The ventilatory threshold, heart rate, and endurance performance: Relationships in elite cyclists

The purpose of this study was to investigate the validity of the ventilator y response during incremental exercise as indication of endurance performan ce during prolonged high-intensity exercise under field test conditions in elite cyclists. The ventilatory threshold (VT) was assessed in 74 male elit e cyclists (age 22.4 +/- 3.4 years, height 181 +/- 6 cm, weight 69.2 +/- 6. 8 kg, (V) over dotO(2)max 69 +/- 7 ml . min(-1) . kg(-1)) during an increme ntal exercise test (20 W . min(-1)). Heart rate and oxygen uptake were asse ssed at the following ventilatory parameters: 1. Steeper increase of VCO2 a s compared to to (V)over dotO(2) (V-slope-method); 2. Respiratory exchange ratio (RQ) = 0.95 and 1.00; 3. VE/(V) over dotO(2) increase without a conco mitant VE/VCO2 (VE/(V) over dotO(2) method). Three weeks following the labo ratory tests, the ability to maintain high-intensity exercise was determine d during a 40 km time trial on a bicycle. During this time trial the mean h eart rate (HRTT) and the road racing time (TT) were assessed. The V-slope-m ethod and the VE/(V) over dotO(2) method showed significant correlations wi th TT (V-slope: r = - 0.82; p < 0.001; 90% interval of confidence = +/-82 s ec; VE/(V) over dotO(2):r = - 0.87; p < 0.01; 90% interval of confidence = +/-81 sec). Heart rate at the ventilatory parameters and at the maximum hea rt rate (HRmax) showed significant correlations with HRTT. The V-slope-meth od is the preferred method to predict heart rate during prolonged high-inte nsity exercise (r = 0.93; p < 0.0001; 90% interval of confidence: +/-4.8 be ats . min(-1)). For predicting heart rate during prolonged high-intensity e xercise using an incremental exercise test (20 W . min(-1)), without the kn owledge of ventilatory parameters, we recommend using the regression formul a: H-TT = 0.84 . H-max + 14.3 beats . min(-1) (r = 0.85; p < 0.001).