Experimental V’O<sub>2</sub> and simulated muscle V’O<sub>2</sub>, metabolite concentrations and ATP usage/supply fluxes during low-intensity (baseline) and high-intensity cycling exercise in untrained and trained muscle.

<p>(A) Experimental and simulated V’O<sub>2</sub>, simulated ADP and pH. (B) Simulated PCr, P<sub>i</sub> and ATP. (C) Simulated ATP usage (UT), ATP supply by OXPHOS (OX), ATP supply by anaerobic glycolysis (GL), ATP supply by creatine kinase (CK). Experimental baseline-heavy-intensity exercise transition: after 3 min. Simulated baseline-heavy-intensity exercise transition: after 3.4 min (the delay by 24 s corresponds to the cardio-dynamic phase of the pulmonary V’O<sub>2</sub> on-kinetics). The muscle V’O<sub>2</sub> is calculated based on the assumption that during baseline-intensity exercise (20 W) muscle V’O<sub>2</sub> constitutes ~75% and during heavy-intensity exercise ~85% of the pulmonary V’O<sub>2</sub> (see Ref. [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0154135#pone.0154135.ref040" target="_blank">40</a>]).</p>