Originally published by 2 Minute Medicine® (view original article). Reused on AccessMedicine with permission.

1. For older adults with overweight or obesity, and metabolic syndrome, replacing 30 minutes of inactive time with moderate to vigorous physical activity was associated with a decrease in body fat and increase in muscle mass.

Evidence Rating Level: 2 (Good)

Aging tends to lead to changes in body composition, including loss of muscle mass and adipose accumulation in central body areas: This could lead to mobility issues and chronic diseases, such as cardiovascular conditions and diabetes. Although physical activity (PA) is well known to combat these body composition changes, previous research has not fully elucidated the optimal relationship between PA and sedentary behaviour (SB), as well as the extent of PA that needs to be done to make a significant improvement in body composition. In this prospective cohort study, researchers investigated body composition changes associated with time spent in PA and SB, as well as the effect of replacing SB with PA at varying intensities or with time in bed. The study population included 1,565 participants (average age 65, 48% women) from Spain who were overweight, obese, or had 3 or more components of metabolic syndrome. In addition to self-reported PA and SB data collected for a year, accelerometer data (to measure PA and SB) was collected for one week at baseline, 6 months follow-up, and 12 months follow-up. Data on body fat mass and body muscle mass were collected from DXA scanners at those same three time points. The results demonstrated that, after adjusting for confounders, a 30 minute daily increase in total PA and moderate to vigorous physical activity (MVPA) were significantly correlated with a decrease in body fat (β coefficient − 0.07%, 95% CI − 0.10 to 0.04% for total PA; β -0.08%, 95% CI -0.11 to -0.04% for MVPA) and an increase in muscle mass (β 0.07%, 95% CI 0.04 to 0.10; β 0.07%, 95% CI 0.04 to 0.10 respectively). Low levels of PA (LPA) did not have significant associations. Furthermore, replacing 30 min daily of inactive time with time in bed, LPA, and MVPA were all associated with a decrease in body fat (β -0.09%, -0.13%, and -0.54% respectively) and an increase in muscle mass (β 0.08%, 0.12%, and 0.51% respectively). Overall, this study demonstrated the positive impact of just 30 minutes of MVPA can have on fat composition and muscle mass in older adults, which can help health care providers better inform and motivate patients who have overweight, obesity, and/or metabolic syndrome.

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