Recommended but Not High Carbohydrate Dose Improves Performance After Heavy‐ but Not Moderate‐Intensity Exercise in Recreationally Trained Participants

ABSTRACT This study determined: (i) whether carbohydrates (CHO) supplementation had beneficial effects on endurance performance, as assessed by a time trial (TT) test, following exercise bouts within either the moderate‐ or heavy‐intensity exercise; and (ii) if above the recommended dose of CHO supplementation would impact endurance performance. Twelve recreationally trained males underwent: (i) a step‐ramp‐step test to estimate gas exchange threshold (GET) and maximal metabolic steady state (MMSS est ); (ii) 9 randomized visits consisting of 3 different constant power output (PO) bouts: within the moderate‐ (120 min at 90% of GET [MOD]); lower portion of the heavy‐ (90 min at Δ20% between GET and MMSS est [HVY 1 ]); and higher portion of the heavy‐ (60 min at Δ80% between GET and MMSS est [HVY 2 ]) intensity domain under 3 different conditions (placebo, recommended 40 g/h CHO [R‐CHO], and high 90 g/h CHO [H‐CHO]) dose per intensity with a subsequent 4 km TT. The 4 km TT was improved ( p = 0.017) in the R‐CHO (8.3 ± 0.7 min) compared to placebo (8.6 ± 0.9 min) after HVY 1 but not in the H‐CHO (8.5 ± 0.9 min) condition. In contrast, 4 km TT performance was not different after MOD (placebo = 8.8 ± 1.3 min; R‐CHO = 8.6 ± 1.1 min; H‐CHO = 8.6 ± 1.1; p = 0.589) or HVY 2 (placebo = 8.8 ± 1.1 min; R‐CHO = 8.6 ± 0.9 min; H‐CHO = 8.7 ± 1.0; p = 0.465). In recreationally trained individuals, R‐CHO supplementation improved 4 km TT performance following exercise within the lower portion of the heavy‐intensity domains, but not following exercise in the moderate‐ or upper region of the heavy‐intensity domain. Additionally, above‐recommended CHO dose was no longer beneficial for performance regardless of the prior exercise intensity bout.