Preparation for the Tokyo Olympic Games: Is there an ergogenic potential of combining heat and hypoxic acclimation?

A combined stressor heat and hypoxia acclimation protocol has been proposed as a "conditioning cocktail" for aerobic performance in thermoneutral conditions (1). Heat acclimation-elicited thermoregulatory benefits have been shown not to be negated by adding daily exposure to hypoxia (2). These observations may lure athletes to incorporate such protocols on the road to the Tokyo Olympics. Whether a combined stressor approach could indeed enhance aerobic performance in hot environments remains unresolved. METHODS: Eight trained males (VO2max: 54.3 ± 5.8 mL·min-1·kg-1, Wpeak: 343 ± 30 W) underwent a 10-day normobaric hypoxic confinement interspersed with daily 90-min normoxic controlled-hyperthermia (target rectal temperature: 38.5°C) exercise sessions (live high (13.5% FiO2)-train warm (35°C) and low: LH-TWL). Prior to and following the confinement, the participants were tested on a cycle ergometer in normoxic (23°C, 50% RH, 20.9% FiO2; NOR), hypoxic (23°C, 50% RH, 13.5% FiO2; HYP) and hot (35°C, 50% RH, 20.9% FiO2; HE) conditions in a randomized and counterbalanced order. The exercise tests consisted of two stages; a 30-min steady-state exercise followed by incremental exercise to exhaustion. The steady-state exercise was performed at 40% NOR Wpeak to evaluate thermoregulatory function and exercise economy. Hematocrit and hemoglobin concentration were assessed from venous blood samples obtained immediately before and after the confinement. The anaerobic threshold was defined as the oxygen uptake that corresponded to the deflection point of the end-tidal PETCO2 confirmed by the nadir in the VE/VCO2 when plotted as functions of the workload during the incremental test. Ten control participants (VO2max: 57.9 ± 6.2 mL·min-1·kg-1, Wpeak: 375 ± 49 W) completed the same test in the same environments before and after 10 days comprising daily volume-matched training sessions in thermoneutral normoxic conditions without hypoxic exposure (CON). RESULTS: VO2max and the anaerobic threshold did not increase in any environmental condition following LH-TWL. In contrast, Wpeak increased by 6.3 ± 3.4% in NOR and 4.0 ± 4.9% in HE, respectively. The forehead sweating response was augmented in HE as reflected on the higher values of peak sweat rate and the gain of the sweating response. Similar thermoregulatory and performance gains were observed in the CON group. Exercise economy increased post-acclimation in NOR after LH-TWL only. The estimated plasma volume contracted by 15.1 ± 8.5% after LH-TWL, whereas it expanded by 10.7 ± 7.2% in CON. CONCLUSION: A 10-day combined heat and hypoxia acclimation protocol did not confer any additional benefit over training in normoxic thermoneutral conditions. Thus, adoption of such a training protocol as an ergogenic aid in preparation for the Tokyo Olympics does not seem warranted.
© Copyright 2019 Book of Abstracts of the 24th Annual Congress of the European College of Sport Science - 3rd - 6th July 2019, Prague - Czech Republic. Julkaistu Tekijä European College of Sport Science. Kaikki oikeudet pidätetään.

Aiheet: kesäolympialaiset 2020 adaptaatio lämpötila happivaje ergogeeninen apu
Aihealueet: biologiset ja lääketieteelliset tieteet
Julkaisussa: Book of Abstracts of the 24th Annual Congress of the European College of Sport Science - 3rd - 6th July 2019, Prague - Czech Republic
Toimittajat: V. Bunc
Julkaistu: Prag European College of Sport Science 2019
Julkaisutyypit: kongressin muistiinpanot
Kieli: englanti (kieli)
Taso: kehittynyt