title: Influence of resistance exercise on lean body mass in aging adults: a meta-analysis.
abstract: OBJECTIVE
  sarcopenia plays a principal role in the pathogenesis of frailty and functional impairment that occur with aging. There are few published accounts that examine the overall benefit of resistance exercise (RE) for lean body mass (LBM) while considering a continuum of dosage schemes and/or age ranges. Therefore, the purpose of this meta-analysis was to determine the effects of RE on LBM in older men and women while taking these factors into consideration.
  
  
  METHODS
  this study followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses recommendations. Randomized controlled trials and randomized or nonrandomized studies among adults ≥ 50 yr were included. Heterogeneity between studies was assessed using the Cochran Q and the I statistics, and publication bias was evaluated through physical inspection of funnel plots as well as formal rank-correlation statistics. Mixed-effects meta-regression was incorporated to assess the relationship between RE dosage and changes in LBM.
  
  
  RESULTS
  data from 49 studies, representing a total of 1328 participants, were pooled using random-effect models. Results demonstrated a positive effect for LBM, and there was no evidence of publication bias. The Cochran Q statistic for heterogeneity was 497.8, which was significant (P < 0.01). Likewise, I was equal to 84%, representing rejection of the null hypothesis of homogeneity. The weighted pooled estimate of mean LBM change was 1.1 kg (95% confidence interval = 0.9-1.2 kg). Meta-regression revealed that higher-volume interventions were associated (β = 0.05, P < 0.01) with significantly greater increases in LBM, whereas older individuals experienced less increase (β = -0.03, P = 0.01).
  
  
  CONCLUSIONS
  RE is effective for eliciting gains in LBM among aging adults, particularly with higher-volume programs. Findings suggest that RE participation earlier in life may provide superior effectiveness.
authors.affiliation: Laboratory for Physical Activity and Exercise Intervention Research, Department of Physical Medicine and Rehabilitation, University of Michigan, Ann Arbor, MI 48108, USA. mdpeterz@med.umich.edu
authors.forename: Mark D
authors.initials: MD
authors.lastname: Peterson
authors.forename: Ananda
authors.initials: A
authors.lastname: Sen
authors.forename: Paul M
authors.initials: PM
authors.lastname: Gordon
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001823:Body Composition / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D053580:Muscle Strength / Q000502:physiology; D018482:Muscle, Skeletal / Q000502:physiology; D016032:Randomized Controlled Trials as Topic; D055070:Resistance Training