Negligible effects of fructose-glucose composite carbohydrates on performance across a prolonged soccer match simulation compared with a glucose-only control in semi-professional soccer players

Abstract

Higher carbohydrate availability, achieved through combined intake of glucose and fructose, has shown to enhance endurance performance. This study examined the effects of higher carbohydrate doses containing a fructose–glucose mixture (1:2 ratio) on performance during a 120-min simulated soccer match, compared to lower doses containing only glucose. Fifteen semi-professional soccer players (7 males, 8 females) completed two 120-min soccer-specific exercise sessions in a randomised and crossover design. Participants consumed either 60 g·h⁻¹ glucose, or a combination of 0.5 g∙min-1 fructose and 1.0 g∙min-1 glucose (90 g·h⁻¹) at pre-exercise, halftime, full-time, and midway through extra-time. Measures including gastrointestinal (GI) discomfort, mental fatigue, passing accuracy, neuromuscular performance (reactive strength index, countermovement jump height, peak power output), and sprint performance (15 and 30m sprints), were assessed at 0-min, 45-min, 90-min, and 120-min. Blood glucose and lactate concentrations were assessed every 15 min. Fructose–glucose co-ingestion elevated blood glucose concentration from 105 min (p=0.006, d=1.2), but did not maintain performance (p>0.05). GI symptoms of gastric reflux at 45-min (p=0.011, d=0.9), fullness at 90-min (p=0.013, d=0.9), and flatulence at 120-min worsened in glucose (p=0.003, d=1.1). Abdominal cramps were greater in fructose–glucose at 45-min (p<0.001, d=1.7) and 90-min (p<0.001, d=1.6). Although supplementation did not influence any other variables (p<0.05), countermovement jump height, peak power output and sprint performance was negatively influenced by exercise in both conditions (p<0.05). A higher carbohydrate dosage of fructose–glucose co-ingestion increases blood glucose concentrations but does not mitigate technical and neuromuscular performance impairments during a prolonged simulated soccer match