Acute Physiological Response to Different Sprint Training Protocols in Normobaric Hypoxia

Background: the purpose of this study was to examine acute physiological responses to and the performance effects of two sprint training protocols in normobaric hypoxic conditions. Methods: Healthy competitive female (n = 2) and male (n = 5) kayakers (19 ± 2.1 years) performed four sprint training sessions on a kayak ergometer over a period of two weeks. Participants performed five sets of 12 × 5 s sprints or 3 × 20 s sprints in both normobaric normoxic (NOR, F(i)O(2) = 20.9%) or normobaric hypoxic (HYP, F(i)O(2) = 13.6%) conditions. The peak power output (PPO), rate of perceived exertion (RPE), and heart rate (HR) of each participant were monitored continuously. Their blood lactate concentrations ([BLa(+)]), in addition to their blood gas (mixed-venous partial pressure (p) of carbon dioxide (pCO(2)), O(2) (pO(2)), and oxygen saturations (sO(2))) were collected before and after exercise. Results: A significantly greater RPE, HR, and [BLa(+)] response and a significant decrease in pCO(2), pO(2), and sO(2) were observed in HYP conditions versus NOR ones, independent of the type of training session. The PPO of participants did not differ between sessions. Their RPE in HYP12 × 5 was greater compared to all other sessions. Conclusions: The HYP conditions elicited significantly greater physiological strain compared to NOR conditions and this was similar in both training sessions. Our results suggest that either sprint training protocol in HYP conditions may induce more positive training adaptations compared to sprint training in NOR conditions.