Research Review By Lyndsay Foisey ©

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Date Posted:

August 2011

Study Title:

Influence of Resistance Exercise on Lean Body Mass in Aging Adults : A Meta-Analysis

Authors:

Peterson MD, Sen A & Gordon PM

Author's Affiliations:

Department of Physical Medicine and Rehabilitation, Department of Statistics at the University of Michigan, USA.

Publication Information:

Medicine & Science in Sports & Exercise 2011; 43(2): 249-258.

Background Information:

Sarcopenia is defined as muscle atrophy associated with aging. It can cause major functional decline in older adults, along with a loss of autonomy, quality of life and as a result inflate subsequent health care costs. Resistance exercise (RE) is recommended to slow and/or prevent sarcopenia. However, there exists much variability in the literature regarding the dose-response relationship for RE and the efficacy of different training programs. In addition, many studies include lean body mass as only a secondary outcome. The present study is one of the first to analyze lean body mass as a primary outcome across multiple RE training programs and age cohorts.

Pertinent Results:

  • RE increased lean body mass in older adults by an average of 1.1kg in a variety of studies
  • Not surprisingly, greater training volume resulted in superior gains of lean body mass compared to lower training volume programs; however, other training variables such as intensity and frequency were not found to be statistically significant in their influence on lean body mass
  • Compared to younger age cohorts, older adults did not gain as much lean body mass. Therefore, for optimal results, older adults should begin RE as early as possible
  • On average, the programs consisted of exercising two to three times per week (mean = 2.8, SD = 0.4), at an average intensity of 74.6% (SD = 6.9%) of 1RM. The number of exercises on average was 8.3 (SD = 2.1), for an average total of 20 sets per total body program (SD = 7.3) at ten repetitions, and a rest between sets of 110s. The majority of the studies corresponded with the guidelines of RE for older adults recommended by the American College of Sports Medicine.

Clinical Application & Conclusions:

  • As older adults can reportedly lose an average of 0.18kg of lean body mass per year after the age of 50, it is recommended for this population to begin a RE program as soon as possible to maximize muscle gain and minimize muscle loss
  • A higher training volume appears to be better for adaptive purposes
  • Most of the studies examined found that RE programs simply increased the amount of load lifted over the trial period; however, younger age cohorts followed a periodization model of progression in intensity, volume and more. Therefore, single set/fixed volume RE programs may not be sufficient for older adults who desire increases in lean body mass, and RE programs for older adults should include a systematic progression of training volume

Study Methods:

Trials with the following criteria were reviewed and analyzed:
  • 49 studies from 1990 to 2009 (37% were randomized controlled trials, and the remaining were non-randomized controlled trials)
  • Studies were accepted if subjects were at least 50 years old and untrained. Of the 1328 subjects from the selected studies, the mean age was 65.5 years (SD = 6.5 yrs)
  • Length of trials ranged from 10 to 52 weeks (mean = 20.5 weeks, SD = 9.1)
  • Statistical tests for publication bias (Begg’s funnel plot and Egger’s tests) and heterogeneity (Cochrane’s Q and I²; used to quantify variability between trials) were performed. In addition, a forest plot for main effect, 95% confidence interval and meta-regression were calculated.

Study Strengths / Weaknesses:

Overall, this was a rigorous meta-analysis that provides valuable information regarding factors of RE prescription for healthy older adults. That being said, it did not find statistical significance regarding the other program prescription principles, such as intensity or frequency of training. Future studies are required regarding those training variables. It would be interesting to see if increases in RE volume would apply to special populations, such as older adults residing in long-term care facilities as this population suffers greatly from functional declines.

Nevertheless, this study indicates that current RE prescription guidelines for older adults may be too cautious. Perhaps the current RE guidelines for older adults need to be revisited in order to increase the effectiveness of a program, as well as the much sought after health benefits.

Additional References:

  1. Huber G. The effect of resistance training on disablement outcomes: a meta-analysis [dissertation]. Chicago, IL: University of Illinois; 2005. P. 124.
  2. Moher D, Liberati A, Tetzlaff J, Altman DG, Group P. Preferred reporting items for systematic reviews and meta-analyses: the PRISMA statement. PLoS Med. 2009; 6;e1000097.
  3. American College of Sports Medicine. ACSM’s Resource Manual for Guidelines for Exercise Testing and Prescription: 6th edition. Philadelphia, PA: Lippincott Williams & Wilkins; 2010.