Participants will be divided in two-treatment groups 1) Hydrolysed meat-protein + whey (PROT); and 2) non-protein iso-energetic placebo (CHO). Once considered eligible for the study, and after an initial familiarisation period plus baseline tests (endurance performance body composition and blood extractions) participants will be randomly assigned to one of the intervention groups: PROT and CHO. Each group will follow a 10-week periodised endurance training intervention combined with one of the two specific supplementation treatments (PROT or CHO). Measurements of performance (VO2peak, vetilatory threshold and time to exhaustion at maximal aerobic intensity), body composition (fat and fat free mass), microbiota and haematology will be determined before and after the 10-week intervention period.