Association of sitting time and breaks in sitting with muscle mass, strength, function, and inflammation in community-dwelling older adults.

The mechanisms through which excessive sitting time impacts health are important to understand. This study found that each hour of sitting per day was not associated with physical function, although associations with poor body composition were observed. Reducing sitting time for improved weight management in older adults needs further exploration. INTRODUCTION: To examine the association of sitting time and breaks in sitting time with muscle mass, strength, function, and inflammation in older Australians. METHODS: Data from the thigh-worn activPAL3™ monitor (7-day continuous wear) was used to derive time spent sitting (hours) and total number of sit-stand transitions per day. Body composition (dual energy X-ray absorptiometry), lower-body muscle strength, function (timed up-and-go [TUG], 4-m gait speed, four square step test, 30-second sit-to-stand), and serum inflammatory markers (interleukin-[IL-6], IL-8, IL-10, tumor necrosis factor-alpha [TNF-α], and adiponectin) were measured. Multiple regression analyses, adjusted for age, sex, ethnicity, education, employment status, marital status, number of prescription medications, smoking status, vitamin D, and stepping time, were used to assess the associations. RESULTS: Data from 123 community-dwelling older adults (aged 65-84 years, 63% female) were used. Total daily sitting time was associated with lower percentage lean mass (ß [95%CI], - 1.70% [- 2.30, - 1.10]) and higher total body fat mass (2.92 kg [1.94, 3.30]). More frequent breaks in sitting time were associated with a 45% reduced risk of having pre-sarcopenia (OR = 0.55; 95% CI 0.34, 0.91; model 1), defined as appendicular lean mass divided by BMI. No significant associations were observed for sitting time or breaks in sitting with measures of muscle strength, function, or inflammation. CONCLUSION: In older community-dwelling adults, greater sitting time was associated with a lower percentage lean mass, while more frequent breaks in sitting time were associated with lower odds of having pre-sarcopenia. This suggests that reducing sedentary time and introducing frequent breaks in sedentary time may be beneficial for improving body composition in healthy older adults.

Associations between sedentary behaviour and body composition, muscle function and sarcopenia in community-dwelling older adults.

SUMMARY: While previous studies have reported detrimental associations of sedentary behaviours with cardiometabolic disorders and mortality, in this study, we report that higher levels of sitting time were associated with a greater risk of sarcopenia, with increased television (TV) viewing negatively associated with lean mass, independent of physical activity. INTRODUCTION: Sedentary behaviour has been linked to cardiometabolic disorders and mortality, but little is known about its effects on musculoskeletal health and function. This study investigated the relationship between total sitting and TV viewing time on sarcopenia and its determinants (muscle mass, strength and function) in older adults. METHODS: This cross-sectional study included 162 community-dwelling men and women aged 60 to 86 years who had complete assessment of total body and regional lean mass (LM) and fat mass (dual-energy X-ray absorptiometry (DXA)), lower limb muscle strength, power and functional performance. Sarcopenia was defined as the lowest sex-specific quartile for relative appendicular LM plus muscle strength and/or gait speed. Total sitting and TV viewing time were self-reported using a validated questionnaire. A sitting fragmentation ratio, as an index of breaks in sitting time, was calculated as the number of sitting bouts divided by total sitting time. RESULTS: Greater overall sitting time was associated with an increased risk of sarcopenia; for each 1-h increment, the risk increased by 33% [odds ratio 1.33 (95% confidence interval (CI) 1.05, 1.68)], independent of physical activity and other lifestyle and confounding factors. TV viewing time was associated with lower total body and leg LM after adjusting for various confounders and fat mass. There were no associations between total sitting or TV viewing time or the fragmentation ratio with any other measure. CONCLUSION: Higher levels of sedentary behaviour in older adults were associated with reduced muscle mass and an increased risk of sarcopenia in community-dwelling older adults, independent of physical activity.

Effects of a Multi-component, Resistance-Based Exercise Program Combined with Additional Lean Red Meat on Health-Related Quality of Life in Older Adults: Secondary Analysis of a 6-Month Randomized Controlled Trial.

OBJECTIVES: To assess whether consumption of lean red meat on three exercise training days per week can promote greater improvements than exercise alone in health-related quality of life (HR-QoL) in community-dwelling older adults. DESIGN: This study is a secondary analysis from a 6 month, two-arm, parallel randomized controlled trial conducted in 2014 and 2015. SETTING: Community-dwelling older adults living in metropolitan Melbourne, Australia. PARTICIPANTS: One hundred and fifty-four men and women aged ≥65 years. INTERVENTION: All participants were enrolled in a multi-component, resistance-based exercise program (3 d/week) and randomly allocated to either a group asked to consume lean red meat (2x80g cooked servings/day) on each of the three training days (Ex+Meat, n=77) or a control group asked to consume one serving of carbohydrates (1/2 cup rice/pasta or 1 medium potato; Ex+C, n=77). MEASUREMENTS: HR-QoL was assessed using the Short-Form (SF)-36 health survey. RESULTS: Overall 62% of the participants were female, the mean age was 70.7 years (range 65 to 84 years), approximately 67% of participants were classified as either overweight or obese, and the average number of chronic conditions was two. A total of 145 participants (94%) completed the study. Mean baseline HR-QoL scores were comparable to the mean for the Australian population [Global HR-QoL (mean ± SD): Ex+Meat, 49.99 ± 6.57; Ex+C, 50.49 ± 5.27]. General Linear Mixed Models examining within and between group changes over time revealed that after 6 months, there were no within-group changes in either Ex+Meat or Ex+C nor any between-group differences for any measure of HR-QoL, with the exception that the mental health subscale improved in Ex+C versus Ex+Meat [net difference for change, -2.32 (95% CI), -4.73, 0.09, P=0.048] after adjusting for relevant covariates and the physical function subscale improved in Ex+Meat relative to baseline [mean change (95% CI), 1.88 (0.37, 3.39), P=0.011]. CONCLUSION: A multi-component resistance-based training program performed with and without the provision of lean red meat in line with current Australian dietary guidelines on each of the three training days, did not improve HR-QoL in healthy community-dwelling older adults.