GLPG0492 is a selective androgen receptor modulator: the compound should help protect against (or help restore) muscle loss in case of immobilization (e.g. after orthopedic surgery) or due to aging (androgenic effect), but without anabolic effects (e.g. effect on testosterone). In the first part of the current study it will be tested whether GLPG0492 given orally to healthy male volunteers increases the protein synthesis in muscle, as measured by the uptake into the muscle of intravenously infused phenylalanine.