Effects of Repeated Bouts of Long-duration Endurance Exercise on Muscle and Urinary Levels of 8-hydroxy-2’-deoxyguanosine in Moderately Trained Cyclists

摘要

The purpose of this study was to determine the effects of repeated bouts of long-duration endurance exercise on both muscle and urinary levels of oxidative DNA damage in moderately trained individuals. Seven moderately trained male cyclists participated in this study. All participants repeated two sessions consisting of a 5 hour cycling period (equivalent to approximately 52% VO2peak) followed by a 15 hour rest, then a 40 km time trial. During the sessions, participants were instructed to take water ad libitum and to consume a standard sports drink consisting of 0.12 g·kg⁻¹ body weight·hr⁻¹ of carbohydrates. For each session, 24 hour urine output was collected on the day before the 5 hour exercise, and also between the 5 hour exercise and 40 km time trial, in addition to between days 1–5 post-exercise. Subsequently, muscle and urinary levels of 8-hydroxy-2’- deoxyguanosine (8-OHdG) were determined using high performance liquid chromatography with electrochemical detection. No significant alterations were observed between two sessions at the muscle or urinary levels of 8-OHdG. These results suggest that repeated bouts of exercise with a 7 day wash-out period did not lead to an accumulation of DNA damage products after a second 5 hour stationary cycling bout.