Atrophy and intramuscular fat in specific muscles of the thigh: associated weakness and hyperinsulinemia in stroke survivors.

PURPOSE: Sarcopenia and increased fat infiltration in muscle may play a role in the functional impairment and high risk for diabetes in stroke. Our purpose was to compare muscle volume and muscle attenuation across 6 muscles of the paretic and nonparetic thigh and examine the relationships between intramuscular fat and insulin resistance and between muscle volume and strength in stroke patients.
METHODS: Stroke participants (70; 39 men, 31 women) aged 40 to 84 years, BMI = 16 to 45 kg/m(2) underwent multiple thigh CT scans, total body scan by DXA (dual-energy X-ray absorptiometry), peak oxygen intake (VO(2peak)) graded treadmill test, 6-minute walk, fasting blood draws, and isokinetic strength testing.
RESULTS: Muscle volume is 24% lower and subcutaneous fat volume is 5% higher in the paretic versus nonparetic thigh. Muscle attenuation (index of amount of fat infiltration in muscle) is 17% higher in the nonparetic midthigh than the paretic. The semitendinosis/semimembranosis, biceps femoris, sartorius, vastus (medialis/lateralis), and rectus femoris have lower (between 9% and 19%) muscle areas on the paretic than the nonparetic thigh. Muscle attenuation is 15% to 25% higher on the nonparetic than the paretic side for 5 of 6 muscles. The nonparetic midthigh muscle attenuation is negatively associated with insulin. Eccentric peak torque of the nonparetic leg and paretic leg are associated with the corresponding muscle volume.
CONCLUSIONS: The skeletal muscle atrophy, increased fat around and within muscle, and ensuing muscular weakness observed in chronic stroke patients relates to diabetes risk and may impair functional mobility and independence.