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

The purpose of this study was to investigate the validity of the ventilatory response during incremental exercise as indication of endurance performance during prolonged high-intensity exercise under field test conditions in elite cyclists. The ventilatory threshold (VT) was assessed in 74 male elite 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 incremental exercise test (20 W . min(-1)). Heart rate and oxygen uptake were assessed at the following ventilatory parameters: 1. Steeper increase of VCO2 as 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 concomitant VE/VCO2 (VE/(V) over dotO(2) method). Three weeks following the laboratory tests, the ability to maintain high-intensity exercise was determined during a 40 km time trial on a bicycle. During this time trial the mean heart rate (HRTT) and the road racing time (TT) were assessed. The V-slope-method and the VE/(V) over dotO(2) method showed significant correlations with TT (V-slope: r = - 0.82; p < 0.001; 90% interval of confidence = +/-82 sec; 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 heart rate (HRmax) showed significant correlations with HRTT. The V-slope-method is the preferred method to predict heart rate during prolonged high-intensity exercise (r = 0.93; p < 0.0001; 90% interval of confidence: +/-4.8 beats . min(-1)). For predicting heart rate during prolonged high-intensity exercise using an incremental exercise test (20 W . min(-1)), without the knowledge of ventilatory parameters, we recommend using the regression formula: H-TT = 0.84 . H-max + 14.3 beats . min(-1) (r = 0.85; p < 0.001).