Leucine partially protects muscle mass and function during bed rest in middle-aged adults

Abstract

Bed rest has a profoundly negative effect on muscle metabolism, mass, and function in middle-aged adults. Leucine supplementation may partially protect muscle health during relatively brief periods of physical inactivity. This trial was registered at clinicaltrials.gov as NCT00968344.

Identifying effective and feasible interventions to accelerate functional recovery from hospitalization in older adults: A randomized controlled pilot trial

“…These studies highlight the potential for protein supplements to improve physical functioning in community dwelling frail older adults. Recent data also indicate that the benefits of protein/amino acid supplementation on skeletal muscle health can be achieved during a 2–3 week time frame in clinical populations[77] or models of clinical settings[49]. However, it is still unclear whether nutritional supplementation can also accelerate the functional recovery of older adults following acute hospitalization.…”

“…Due to the paucity of comparable studies, we have selected a reasonable sample size for a pilot/feasibility study of 20/group and calculated power using the estimated change and standard deviations reported in post bed rest rehabilitation studies in healthy older adults and the existing literature on hospitalized geriatric patients [43, 48, 49]. The outcomes for calculating power are presented in Table 2.…”

Variation in Protein Origin and Utilization: Research and Clinical Application

“…Similarly, in a cohort of middle‐aged adults, 3–4 g leucine added to each meal partially protected lean leg mass but only during the first week of a 14‐day bedrest study. The time‐sensitive protective effect was facilitated by the partial preservation of muscle protein synthesis and accompanied by the partial conservation of muscular strength, endurance, and aerobic capacity 41 …”

“…The time-sensitive protective effect was facilitated by the partial preservation of muscle protein synthesis and accompanied by the partial conservation of muscular strength, endurance, and aerobic capacity. 41 While data from bedrest and acute research studies are encouraging, leucine supplementation is not unconditionally effective, and there is a lack of information on its use in clinical populations or via enteral or parenteral administration routes. Specifically, supplemental leucine may be of limited benefit for active individuals habitually consuming a protein/leucine-sufficient diet (ie, >1.0 g/kg body weight/d).…”

“…In bedrest studies with healthy volunteers, as little as 3-4 days of inactivity can impair whole-body glucose tolerance. 41,75 In a patient population who may already be insulin resistant, if not type 2 diabetic, the consequence of ingesting a high proportion of simple carbohydrate, in combination with low protein, is metabolically detrimental and likely compromises the overarching goal of protecting muscle health while addressing the root medical problem. 57 Several recent studies have examined the anabolic dose response to the bolus ingestion of protein.…”