5'-UMP inhibited muscle atrophy due to detraining: a randomized, double-blinded, placebo-controlled, parallel-group comparative study

A short period of disuse of 1-2 weeks due to factors such as illness or injury can lead to muscle atrophy, affecting both athletic performance and health. Recent research has shown that uridine 5'-monophosphate (5'-UMP) can counteract disuse-induced muscle atrophy by increasing PGC-1α expression and inhibiting atrogin-1 expression. However, the effect of 5'-UMP on disuse muscle atrophy in humans remains unknown. Therefore, the aimed of this study was to explore the effects of 5'-UMP supplementation during detraining on short-term disuse muscle atrophy in healthy men. Following a 6-week resistance training program on upper arm, healthy men were randomized to either a UMP group ( = 11) or a placebo group ( = 10), taking their respective supplements during the 2-week detraining period. Muscle thickness, an indicator of muscle hypertrophy and atrophy, was measured at 3 positions (MT50, MT60, and MT70) at baseline, 1 week, and 2 weeks after detraining. Both groups showed a significant decrease in muscle thickness at MT70. The relative decrease was greater in the placebo group (2.4 ± 2.8%) than in the UMP group (0.0 ± 2.0%), significantly ( = 0.034) at 1 week. However, no significant difference was observed at MT50 and MT60. After the hypertrophy, 5'-UMP may prevent muscle atrophy due to the detraining within the first week.