Fig. 2.

An overview of the energetic contributors to exercise is reported in 10-s averages for the “severe” (top panel), “heavy” (medium panel), and “moderate” (bottom panel) exercise intensity domain. White columns represent directly measured VO₂. Grey columns indicate the O₂ cost requested by ventilation. The black dashed line displays the energy provided by glycolytic sources over 3 min segments. Finally, the black solid line represents the adjusted cost of exercise accounting for both aerobic and glycolytic energy sources. Please note that during all the first 3 min segments, the contribution of immediate energy sources (O₂ and phosphocreatine) was not accounted and was probably the cause of the lower adjusted VO₂ between the first and the successive time segments [8, 22]