16 inactive frail older adults participated in this double-blind randomized exploratory trial. All participants received a 12-week program of 2 supervised resistance trainings a week. One group received only whey protein supplementation (WH group), the other received whey protein and creatine supplementation (WH+CR group). Protein supplementation totalled 20 g/d, creatine supplementation totalled 5 g/d. The WH-group received daily whey protein with a placebo for creatine. Muscle function (hand grip strength, timed stands and timed up and go test), bone mineral density and body composition were measured before and after the intervention.

No significant between-group differences were found. Significant improvements were found in both groups for all muscle function assessments, with an improvement on at least two out of three assessments for each individual participant. No significant improvements were found in body composition or bone mineral density. Adherence to the supplementations was 100%, with no reported severe adverse effects.