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 .
Knee extension strength and walking speed in relation to quadriceps muscle composition and training in elderly women.
Knee extension strength , walking speed , quadriceps muscle mass and composition of the muscle compartment were studied in 66 to 85-year-old female athletes and controls .  Maximal voluntary knee extension force , force/body mass , extension torque , torque/body mass and walking speed were higher for the athletes than the controls . A muscle index indicating intramuscular fat and connective tissue measured using ultrasonography was lower for the athletes than the controls . There were no differences between the study groups in knee extension force related either to cross-sectional area ( CSA ) or lean tissue area ( CSAL ) of the quadriceps . Within the subgroups , there was no significant correlation between knee extension torque and CSA or CSAL of the same muscle . In the athletes high knee extension torque/body mass was related to a low muscle index and high walking speed to a low relative proportion of fat in the muscle . The muscle index was lower the more kilometers trained during the preceding year . In the controls high knee extension torque/body mass and high walking speed were related to a low relative proportion of fat . Knee extension torque and walking speed were higher the more kilometers walked during the preceding year . The results indicate that elderly female athletes have superior muscle performance compared to their age-peers . Performance in a maximal isometric strength test in elderly women is not clearly related to muscle mass . However , to some extent it is related to the composition of the same muscle , especially the degree to which fat is infiltrated into the muscle
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 .