The 30-minute Time Trial As A Predictor Of Ventilatory Threshold Running Velocity And Heart Rate

Abstract

Lactate threshold (LT) and ventilatory threshold (VT) heart rate and running velocity can be useful in the prescription of exercise intensity for endurance athletes. However, few coaches and athletes have access to the resources necessary to conduct these tests. Limited evidence is available which suggests that the results from running a 30-minute time trial can be used to estimate both heart rate and running velocity at LT. PURPOSE: To determine if running a 30-minute time trial accurately estimates the heart rate and running velocity at VT. METHODS: Twenty healthy, competitive runners (men, n = 10; women, n = 10) with a minimum of 5 years of long distance running experience were recruited to perform a treadmill VT protocol and a 30-minute time trial. The treadmill VT protocol proceeded until volitional fatigue (1% grade, 3 minute stages, 0.22 m/s increases per stage), with VT defined as the point immediately preceding the first non-linear increase in ventilation (VE) plotted against oxygen consumption (VO2). During a separate visit, participants completed a maximal effort 30-minute time trial on a 400 meter outdoor track with mean running velocity determined by the total distance traveled in the time allotted and heart rate data continuously collected with a heart rate monitor (RS800CX, Polar Electro Inc., Lake Success, NY). RESULTS: A significant, positive Pearson Product Moment correlation was found between the running velocity at VT and the mean running velocity of the 30-minute time trial (r = 0.95; p < 0.05) as well as the heart rate at VT and the average heart rate of the last 20-minutes of the time trial (r = 0.69; p < 0.05). The standard errors of the estimate (SEE) for the prediction of running velocity at VT and heart rate at VT from the 30-minute time trial were 0.15 m/s and 5.7 beats/min, respectively. CONCLUSIONS: These data demonstrate that a 30-minute time trial is a valid predictor of VT heart rate and running velocity. Supported by a Faculty-Student Summer Collaboration Grant from the Center for Scholarship and Teaching and the Faculty Development Committee of Elmhurst College