PRT results in improvements to muscle strength and some aspects of functional limitation , such as gait speed , in older adults .
However , based on current data , the effect of PRT on physical disability remains unclear .
Further , due to the poor reporting of adverse events in trials , it is difficult to evaluate the risks associated with PRT
BACKGROUND The aim of this systematic review was to quantify the effectiveness of progressive resistance strength training ( PRT ) to reduce  physical disability in older people .
Dynamic muscle strength alterations to detraining and retraining in elderly men.
To investigate the effects of cessation and subsequent resumption of training on muscle strength in elderly men , 11 men ( aged 65 - 77 years ) , just completing a 24-week r and omized controlled trial of recombinant human growth hormone ( rhGH ) and resistance exercise ( rhGH  , n = 6 ; placebo , n = 5 ) , detrained for 12 weeks and subsequently retrained for 8 weeks . During the detraining and retraining phase , subjects did not receive rhGH . The resistance programme included three sets of eight repetitions at 75 % of one-repetition maximum ( 1-RM ) , three times per week , for 10 upper and lower body exercises .  Dynamic muscle strength was assessed by the 1-RM method every 2 weeks for 44 weeks . Needle biopsies of vastus lateralis muscle were obtained from seven men . Muscle strength increased during initial training by 40.4 + /- 5.5 % ( mean + /- SEM ) , ranging from 26.0 + /- 5.0 to 83.9 + /- 15.6 % , depending on muscle group . Increased strength was accompanied by hypertrophy ( P < 0.05 ) of type I ( 17.4 + /- 4.1 % ) and II ( 25.8 + /- 12.4 % ) muscle fibres . Of initial strength gains , only 29.9 + /- 5.2 % was lost with detraining . However , type I and II fibre cross-sectional area reverted to pretraining values . After 8 weeks of retraining , muscle strength returned to trained values , but without a significant change in fibre morphology . The results indicate that elderly men lose some muscle strength following short-term detraining , but that only a brief period of retraining suffices to regain maximal strength . Reversal of fibre cross-sectional area with detraining , and only modest improvement with retraining , suggests that much of the retention in strength with detraining and reacquisition of lost strength with retraining reflects neural adaptation
PRT results in improvements to muscle strength and some aspects of functional limitation , such as gait speed , in older adults .
However , based on current data , the effect of PRT on physical disability remains unclear .
Further , due to the poor reporting of adverse events in trials , it is difficult to evaluate the risks associated with PRT
BACKGROUND The aim of this systematic review was to quantify the effectiveness of progressive resistance strength training ( PRT ) to reduce  physical disability in older people .