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

This study aimed to quantify the cardiorespiratory, metabolic and hormonal responses of elite open-wheel indoor kart racers.

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.

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).

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.