Te-Sheng Chen

Background: Researchers have studied practical applications of high-intensity interval training and hypoxic training. PGC-1α, IGF-I, and HIF-1α are generated from high-intensity interval training and affect muscle cells. Altitude training also produces HIF-1α, which induces erythropoietin and increases the number of red blood cells. However, due to the limit on training intensity and cycle, it was replaced by normobaric hypoxia training. Purpose: To investigate the effects of 2-day high-intensity interval training on muscular anaerobic metabolism at varying oxygen concentrations for 2 days. Method: Ten subjects performed 2 consecutive days of intermittent hypoxia-hyperoxic training (IHHT); intensity of training was determined by the sprint test results. IHHT comprised 4 sets of 3 repetitions for 40 seconds (4 × 3 × 40 s); the intensity and oxygen concentration were 80% of maximal effort and 13% oxygen for the first and third sets, and were 90% of maximal effort and 21% oxygen for the second and fourth set; participants walked for 3 min wearing an oxygen mask (O2 80%) before each set. Differences in biological parameters between the two days of training was analyzed by t-test. Results: The difference of mean lactate levels between two days were 0.96 ± 0.75 mmol/l at Set 3 (P = .003) and 1.05 ± 1.12 mmol/l at Set 4 (P = .016), respectively. Mean ammonia concentrations at Set 4 were 117.70 ± 29.8 μmol/l for the first day and 94.50 ± 14.45 μmol/l for the second day (P = .057). The difference of heart rate were 4.20 ± 5.05 min-1 at Set 1 (P = .027) and 4.00 ± 5.48 min-1 at Set 2 (P = .046). Conclusions: Two-day intermittent hypoxia-hyperoxic training affected lactate and heart rate.