Inflammatory, Oxidative Stress, and Angiogenic Growth Factor Responses to Repeated-Sprint Exercise in Hypoxia.

The present study was designed to determine the effects of repeated-sprint exercise in moderate hypoxia on inflammatory, muscle damage, oxidative stress, and angiogenic growth factor responses among athletes. Ten male college track and field sprinters [mean ± standard error (SE): age, 20.9 ± 0.1 years; height, 175.7 ± 1.9 cm; body weight, 67.3 ± 2.0 kg] performed two exercise trials in either hypoxia [HYPO; fraction of inspired oxygen (FiO2), 14.5%] or normoxia (NOR; FiO2, 20.9%). The exercise consisted of three sets of 5 s × 6 s maximal sprints with 30 s rest periods between sprints and 10 min rest periods between sets. After completing the exercise, subjects remained in the chamber for 3 h under the prescribed oxygen concentration (hypoxia or normoxia). The average power output during exercise did not differ significantly between trials (p = 0.17). Blood lactate concentrations after exercise were significantly higher in the HYPO trial than in the NOR trial (p < 0.05). Plasma interleukin-6 concentrations increased significantly after exercise (p < 0.01), but there was no significant difference between the two trials (p = 0.07). Post-exercise plasma interleukin-1 receptor antagonist, serum myoglobin, serum lipid peroxidation, plasma vascular endothelial growth factor (VEGF), and urine 8-hydroxydeoxyguanosine concentrations did not differ significantly between the two trials (p > 0.05). In conclusion, exercise-induced inflammatory, muscle damage, oxidative stress, and VEGF responses following repeated-sprint exercise were not different between hypoxia and normoxia.

Impact of inserted long rest periods during repeated sprint exercise on performance adaptation.

Repeated sprint training consists of a series of brief maximal sprints, 3-7 s in duration, separated by short rest periods of <60 s. However, little is known about the influence of different rest period lengths between sprints on performance adaptation. We determined the influence of inserting long rest periods during repeated sprint training on performance adaptation in competitive athletes. Twenty-one well-trained athletes were separated into either the short rest period group (SHORT; n = 10) or the long rest period group (LONG; n = 11). The training protocol for both groups consisted of two sets of 12 × 6-s maximal cycle sprints with 24 s of rest between sprints. However, in the LONG group, an active rest period of 7 min was inserted every three sprints to attenuate the power output decrement during the latter half of the sprints. The training was performed 3 d/week for 3 weeks. Before and after the training period, repeated sprint ability [12 × 6-s maximal sprint (pedaling) with 24-s rest] was evaluated. Maximal power output during the repeated sprint test was significantly increased only in the LONG group (P < .05). Both groups showed a similar increase in power output during the latter half of sprints (P < .05). The LONG group showed a significant increase in [Formula: see text] (P < .05). These results suggest that repeated sprint training with insertion of longer rest periods is an efficient strategy for improving maximal power output compared with the same training separated by short rest periods alone.