THE EFFECT OF TRAINING STATUS ON THE SERUM CREATINE-KINASE RESPONSE, SORENESS AND MUSCLE FUNCTION FOLLOWING RESISTANCE EXERCISE

Untrained individuals develop muscle soreness and increased serum crea tine kinase (CK) activity in the blood after strenuous, unaccustomed e xercise. An unpublished observation in our laboratory revealed that tr ained weightlifters also experience considerable soreness after unaccu stomed exercise, but may not show a dramatic CK response. This study e xamined the CK and soreness responses to strenuous exercise in weightl ifters (TR, n=10) and untrained subjects (UTR, n=10). Trained subjects had a minimum of three years weightlifting experience, and regularly performed squats and leg presses. Untrained subjects had not participa ted in any regular resistance exercise for the past three years. Follo wing two acclimation sessions, subjects reported to the lab on seven c onsecutive days and on the tenth day after knee extensor exercise. Wei ght training sessions occurred on day 1 for the knee extensors (KE) an d day 2 for the knee flexors (KF). The weight training consisted of th ese exercises (sets): squat (5), leg press (3), leg extension and lung e (3) for the KE, double leg curls (6), single leg curls (3), stiff-le gged deadlifts (4, TR group only) for the KF at 12 RM for all exercise s. To document the stress due to exercise, the loss in strength (isome tric peak torque, IPT) was assessed on a Biodex isokinetic dynamometer . Maximal voluntary IPT of the KE at 90 degrees and the KF at 80 degre es decreased 17-30% with no significant differences between groups. Mu scle soreness during simulated squat leg curl movement was assessed by a 100 mm visual analog scale (VAS). Average peak KE soreness was 76 m m for TR and 58 mm for UTR, KF soreness was 60 mm for TR and 47 mm for UTR post-exercise. Serum CK levels were significantly different betwe en groups with a peak of 1349 IU for TR and 3272 IU for the UTR (p<0.0 1). Although the TR group experienced greater soreness than the UTR, p eak serum CK activity was significantly lower, suggesting that trained individuals can develop severe soreness without the same degree of in crease in serum CK activity observed in untrained individuals.