Cardiorespiratory, metabolic and hormonal responses during open-wheel indoor kart racing

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 (similar to 20 mL.min(-1).kg(-1)), heart rate (similar to 133 beats.min(-1)), respiratory exchange ratio (similar to 0.96) and ventilation (similar to 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.