AIM: This study aimed to quantify the cardiorespiratory, metabolic and hormonal responses of elite open-wheel indoor kart racers.METHODS: Ten male racers (age: 21±3 yrs; height: 1.92±0.06 m, body mass: 76.0±5.9 kg) participated in a racing tournament. Their peak oxygen uptake and heart rate were assessed by a ramp test (100 W, increase 30 W·min-1) in the laboratory. During the racing itself, the cardio-respiratory and accelerometer values were recorded and pre- and post-race levels of blood lactate and salivary cortisol were determined.RESULTS: The average peak values for all of the drivers with respect to oxygen uptake and heart rate were 4.5±0.8 L·min-1 (56.7±7.9 mL·min-1·kg-1) and 193±5 beats·min-1, respectively. Overall, 28.3±3.3 laps were completed during 30-min of racing. Acceleration forces for the entire test averaged 1.20±0.51 G (maximum: 3.30 G), declining from the first 10 min until the end of racing (P<0.03). The oxygen uptake (~20 mL·min-1·kg-1), heart rate (~133 beats·min-1), respiratory exchange ratio (~0.96) and ventilation (~70 L·min-1) observed indicated moderate cardio-respiratory responses. Blood lactate concentration was significantly higher after the race than before but remained at <2 mmol·L-1 (P<0.01; effect size: 1.62).CONCLUSION: There were no differences between salivary cortisol levels before and after the race (P<0.06; effect size: 0.49). Directly after the race, the drivers rated their perceived exertion on Borg’s scale as 11.1±1.3. The present data revealed that the psycho-physical exertion associated with a 30-min open-wheel indoor kart race is moderate.
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' P-mean declined from the first to the third interval (P < 0.05), whereas P-mean was unaltered under the HoHOX, NoHOX and NoNo conditions. We conclude that the less pronounced decline in P-mean during 3 x 3-min double-poling sprints in normoxia and hypoxia with hyperoxic recovery is not related to changes inmuscle 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.