Conclusions : Age-related differences support the impact of stroke-related sarcopenia as a contributor to hemiparetic muscle dysfunction .
Abstract Background : Despite extensive study of the impact of stroke on muscle and functional performance , questions remain regarding the extent to which changes are due to the neurological injury vs. age-related loss of morphology and force production .
Objectives : To synthesize available evidence describing post-stroke changes in lower extremity muscle size and strength compared to healthy adults .
Attenuation of skeletal muscle and strength in the elderly: The Health ABC Study.
Although loss of muscle mass is considered a cause of diminished muscle strength with aging , little is known regarding whether composition of aging muscle affects strength . The skeletal muscle attenuation coefficient , as determined by computed tomography , is a noninvasive measure of muscle density , and lower values reflect increased muscle lipid content . This investigation examined the hypothesis that lower values for muscle attenuation are associated with lower voluntary isokinetic knee extensor strength at 60 degrees/s in 2,627 men and women aged 70 - 79 yr participating in baseline studies of the Health ABC Study , a longitudinal study of health , aging , and body composition .  Strength was higher in men than in women ( 132.3 + /- 34.5 vs. 81.4 + /- 22.0 N x m , P < 0.01 ) . Men had greater muscle attenuation values ( 37.3 + /- 6.5 vs. 34.7 + /- 7.0 Hounsfield units ) and muscle cross-sectional area ( CSA ) at the midthigh than women ( 132.7 + /- 22.4 vs. 93.3 + /- 17.5 cm(2 ) , P < 0.01 for both ) . The strength per muscle CSA ( specific force ) was also higher in men ( 1.00 + /- 0.21 vs. 0.88 + /- 0.21 N x m x cm(-2 ) ) . The attenuation coefficient was significantly lower for hamstrings than for quadriceps ( 28.7 + /- 8.7 vs. 41.1 + /- 6.9 Hounsfield units , P < 0.01 ) . Midthigh muscle attenuation values were lowest ( P < 0.01 ) in the eldest men and women and were negatively associated with total body fat ( r = -0.53 , P < 0.01 ) . Higher muscle attenuation values were also associated with greater specific force production ( r = 0.26 , P < 0.01 ) . Multivariate regression analysis revealed that the attenuation coefficient of muscle was independently associated with muscle strength after adjustment for muscle CSA and midthigh adipose tissue in men and women . These results demonstrate that the attenuation values of muscle on computed tomography in older persons can account for differences in muscle strength not attributed to muscle quantity
Conclusions : Age-related differences support the impact of stroke-related sarcopenia as a contributor to hemiparetic muscle dysfunction .
Abstract Background : Despite extensive study of the impact of stroke on muscle and functional performance , questions remain regarding the extent to which changes are due to the neurological injury vs. age-related loss of morphology and force production .
Objectives : To synthesize available evidence describing post-stroke changes in lower extremity muscle size and strength compared to healthy adults .