Figure 1. Maximal running speed (V), peak heart rate (HR), blood lactate ([La]) and rating of perceived exertion (RPE) reached with each protocol, expressed as a percentage of the values reached at the end of the original 30-15. *: p < 0.05 vs. 30-15, † : p < 0.05 vs. 30-15, ‡: difference vs. 30-15 with effect size considered as moderate (>0.5)