Age-related variations of serum CK and CK MB response in females

The objective was to determine whether serum creatine kinase (CK) and serum CK MB activity following exercise-induced muscle damage activity differs among females of varying menarchial status and to determine whether there is a relationship between serum estradiol (E2) concentration, CK, and CK MB activity. Fifteen menarchial (M), 15 premenarchial (P), and 10 postmenopausal (PM) females participated in the study. Exercise consisted of eccentric hamstring contractions. Estradiol concentrations were significantly higher in M women (p = .0001; M 125.0 +/- 20.8 pg/mL, P, 54.6 +/- 38.6 pg/mL, PM, 46.2 +/- 34.6 pg/mL). Menarchial women had lower resting CK and CK MB activity and responded with a higher efflux of CK and CK MB post exercise (p = .0001). An inverse relationship was found between E2 concentration and baseline CK (p = .02) and CKMB activity (p = .006). No relationship existed between post exercise efflux of CK and CK MB and E2 concentration. At rest, E2 influenced CK and CK MB activity across menarchial levels. However E2 did not significantly reduce the level of CK and CK MB activity following this intense bout of eccentric exercise.