Submaximal Blood Lactate and Heart Rate Measurements as Indicators of Training Status in College Distance Runners

Seven highly trained male college distance runners were studied throughout a competitive cross-country season. Common laboratory and field measurements were used to assess their physiological adaptation to training. They were tested before (pre), during (mid), and at the end of the competitive season (post) for peak oxygen consumption (V̇O₂peak), running economy (RE), fractional utilization of the aerobic capacity (%V̇O₂peak), and time to exhaustion (TTE). One or 2 days prior to each scheduled competition, submaximal heart rate (HR) and submaximal blood lactate accumulation (bLa) were determined during a 1.61-km (1 mile) run on an indoor track. Five subjects ran at a 17.6-km·hr^-1 pace while the other 2 ran at a 16.1-km·hr^-1 pace, which corresponded to an estimated mean (±SE) intensity of 83.1% (±4.4) of preseason V̇O₂peak. V̇O₂peak, RE, %V̇O₂peak, and TTE all improved significantly over the season (p < 0.05). The field measures of HR and bLa remained unchanged during this same period. These results suggest that the field trials employing single HR and single bLa measurements (<80-85% V̇O₂peak) were not sensitive to changes in endurance capacity in 7 highly trained distance runners.