PRT had a large positive effect on strength ( 41 trials , 1955 participants ) , but there was statistical heterogeneity that was not explained by differences in study quality , participant characteristics or the exercise program .
REVIEW ER 'S CONCLUSIONS PRT appears to be an effective intervention to increase strength in older people and has a positive effect on some functional limitations .
However , the effect of this intervention on more substantive outcomes such as measures of disability or HRQOL remains unclear .
BACKGROUND Muscle weakness in old age , is associated with physical disability and an increased risk of falls .
Progressive resistance strength ( PRT ) training exercises ( i.e. movements performed against a specific external force that is regularly increased during training ) are design ed to increase strength in older people .
OBJECTIVES To assess the effect of PRT on measures of physical disability , functional limitation and impairment in older people  , and identify adverse events .
Growth hormone administration and exercise effects on muscle fiber type and diameter in moderately frail older people.
OBJECTIVE Reduced muscle mass and strength are characteristic findings of growth hormone deficiency ( GHD ) and aging . We evaluated measures of muscle strength , muscle fiber type , and cross sectional area in response to treatment with recombinant human growth hormone ( rhGH ) with or without a structured resistance exercise program in frail older subjects . DESIGN Placebo-controlled , r and omized , double blind trial . SETTING Outpatient clinical research center at an urban university-affiliated teaching hospital . PARTICIPANTS Thirty-one consenting older subjects ( mean age 71.3 + /- 4.5 years ) recruited as a subset of a larger project evaluating rhGH and exercise in older people , who underwent 62 quadricep-muscle biopsies . INTERVENTION R and om assignment to a 6-month course of one of four protocol s : rhGH administered subcutaneously daily at bedtime , rhGH and a structured resistance exercise program , structured resistance exercise with placebo injections , or placebo injections only . MEASUREMENTS Muscle biopsy specimens were obtained from the vastus lateralis muscle . Isokinetic dynamometry strength tests were used to monitor individual progress and to adjust the weights used in the exercise program . Serum insulin-like growth factor-I ( IGF-I ) was measured and body composition was measured using a Hologic QDR 1000W dual X-ray densitometer . RESULTS The administration of rhGH result ed in significant increase in circulating IGF-I levels in the individuals receiving rhGH treatment . Muscle strength increased significantly in both the rhGH/exercise ( + 55.6 % , P = .0004 ) as well as the exercise alone ( + 47.8 % , P = .0005 ) groups . There was a significant increase in the proportion of type 2 fibers between baseline and six months in the combined rhGH treated subjects versus those not receiving rhGH ( P = .027 ) . CONCLUSIONS Our results are encouraging in that they suggest an effect of growth hormone on a specific aging-correlated deficit . IGF-I was increased by administrating rhGH and muscle strength was increased by exercise . The administration of rhGH to frail older individuals in this study result ed in significant changes in the proportions of fiber types . Whether changes in fiber cross-sectional area or absolute number occur with long-term growth hormone administration requires further study
PRT had a large positive effect on strength ( 41 trials , 1955 participants ) , but there was statistical heterogeneity that was not explained by differences in study quality , participant characteristics or the exercise program .
REVIEW ER 'S CONCLUSIONS PRT appears to be an effective intervention to increase strength in older people and has a positive effect on some functional limitations .
However , the effect of this intervention on more substantive outcomes such as measures of disability or HRQOL remains unclear .
BACKGROUND Muscle weakness in old age , is associated with physical disability and an increased risk of falls .
Progressive resistance strength ( PRT ) training exercises ( i.e. movements performed against a specific external force that is regularly increased during training ) are design ed to increase strength in older people .
OBJECTIVES To assess the effect of PRT on measures of physical disability , functional limitation and impairment in older people  , and identify adverse events .