Dose-Response Relationship Between Interval Training Frequency And Lactate Threshold

Abstract

Endurance performance is determined by numerous factors, including maximal oxygen uptake (VO2max), economy, and lactate threshold (LT). Many researchers agree that LT is among the best predictors of performance in endurance-related events (Midgley et al., 2007), yet the attributes of a training program aimed at positively modifying LT are not well understood. PURPOSE: The purpose of this study was to determine if interval training at 110-120% above peak power output one and two days per week would elicit improvements in LT. METHODS: Participants (N=34) were randomized to either a control group or 6 wk interval training group (1 day/wk or 2 days/wk). Interval training on a cycle ergometer was performed at 110-120% peak workload. Participants were instructed to not change their usual physical activity habits or diet throughout the study. Primary outcome measures (VO2max, LT at %VO2max, peak workload) were analyzed using a two-factor mixed ANOVA, with the between factor "experimental group" and repeated factor "trial" (baseline, 6 wk).TABLE: Physiological characteristics at baseline and 6 wk for control and interval training groups (mean ± SD).RESULTS: Physiological characteristics at baseline and 6 wk for participants in each experimental group are presented in the Table. After 6 wk, LT (%VO2max) increased significantly (p < 0.05) in both 1 day/wk (3.8 ± 3.1%) and 2 days/wk (7.7 ± 2.7%) groups. There was a significant interaction between exercise frequency and LT (%VO2max) values (p < 0.05) indicating that LT responded differently to 1 day/wk and 2 days/wk of interval training. CONCLUSION: Our findings demonstrate that high-intensity, interval training may be a successful strategy for modifying LT. Moreover, our results suggest that there is a dose-response relationship between frequency of interval training and the magnitude of LT improvement.