Date of Award

Fall 12-13-2011

Degree Type


Degree Name

Doctor of Philosophy (PhD)


Kinesiology and Health

First Advisor

J. Andrew Doyle, PhD

Second Advisor

Christopher Ingalls, PhD

Third Advisor

Jeffrey Rupp, PhD

Fourth Advisor

Dan Benardot, PhD


This study determined the effect of N-acetylcysteine (NAC) supplementation on recovery of strength following eccentric muscle injury. Female subjects (n = 21, age = 20.7 ± .10 yr, weight = 68.05 ± 10.3 kg, height = 1.69 ± .07 m) performed one bout of eccentric exercise involving the forearm flexor muscles. Subjects were given a placebo (food-grade cellulose; n = 10) or NAC supplement (10 mg·kg-1 bw·d-1; n = 11) for 7D prior to and 14D following the exercise bout. Maximal Voluntary Contraction (MVC) torque, muscle soreness, range of motion (ROM), and arm circumference were measured at pre-exercise, immediately post-exercise, and at 1D, 3D, 7D and 10D post-exercise. In addition, serum interleukin-6 (IL-6), serum creatine kinase (CK), and serum glutathione were measured. Subjects also completed a food frequency questionnaire to determine the antioxidant content of their diet. There was no difference in the loss and subsequent recovery of muscular strength between the placebo and NAC group immediately post-exercise (26.93 ± 6.4 vs. 24.95 ±9.4 Nm), 1D (27.83 ± 5.7 vs. 26.9 ± 8.5 Nm), 3D (38.35 ± 6.7 vs. 34.69 ± 10.2 Nm), 7D (46.9 ± 8.8 vs. 42.5 ± 11.8 Nm), or 10D (57.83 ± 11.7 vs. 52.92 ± 14.3 Nm) post-exercise (p = .274). In addition, there was no difference in muscle soreness (p = .752), arm circumference (p = .535), ROM (p = .539), serum CK (p = .449), serum glutathione (p = .967), or serum IL-6 (p = .360) at any time point. Scores on the food frequency questionnaire demonstrated that dietary antioxidant intake was not different between groups (41.04 ± 8.04 vs. 33.01 ± 12.6; p = .054). In conclusion, a bout of eccentric forearm flexor exercise resulted in muscle injury and a significant decrease in subjects’ ability to produce force. Supplementation with NAC had no effect on recovery of strength, arm circumference, ROM, serum CK, serum IL-6, or serum glutathione at any time point following the exercise bout. These results demonstrate that NAC has no effect on recovery of strength following eccentric muscle injury.

Included in

Kinesiology Commons