Figure 2a-d. Acute response for La (a), HR (b), VO₂ (c), and RER (d) to long HIIE, short HIIE, and CE. Values are means ± SD. The specific exercise modes were conducted from min 13 to 41 after a standardized warm up phase. In the 4 x 4 min HIIE, one subject finished the peak workload phase of the fourth interval prematurely after 2 min because of exhaustion. La, blood lactate; HR, heart rate; VO₂, oxygen uptake; RER, respiratory exchange ratio; HIIE, high-intensity interval exercise; CE, continuous exercise; P_max, maximum power output from the incremental exercise test; LTP₁ and LTP₂, first and second lactate turn point from the incremental exercise test