The experimental design will consist of the following: 1) maximal ramp incremental test, to determine peak power output of each subject. 2) pre training test with blood samples, maximal incremental test (Incr) to determine the whole-body fat oxidation kinetics and Fatmax in the first phase (IncrP1) and the maximal parameters in the second phase (IncrP2) of the test. 3) 2-wk training intervention, Fatmax or HIIT and 4) post-training test, control maximal incremental test with blood samples.