Evaluation of skeletal muscle during calf exercise by 31‐phosphorus magnetic resonance spectroscopy in patients on statin medications

Muscle pain is a common side effect of statin medications, but the cause is poorly understood. We characterized phosphocreatine (PCr) exercise recovery kinetics in 10 patients with hypercholesterolemia before and after a 4‐week regimen of statin therapy using 31‐phosphorus magnetic resonance spectroscopy ( 31 P‐MRS). 31 P spectra were obtained before, during, and after exercise on a calf flexion pedal ergometer. Creatine kinase (CK) serum levels were drawn before and after statin therapy. The mean metabolic recovery time constant in subjects increased from 28.1 s (SE = 6.5 s) to 55.4 s (SE = 7.4 s) after statin therapy. The unweighted mean of the pre/post‐recovery time difference was −27.3 s (SE = 12.4 s; P = 0.02). Pre‐ and post‐therapy CK levels were not significantly different ( P = 0.50). Metabolic recovery time in the calf is prolonged in patients after statin use. This suggests that statins impair mitochondrial oxidative function, and 31 P MRS is a potential study model for statin‐associated myopathy. Muscle Nerve, 2011