INTRODUCTION: Systematic reviews (SR) and meta-analyses (MA) of randomized controlled trials (RCTs) have reported the benefits of carbohydrate (CHO) consumption in various endurance athletes, mainly cyclists or runners. Gathering existing reviews, the present systematic review tends to determine the best conditions and characteristics of this CHO ingestion to optimize athletes` performance. EVIDENCE ACQUISITION: A comprehensive search was conducted on five databases (from inception up to September 05, 2024) to identify related SR and MA of RCTs investigating the association between CHO consumption and performance. The quality of SRs was evaluated using the AMSTAR2. EVIDENCE SYNTHESIS: Fifteen SR, including 8 MA were included, gathering 262 RCTs and 521 single trials. The overall reviews` quality was rated low or critically low (11 reviews, 73%). All the measurements performance were conducted in the form of a Time Trial (69%) or a Time to Exhaustion (31%). A total of 102 studies (44%) revealed significant positive effect of CHO consumption on performance, with no difference between the performance modalities or sports practices. Consumption of complex CHO (fructose + glucose) improved performance compared with simple CHO or other combinations. Consumption introduced during efforts lasting 1 to 2 hours (57 trials) and 2 to 4 hours (70 trials) seem to favor better performances. CONCLUSIONS: The present review of SR and meta-analysis clarifies the conditions of CHO ingestion to optimize endurance athletes` performances, especially pointing its interest for efforts lasting 1 to 4 hours and of complex CHO formulations. More rigorous research remains however needed to transfer research results to the real practise of athletes.
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