Abstract
Here, we evaluated the influence of breathing oxygen at different partial pressures during recovery from exercise on performance at sea-level and a simulated altitude of 1800 m, as reflected in activation of different upper body muscles, and oxygenation of the m. triceps brachii. Ten well-trained, male endurance athletes (25.3±4.1 yrs; 179.2±4.5 cm; 74.2±3.4 kg) performed four test trials, each involving three 3-min sessions on a double-poling ergometer with 3-min intervals of recovery. One trial was conducted entirely under normoxic (No) and another under hypoxic conditions (Ho; FiO2 = 0.165). In the third and fourth trials, the exercise was performed in normoxia and hypoxia, respectively, with hyperoxic recovery (HOX; FiO2 = 1.00) in both cases. Arterial hemoglobin saturation was higher under the two HOX conditions than without HOX (p<0.05). Integrated muscle electrical activity was not influenced by the oxygen content (best d = 0.51). Furthermore, the only difference in tissue saturation index measured via near-infrared spectroscopy observed was between the recovery periods during the NoNo and HoHOX interventions (P<0.05, d = 0.93). In the case of HoHo the athletes’ Pmean declined from the first to the third interval (P < 0.05), whereas Pmean was unaltered under the HoHOX, NoHOX and NoNo conditions. We conclude that the less pronounced decline in Pmean during 3 x 3-min double-poling sprints in normoxia and hypoxia with hyperoxic recovery is not related to changes in muscle activity or oxygenation. Moreover, we conclude that hyperoxia (FiO2 = 1.00) used in conjunction with hypoxic or normoxic work intervals may serve as an effective aid when inhaled during the subsequent recovery intervals.
Highlights
The influence of inhaling different partial pressures of oxygen on the activity and oxygenation of various muscle groups at different exercise intensities has beenPLOS ONE | DOI:10.1371/journal.pone.0140616 October 15, 2015Muscle Oxygenation and Double Poling characterized [1,2,3]
The only difference in the level of oxygenation (TSI) during the recovery periods was between NoNo, on the one hand, and the HoHOX and NoHOX conditions, on the other (d = 0.93)
In the present study all of our athletes exhibited a significant decline in Pmean during the 3 x 3-min double poling sprints in hypoxia with hypoxic recovery
Summary
The influence of inhaling different partial pressures of oxygen (i.e., hypoxia and hyperoxia) on the activity and oxygenation of various muscle groups at different exercise intensities has beenPLOS ONE | DOI:10.1371/journal.pone.0140616 October 15, 2015Muscle Oxygenation and Double Poling characterized [1,2,3]. The influence of inhaling different partial pressures of oxygen (i.e., hypoxia and hyperoxia) on the activity and oxygenation of various muscle groups at different exercise intensities has been. With more and more pronounced hypoxia, the changes in arterial oxygen saturation (SaO2) evoke cardio-respiratory efforts designed to compensate for the reduction in systemic O2 transport and counteract impairment of performance and muscle activity [7]. At the same time, breathing hyperoxic air elevates the amount of oxygen dissolved in the arterial plasma [8, 9], thereby potentially accelerating recovery. The physiological responses of athletes to high intensity exercise with intermittent hypoxic training as well as repeated sprints in hypoxia, have attracted increasing scientific interest [10,11,12]
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