The Impact of Intensity on Exercise-Induced Oxidative Stress in Trained Men

Exercise has been noted in some, but not all studies, to elicit an oxidative stress response. The discrepancy in findings may be related to differences in exercise intensity across study protocols. Biomarkers of oxidative stress were compared for aerobic and anaerobic exercise bouts of different intensities and durations. On different days, exercised-trained men (n=12; 21-35 yrs) performed aerobic cycle exercise (60 min at 70% HR reserve) and anaerobic cycle sprints (five, 60 sec sprints at 100% max GXT watts; and ten, 15 sec sprints at 200% max GXT watts). Blood was collected before and 0, 30, and 60 min post-exercise and analyzed for malondialdehyde (MDA), hydrogen peroxide (H2O2), and Trolox Equivalent Antioxidant Capacity (TEAC). No differences were noted in MDA or H2O2. TEAC was significantly higher at 30 and 60 min post-exercise. In exercise-trained men, no increase was noted in post-exercise oxidative stress, possibly due to the increase in antioxidant defense

Relationship Between Metabolic By-Products and Nervous System Failure/Fatigue

Fatigue has generally been defined as an acute impairment of exercise/sport performance that includes both an increase in the perceived effort necessary to exert a desired force or power output, and the inability to produce the desired force or power output. The majority of research to date looking at fatigue has focused upon substrate utilization, however, what is relatively unknown is the contribution the nervous system has upon fatigue. Therefore, the purpose of this dissertation was to investigate potential mechanisms that relate to neural fatigue. An additional purpose was to determine if there were any relationships between metabolic by-products and EMG characteristics following exercise. The first investigation sought to determine changes in EMG M-wave amplitude of the gastrocnemius following the calf raise exercise. There were no significant changes in M-wave EMG amplitude following exercise. The second investigation compared changes in muscle contractile properties and EMG characteristics of the VL, RF, and VM following a high-intensity exercise. There was a significant decrease in MDF of the VL only. Additionally, there was a decrease in peak force and rate of force development. The last investigation utilized the same exercise protocol as the second investigation, but added the supplementation of aspartate and sodium bicarbonate. Both supplements were effective in reducing ammonia concentrations following exercise. Additionally, supplementation with sodium bicarbonate resulted in an increase in rate of force development following exercise. As for EMG characteristics, there was a significant decrease in MDF for the RF, but not the VL. There were no significant changes in PF or EMG amplitude. Currently, no relationship between the metabolic and nervous systems during times of fatigue can be determined at this point