A randomized interventions study using a crossover design. Ten well trained triathletes or bikeriders will be included for to undergo two trail separated by about 3 weeks. The night before the trail each subject will performe a high intense interval trainings session on an ergometer bike. during the night an infusion of aminoacid tracers will be initiated. The subject is woken at 6.30 a.m. Blood samples and a musclebiopsy will be collected prior to the morning bike ride at 8.00a.m. Immediately before the morning bike ride is started the subject will ingest a drink of 0,5g protein or a non-caloric placebo (random order). During the bike ride and the following 4,5 hours blood will be drawn with regular intervals. at time point 0, 60 and 180 min after the training session biopsies are collected.