Expert Review
Conflicts of interest:
None
Take Home Message:
- The importance of including daily physical activity in place of sedentary behaviour.
- The additional benefits of moderate-to vigorous physical activity.
- The importance of seeking medical advice before commencing a physical activity programme
- The importance of working with qualified exercise prescribers when embarking on a new activity programme
Evidence Category:
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A: Meta-analyses, position-stands, randomized-controlled trials (RCTs)
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B: Systematic reviews including RCTs of limited number
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X
C: Non-randomized trials, observational studies, narrative reviews
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D: Case-reports, evidence-based clinical findings
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E: Opinion piece, other
Summary Review:
Introduction:
Authors highlight that although the relationship between physical activity (PA), sedentary behaviour (SB) and markers of obesity and body composition (BC) have been studied extensively, the balance between PA at different levels of intensity e.g. light physical activity (LPA) intensity and medium to vigorous activity (MVPA) intensity as well as SB in older, obese/overweight adults remains unclear.
Aim and Objectives:
This longitudinal, observational prospective study aimed to explore the relationships between PA and SB in an older population with Metabolic Syndrome (MetS) over a period of 12 weeks (n=1564).
The objectives were specifically to:
1. Evaluate the relationship of concurrent changes in self=reported PA and SB with body composition changes at 12 months using dual-energy X-ray absorptiometry (DEXA).
2. Evaluate the impact of replacing SB with PA at different intensities (LA and MVPA) on BC changes.
Accelerometer-derived inactive time (IT) data was used as a proxy for SB.
Study Design:
The study was nested in the PREDIMED-Plus trial, registered at ISRCTN (89898870). 1564 participants were recruited for the sub-sample (men aged 55-75 n=813; women aged 60-75 n=751) with a BMI >27 and < 40kg/m2 and 3 components of MetS. Data was collected at baseline, 6 and 12 months.
Intervention:
Multicomponent weight loss based on energy restricted Mediterranean Diet (erMedDiet), increasing 30 mins of total PA with behavioural support.
Control:
MedDiet without energy restriction or additional support.
Results:
- At 12 months, participants (intervention and control groups) reduced their waist circumference, BMI, body fat, visceral adipose tissue (VAT) and total energy intake compared to baseline. They increased percentage of muscle mass and muscle-to-fat mass ratio.
- At 6 and 12 months, participants accrued more total PA, LPA and MVPA and less total SB compared to baseline.
After adjustment for potential confounders:
- Increasing 30 min of PA was significantly associated with a decrease in body fat (β − 0.07%, 95% CIs − 0.10; − 0.04%) and VAT (− 13.9 g; − 21.5; − 6.23) and increased muscle mass (0.07%; 0.04; 0.10) and muscle-to-fat mass ratio (0.41; 0.15; 0.67).
- Increasing 30 min of MVPA was linked to significantly reduced body fat (− 0.08%, − 0.11; − 0.04%) and VAT (− 15.6 g; − 24.1; − 7.25) and with increased muscle mass (0.07%; 0.04; 0.10) and muscle-to-fat mass ratio (0.44; 0.15; 0.72).
- Overall, 30 more minutes of total SB was associated with significantly greater body fat and lower muscle mass.
- No significant associations were observed for LPA.
Conclusions:
Increasing PA and substituting SB with PA, in particular MVPA is correlated with improvements in body composition in overweight or obese older adults with MetS.
Clinical practice applications:
- To inform older clients (>55yrs) on the benefits of PA on a range of health conditions e.g. cardiovascular disease and symptoms e.g. metabolic symptoms
- To provide guidance on the benefits of replacing SB with PA, with examples of optimal amount of time and intensity, obviously working within professional boundaries and referring on to relevant experts when necessary
- To encourage practitioners to include recommendations of physical activity as part of a comprehensive approach to physical well-being
Considerations for future research:
- Analyse how increases in physical activity may benefit other chronic health conditions in older adults
- Evaluate how exchanging sedentary behaviour with physical activity may benefit mental health symptoms such as mood and anxiety in adults.
- Explore different facilitators and barriers to increasing physical activity to reduce sedentary behaviour in adults.
Abstract
BACKGROUND The optimal distribution between physical activity (PA) levels and sedentary behaviour (SB) for the greatest benefits for body composition among older adults with overweight/obesity and chronic health conditions remains unclear. We aimed to determine the prospective association between changes in PA and in SB with concurrent changes in body composition and to examine whether reallocating inactive time into different physical activity levels was associated with 12-month change to body composition in older adults. METHODS Longitudinal assessment nested in the PREDIMED-Plus trial. A subsample (n = 1564) of men and women (age 55-75 years) with overweight/obesity and metabolic syndrome from both arms of the PREDIMED-Plus trial was included in the present analysis. Participants were followed up at 6 and 12 months. Physical activity and SB were assessed using validated questionnaires. Out of 1564 participants, 388 wore an accelerometer to objectively measure inactive time and PA over a 7-day period. At each time point, participants' body composition was measured using dual-energy X-ray absorptiometry (DXA). Standard covariate-adjusted and isotemporal substitution modelling were applied to linear mixed-effects models. RESULTS Increasing 30 min of total PA and moderate-to-vigorous physical activity (MVPA) was associated with significant reductions in body fat (β - 0.07% and - 0.08%) and visceral adipose tissue (VAT) (- 13.9 g, and - 15.6 g) at 12 months (all p values < 0.001). Reallocating 30 min of inactive time to MVPA was associated with reductions in body fat and VAT and with an increase in muscle mass and muscle-to-fat mass ratio (all p values < 0.001). CONCLUSIONS At 12 months, increasing total PA and MVPA and reducing total SB and TV-viewing SB were associated with improved body composition in participants with overweight or obesity, and metabolic syndrome. This was also observed when substituting 30 min of inactive time with total PA, LPA and MVPA, with the greatest benefits observed with MVPA. TRIAL REGISTRATION International Standard Randomized Controlled Trial (ISRCTN), 89898870 . Retrospectively registered on 24 July 2014.
