Effects of a Seven Day Overload-Period of High-Intensity Training on Performance and Physiology of Competitive Cyclists

Objectives: Competitive endurance athletes commonly undertake periods of overload training in the weeks prior to major competitions. This investigation examined the effects of two seven-day high-intensity overload training regimes (HIT) on performance and physiological characteristics of competitive cyclists. Design: The study was a matched groups, controlled trial. Methods: Twenty-eight male cyclists (mean +/- SD, Age: 33 +/- 10 years, Mass 74 +/- 7 kg, VO2 peak 4.7 +/- 0.5 L center dot min(-1)) were assigned to a control group or one of two training groups for seven consecutive days of HIT. Before and after training cyclists completed an ergometer based incremental exercise test and a 20-km time-trial. The HIT sessions were,120 minutes in duration and consisted of matched volumes of 5, 10 and 20 second (short) or 15, 30 and 45 second (long) maximal intensity efforts. Results: Both the short and long HIT regimes led to significant (p<0.05) gains in time trial performance compared to the control group. Relative to the control group, the mean changes (+/- 90% confidence limits) in time-trial power were 8.2% +/- 3.8% and 10.4% +/- 4.3% for the short and long HIT regimes respectively; corresponding increases in peak power in the incremental test were 5.5% +/- 2.7% and 9.5% +/- 2.5%. Both HIT (short vs long) interventions led to non-significant (p. 0.05) increases (mean +/- SD) in VO2 peak (2.3% +/- 4.7% vs 3.5% +/- 6.2%), lactate threshold power (3.6% +/- 3.5% vs 2.9% +/- 5.3%) and gross efficiency (3.2% +/- 2.4% vs 5.1% +/- 3.9%) with only small differences between HIT regimes. Conclusions: Seven days of overload HIT induces substantial enhancements in time-trial performance despite non-significant increases in physiological measures with competitive cyclists.