University of Oregon

Department of Human Physiology Graduate Studies in Athletic Training and Sports Medicine

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Prostaglandin E2 Production Associated with Exercise-induced Muscle Damage

Eric Sorenson MS ATC

Symptoms of exercise-induced muscle damage (EMD) include soreness and stiffness appearing 24-48 hours after exercise, referred to as delayed onset muscle soreness (DOMS), a prolonged reduction in muscle strength and range of motion, an increase in arm circumference, and the appearance of muscle proteins in the blood (5,10,17). Previous research indicates that prostaglandin E2 (PGE2) may be the most likely chemical stimulant associated with increased sensitivity of pain receptors leading to DOMS (22). The first specific aim of this study was to confirm the presence of EMD following a specific eccentric exercise protocol. The second specific aim was to measure the change in PGE2 following the onset of muscle damage.

Using a motor driven isokinetic dynamometer (Chattecx KinCom) subjects (n=5) performed 2 sets of 35-repetitions of eccentric, isokinetic elbow flexion at 30°/sec. Pain, isometric strength of the elbow flexors, arm circumference, and relaxed arm angle were measured immediately prior to, immediately after, and at 24-, 48-, 72- and 168-hours (7-d) post-exercise. Twenty-four hour urine samples were collected immediately before, and at 24-hour intervals for three days following the exercise protocol. Urine samples were tested for the average levels of PGE2 within each 24-hour collection period. Results: Following eccentric exercise, significant increases were observed in pain and arm circumference, and significant decreases were observed in strength. Statistical analysis showed no change in PGE2 following eccentric exercise.

These data indicate that PGE2 does not increase following a specific eccentric exercise protocol. Further research should include a larger sample size with subjects stratified based upon baseline measures of PGE2 to elaborate on the trends found in this study.