Habitual carbohydrate ingestion reduces the efficacy of oral carbohydrate rinsing during repetitions to failure

Carbohydrate mouth rinsing has been reported to enhance exercise performance although individual variation exists. The present study aimed to investigate the effect of habitual dietary carbohydrate intake on the efficacy of rinsing a 6% carbohydrate solution on the number of bench press repetitions to failure at 60% of 1‐RM. Twenty‐one recreationally active male participants (Mean ± SD) (age: 24 ± 4 years, height: 177.8 ± 7.8 cm, body mass: 78.6 ± 8.1 kg; bench press 1‐RM: 73.3 ± 20.5 kg) performed bench press repetitions to failure at 60% 1‐RM following rinsing with 25 mL of a 6% carbohydrate (CHO), an artificially sweetened solution (PLA) and a non‐rising control condition (CON) in a randomised cross‐over design. A 7‐day dietary record was completed prior to the first session and subsequently analysed for daily carbohydrate consumption. The number of repetitions performed during CHO (24 ± 4) was higher than CON [21 ± 4; p < 0.001; 95% CI: 1, 4; d = 0.64], as was PLA [23 ± 4; p = 0.002; 95% CI: 1, 3; d = 0.48]. However, there was a large, negative relationship [r = −0.68 (95% CI: −0.86, −0.36), p < 0.001] between daily relative carbohydrate intake (g kg−1) and the difference in the number of repetitions between CHO and PLA. The present study suggests the existence of an inverse relationship between daily carbohydrate ingestion and the efficacy of carbohydrate mouth rinsing; participants who consumed the most daily carbohydrate were generally less likely to see an increase in performance with carbohydrate rinsing.