”

Associations Between Objectively Measured Physical Activity, Body Composition and Sarcopenia: Findings from the Hertfordshire Sarcopenia Study (HSS)

“…Several studies have explored the associations between objectively measured PA and measures of body composition and function [12–16]. For example, higher physical activity and low sedentary activity were associated with lower body mass index (BMI) in a cross-sectional analysis of the LIFE study [12].…”