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 .
Effects of isometric strength training on quadriceps muscle properties in over 55 year olds
Changes in strength , speed and size of the quadriceps muscle have been investigated in elderly men and women after 6 months of isometric strength training . We have also indirectly investigated the role of metabolites as a stimulus for muscle hypertrophy by study ing two training protocol s. One thigh was trained using short , intermittent contractions ( IC ) , while the other trained using long , continuous contractions ( CC ) . This meant that there should be a greater metabolite change in the muscle performing CC , as the blood flow is occluded for longer . Nine subjects [ eight women , mean ( SE ) age , 71.8 ( 2.9 ) years ] were measured for contractile properties and strength before and after training , and compared to nine age-matched controls [ 71.5 ( 2.1 ) years ] . The training group increased quadriceps strength by 48.7 (9.1)% ( P < 0.005 ) and 53.1 ( 11.3 ) % ( P < 0.005 ) following the IC and CC protocol s , respectively . There was no change in muscle strength in the controls . Both muscles showed significant slowing after training as measured by the relaxation times and the force-frequency ratio . There were non-significant decreases in muscle fatigability after training . The control group also showed some significant decreases in fatigability and muscle speed . The training group showed significant increases in muscle ( and bone ) cross-sectional area of 4.0 (1.7)% and 4.9 (1.3)% following the CC and IC protocol s , respectively . These increases were significantly different from the decrease observed in the control group . These findings suggest that people over the age of 55 still have the capacity to increase muscle strength and size , and that the training causes slowing of the muscle . Muscle hypertrophy does not seem to be strongly influenced by metabolite changes in this age group , as there were no differences in measurements observed between protocol
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 .