Introduction: Male elite cyclists (average VO₂-max: 71 ml/min/kg, n=18) completed seven weeks of high-intensity interval training (HIT) (3x/week; 4-min and 30-s intervals) during the competitive part of the season. The influence of a maintained or lowered total training volume combined with HIT was evaluated in a two-group design. Weekly moderate-intensity training was lowered by ~33% (~5 hours) (LOW, n=8) or maintained at normal volume (NOR, n=10). Endurance performance and fatigue resistance was evaluated via 400 kcal time-trials (~20 min) commenced either with or without prior completion of a 120-min preload (including repeated 20-s sprints to simulate physiologic demands during road races).

Results: Time-trial performance without preload was improved after the intervention (p=0.006) with a 3% increase in LOW (p=0.04) and a 2% increase in NOR (p=0.07). Preloaded time-trial was not significantly improved (p=0.19). In the preload, average power during repeated sprinting increased by 6% in LOW (p<0.01) and fatigue resistance in sprinting (start vs end of preload) was improved (p<0.05) in both groups. Blood lactate during the preload was lowered (p<0.001) solely in NOR. Measures of oxidative enzyme activity remained unchanged, whereas the glycolytic enzyme PFK increased by 22% for LOW (p=0.02).

Conclusion: The present study demonstrates that elite cyclists can benefit from intensified training during the competitive season both with maintained and lowered training volume at moderate intensity. In addition to benchmarking effects of such training in ecological elite settings, the results also indicate how some performance and physiological parameters may interact with training volume.