Supplementary file 1_Creatine supplementation in young men under resistance versus non-resistance training: a systematic review and meta-analysis of strength, performance, and lean mass.docx

BackgroundCreatine is a highly marketed ergogenic aid that has strengthening and high-intensity training effects. However, past meta-analyses have often grouped together heterogeneous training modalities, and it was not known if the training context has a modifying effect on body composition and performance.
MethodsThis systematic review and meta-analysis pooled RCT evidence in healthy men aged 18–30 years old to quantify the effects of creatine supplementation in terms of body composition, maximal strength, and exercise performance. All the databases were searched up to 1 October 2025, and 39 eligible trials were discovered. The context of training was prespecified—RT vs. non-RT, and used as the main comparison. Pooled estimates were made using random effects models for FFM, LBM, and Wingate peak and mean power, CMJ, and 1RM outcomes. The exploratory subgroup analyses were done to investigate whether training condition and intervention duration moderated the effects.
ResultsThe number of trials that were considered according to the inclusion criteria was thirty-nine. When using RT, creatine supplementation led to significant gains in FFM (+3.39 kg) and LBM (+2.70 kg), but not to significant gains in non-RT conditions. Wingate peak and mean power both increased in both contexts (peak power +71.27 W; mean power +39.69 W), with no evidence that training context modified these results. CMJ showed a pooled improvement of 2.87 cm; however, this estimate should be interpreted with caution due to high heterogeneity (I2 = 88.5%). Exploratory analyses suggested that more consistent effects may occur in interventions lasting at least 8 weeks.
ConclusionThe supplementation with creatine leads to an increase in anaerobic power regardless of the training environment, but the gains in body composition depend on parallel RT. In practice, creatine in association with RT is recommended for lean mass gains, while either anaerobic performance benefit could be obtained in different training modalities.
Systematic review registrationThe study was prospectively registered in PROSPERO (CRD420261283973). The registration URL is: https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=1283973.