Assessing the Effects of Dietary Protein Supplementation on Sarcopenia in Community-Dwelling Older Adults

Effectiveness of interventions to prevent or reverse pre-frailty and frailty in middle-aged community dwelling adults: A systematic review

INTRODUCTION

Frailty, marked by diminished physiological capacity and higher health risks, is less understood in middle-aged individuals (40-65 years) than older adults. This review synthesises intervention studies for pre-frailty and frailty in this demographic, assessing effectiveness, feasibility, and implementation factors including participant experience and cost-effectiveness.

METHOD

Registered on the Open Science Framework and adhering to the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) and the template for intervention description and replication (TIDieR) guidelines, this review searched six databases for interventions targeting middle-aged adults. Dual screening, data extraction, risk assessment, and Grading of Recommendations, Assessment, Development, and Evaluations (GRADE) certainty evaluation were conducted. Findings were narratively synthesized due to heterogeneity.

RESULTS

Eight studies (2018-2023) with 2838 participants were included. Resistance training and multicomponent exercise reduced frailty; though, not always significantly. Low-intensity exercises and education-based interventions yielded mixed results, suggesting a need for further research. Positive participant experiences and cost-effectiveness of interventions such as resistance training and educational interventions supports their feasibility. Varying quality, methodologies and levels of bias indicated a need for more rigorous future research.

DISCUSSION

This review reveals an evidence gap in middle-aged frailty interventions. Multicomponent interventions and resistance training showed promise, but their comparative effectiveness remains uncertain. Educational and low-intensity interventions need further research to establish their effectiveness. The findings diverge from those in older adults, emphasising the need for age-specific approaches. Future studies should employ higher-quality methods and explore emerging technologies to enhance intervention effectiveness for pre-frailty and frailty in middle-aged adults.

Mitochondrial involvement in sarcopenia

Sarcopenia lowers the quality-of-life for millions of people across the world, as accelerated loss of skeletal muscle mass and function contributes to both age- and disease-related frailty. Physical activity remains the only proven therapy for sarcopenia to date, but alternatives are much sought after to manage this progressive muscle disorder in individuals who are unable to exercise. Mitochondria have been widely implicated in the etiology of sarcopenia and are increasingly suggested as attractive therapeutic targets to help restore the perturbed balance between protein synthesis and breakdown that underpins skeletal muscle atrophy. Reviewing current literature, we note that mitochondrial bioenergetic changes in sarcopenia are generally interpreted as intrinsic dysfunction that renders muscle cells incapable of making sufficient ATP to fuel protein synthesis. Based on the reported mitochondrial effects of therapeutic interventions, however, we argue that the observed bioenergetic changes may instead reflect an adaptation to pathologically decreased energy expenditure in sarcopenic muscle. Discrimination between these mechanistic possibilities will be crucial for improving the management of sarcopenia.