The effect of daily protein supplementation, with or without resistance training for 1 year, on muscle size, strength, and function in healthy older adults: A randomized controlled trial.

BACKGROUND: Protein supplementation alone or combined with resistance training has been proposed to be effective in counteracting age-related losses of muscle mass and strength. OBJECTIVES: To investigate the effect of protein supplementation alone or combined with light-intensity or heavy-load resistance exercise on muscle size, strength, and function in older adults. METHODS: In a 1-y randomized controlled trial, 208 healthy older adults (>65 y) were randomly assigned to 1 of 5 interventions: 1) carbohydrate supplementation (CARB); 2) collagen protein supplementation (COLL); 3) whey protein supplementation (WHEY); 4) light-intensity resistance training 3-5 times/wk with whey protein supplementation (LITW); and 5) heavy resistance training 3 times weekly with whey protein supplementation (HRTW). Protein supplements contained 20 g protein + 10 g carbohydrate, whereas CARB contained 30 g of carbohydrates. All intervention groups received the supplement twice daily. The primary outcome was change in the quadriceps cross-sectional area (qCSA). Secondary outcomes included measures of lower extremity strength and power, functional capabilities, and body composition. RESULTS: There were 184 participants who completed the study. COLL and WHEY did not affect any measured parameter compared to CARB. Compared to WHEY, HRTW improved the qCSA size (between-group difference, +1.68 cm2; 95% CI, +0.41 to +2.95 cm2; P = 0.03), as well as dynamic (+18.4 Nm; 95% CI, +10.1 to +26.6 Nm; P < 10-4) and isometric knee extensor strength (+23.9 Nm; 95% CI, +14.2 to +33.6 Nm; P < 10-5). LITW did not improve the qCSA size, but increased dynamic knee extensor strength compared to WHEY (+13.7 Nm; 95% CI, +5.3 and +22.1 Nm; P = 0.01). CONCLUSIONS: Recommending protein supplementation as a stand-alone intervention for healthy older individuals seems ineffective in improving muscle mass and strength. Only HRTW was effective in both preserving muscle mass and increasing strength. Thus, we recommend that future studies investigate strategies to increase long-term compliance to heavy resistance exercise in healthy older adults. This trial was registered at clinicaltrials.gov as NCT02034760.

Physical fitness in community-dwelling older adults is linked to dietary intake, gut microbiota, and metabolomic signatures.

When humans age, changes in body composition arise along with lifestyle-associated disorders influencing fitness and physical decline. Here we provide a comprehensive view of dietary intake, physical activity, gut microbiota (GM), and host metabolome in relation to physical fitness of 207 community-dwelling subjects aged +65 years. Stratification on anthropometric/body composition/physical performance measurements (ABPm) variables identified two phenotypes (high/low-fitness) clearly linked to dietary intake, physical activity, GM, and host metabolome patterns. Strikingly, despite a higher energy intake high-fitness subjects were characterized by leaner bodies and lower fasting proinsulin-C-peptide/blood glucose levels in a mechanism likely driven by higher dietary fiber intake, physical activity and increased abundance of Bifidobacteriales and Clostridiales species in GM and associated metabolites (i.e., enterolactone). These factors explained 50.1% of the individual variation in physical fitness. We propose that targeting dietary strategies for modulation of GM and host metabolome interactions may allow establishing therapeutic approaches to delay and possibly revert comorbidities of aging.

Identifying notions of environment in obesity research using a mixed-methods approach.

The recent rise of computation-based methods in social science has opened new opportunities for exploring qualitative questions through analysis of large amounts of text. This article uses a mixed-methods design that incorporates machine reading, network analysis, semantic analysis, and qualitative analysis of 414 highly cited publications on obesogenic environments between 2001 and 2015. The method produces an elaborate network map exhibiting five distinct notions of environment, all of which are currently active in the field of obesity research. The five notions are institutional, built, food, family, and bodily environments. The network map is proposed as a navigational tool both for policy actors who wish to coordinate efforts between a variety of stakeholders and for researchers who wish to understand their own research and research plans in light of different positions in the field. The final part of the article explores how the network map may also initiate a broader set of reflections on the configuration, differentiation, and coherence of the field of obesity research.

Careful science? Bodywork and care practices in randomised clinical trials.

Concern about obesity has prompted numerous public health campaigns that urge people to be more physically active. The campaigns often include normative statements and attempt to impose restrictions on individuals' lives without considering the complexities of daily life. We suggest that broadening the focus to reflect everyday practices would foster better targeted public health campaigns. This article is based on our participation in FINE, a multidisciplinary Danish research project. The core methodology of FINE was a randomised controlled trial in which 61 moderately overweight men were put into different exercise groups. In this article we analyse the scientific work of the trial as representing entangled processes of bodywork, where data are extracted and objectified bodies are manipulated and care practices address the emotional, social and mundane aspects of the participants' everyday lives. Care practices are an inherent part of producing scientific facts but they are removed from the recognised results of scientific practice and thus from common public health recommendations. However, knowledge about the strategic use of care practices in lifestyle interventions is important for public health initiatives and future efforts should incorporate this aspect.