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 14 male elite cyclists (age 22.4±3.4 years, height 181±6 cm, weight (69.2±6.8 kg, VO₂max 69±7 ml·min^-1·kg^-1) during an incrememtal exercise test (20 W-min^-1). Heart rate and oxygen uptake were assessed at the following ventilatory parameters: 1. Steeper increase of VC0₂ as compared to V0₂ (V-slope-method); 2. Respiratory exchange ratio (RQ) = 0.95 and 1.00; 3. VE/V0₂ increase without a concomitant VE/VC0₂ (VE/V0₂ method). Three weeks following the laboratory tests, the ability to maintain high-imtensity exercise was determined during a 40 km time trial on a bicycle. During this time trial the mean heart rate (HR_TT) and the road racing time (TT) were assessed. The V-slope-method and the VE/V0₂ method showed significant correlations with TT (V-slope: r = -0.82; p<0.001; 90 % interval of confidence =±82sec; VE/ VO₂:r = -0.81; p<0.01; 90 % interval of confidence =±81 sec). Heart rate at the ventilatory parameters and at tine maximum heart rate (HR_max) showed significant correlatioms with HR_TT. 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).

Key words

Ventilatory threshold - cyclists - performance - V-slope-method