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 .
Age effect on transcript levels and synthesis rate of muscle MHC and response to resistance exercise.
Experimental evidence indicates that a lower synthesis rate of muscle contractile protein myosin heavy chain ( MHC ) occurs in age-related muscle wasting and weakness . To determine the molecular mechanism of this lower synthesis of MHC , we measured transcript levels of isoforms of MHC ( MHCI , MHCIIa , and MHCIIx ) in muscle biopsy sample s of 7 young ( 20 - 27 yr ) , 12 middle-aged ( 47 - 60 yr ) , and 14 older ( > 65 yr ) people . We further determined the effect of 3 mo of resistance exercise training ( exercise ) vs. nonintervention ( control ) on transcript levels of MHC isoforms on these subjects and the fractional synthesis rate ( FSR ) of MHC in 39 people aged 46 - 79 yr .  MHCI mRNA levels did not significantly change with age , but MHCIIa decreased 38 % ( P < 0.05 ) from young to middle age and further decreased 50 % ( P < 0.05 ) from middle to old age . MHCIIx decreased 84 % ( P < 0.05 ) from young to middle age and 48 % from middle to old age ( P < 0.05 ) . Exercise increased FSR of MHC by 47 % ( P < 0.01 ) and mixed muscle protein by 56 % ( P < 0.05 ) . Exercise training results in an increase ( 85 % ) in transcript levels of MHCI and a decrease in the transcript levels of MHCIIa and MHCIIx . In conclusion , an age-related lowering of the transcript levels of MHCIIa and MHCIIx is not reversed by exercise , whereas exercise results in a higher synthesis rate of MHC in association with an increase in MHCI isoform transcript levels
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 .