BACKGROUND: Although strength training (ST) enhances physical function in the elderly, little is known about the effect of training intensity on training and detraining adaptations in musculoskeletal fitness. OBJECTIVE: To determine the effect of exercise intensity on strength, anaerobic power, and mobility of older men subjected to a 24 week ST protocol followed by prolonged detraining. METHODS: Fifty two healthy but inactive older men (mean (SD) age 71.2 (4.1) years) were assigned to a control (n = 14), low intensity training (LIST; n = 18; 55% 1RM), or high intensity training (HIST; n = 20; 82% 1RM) group. They carried out a 24 week, whole body (10 exercises, two to three sets/exercise) ST programme followed by a 48 week detraining period. Upper and lower body strength, anaerobic power (Wingate testing), and mobility (timed up and go, walking, climbing stairs) were measured at baseline and immediately after training and during detraining. RESULTS: Although low intensity training improved (p<0.05) strength (42-66%), anaerobic power (10%), and mobility (5-7%), high intensity training elicited greater (p<0.05) gains (63-91% in strength, 17-25% in anaerobic power, 9-14% in mobility). All training induced gains in the LIST group had been abolished after four to eight months of detraining, whereas in the HIST group strength and mobility gains were maintained throughout detraining. However, anaerobic power had returned to baseline levels after four months of detraining in both groups. CONCLUSIONS: Higher intensity training protocols induce greater gains in strength, anaerobic power, and whole body physical function of older men. Moreover, higher intensity training may maintain the gains for more prolonged periods after training ceases.