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Huber, G.

Journal of Geriatric Physical Therapy: December 2005 - Volume 28 - Issue 3 - p 113

Department of Physical Therapy and Human Movement Sciences, Northwestern University, Chicago, IL.

Purpose/Hypothesis: Models of disablement progress from systemic changes to alteration of function and the ability to take an active role in society. It is important to understand if resistance training influences the components of disablement in systematic ways. The purpose of this study is to examine the evidence for the effects of resistance training on proximal domains of the disablement model. The proximal domains are pathology and impairment. Frequently reported outcomes for resistance training classified under the proximal domains are increased muscle size(pathology domain) and increased strength (impairment domain). Number of Subjects: This meta-analysis examined the effects of resistance training in adults > 60 years of age. Studies published in English from 1980-2001 were reviewed and 61 randomized-control studies and 42 non-randomized studies were analyzed. Materials/Methods: Meta-anlaysis is a quantitative method of synthesizing research. The standardized d-statistic was used for analysis in both fixed and random effects models. Muscle size outcomes were crosssectional area and Type I and Type II muscle fibers. Strength outcomes were analyzed for ankle dorsiflexion, knee extension, hip abduction, bench press, leg press and power. Meta-regression was used to analyze the effects of moderators. Moderators were based on subject characteristics (age, gender, disease state), program characteristics (exercise dose, length, setting), and study characteristics (publication year and quality). Results: The number of effect sizes (ES) varied by domain for both randomized and non-randomized studies as follows: pathology-9/1 and impairment-53/36;. Significant effect sizes were found for outcomes in both domains. Moderate-large (0.5-.79) effect sizes were found for muscle size (Type II fiber area, d=0.71)-and strength (muscle groups ranged d=.54-.78) in the randomized studies. ES were larger in the non-randomized studies. No consistent pattern of result was identified by the moderator analysis however, resistance training programs for pathology were generally of higher intensity and volume than for the impairment outcomes. Conclusions: This study demonstrates the importance of resistance training in improving outcomes for the proximal domains of disablement. Non-randomized studies provide additional information for some underreported outcomes. Moderator analysis demonstrates that the majority of older adults will benefit from resistance training. Improved reporting of training dose in the published literature is needed for analysis of the necessary dose of exercise for each domain. Clinical Relevance: There is evidence that resistance training of adequate dose will effect muscle size and strength in varied populations of adults > 60 years of age and should be incorporated in regular physical activity.

© 2005 Lippincott Williams & Wilkins, Inc.