Predicting lactate threshold using ventilatory threshold

Abstract

Lactate threshold is an important reference point when setting training intensities for endurance athletes. Ventilatory threshold has been used as a noninvasive estimate of lactate threshold, but appears to underestimate training intensity for many athletes. This study evaluated whether data obtained during a noninvasive, maximal exercise test could be used to predict lactate threshold. Maximal oxygen consumption (55+/-2 ml O(2) x kg(-1) x min(-1)) and heart rate at the ventilatory threshold (V-slope method) were determined for 19 cyclists (10 men, 9 women, 35+/-2 years). Cyclists also performed a lactate threshold test, consisting of 8 min stages at power outputs below, at, and above the ventilatory threshold. Heart rate associated with the lactate threshold was determined using the Dmax method. The correlation coefficient between heart rates at the ventilatory and lactate thresholds was 0.67, indicating 45% shared variance. The best fitting model to predict heart rate at the lactate threshold included heart rate at the ventilatory threshold, gender, body weight, and an interaction between gender and body weight. Using this model, R(2) was 0.70. Thus, heart rate at the ventilatory threshold may be adjusted to more accurately predict a heart rate that corresponds to the lactate threshold for recreational cyclists.