Effects of Highly Branched Cyclic Dextrin-Based Carbohydrate and Protein Co-Ingestion on Endurance Capacity and Metabolic Response in Soccer Players: A Randomized Crossover Trial.
Co-ingestion of highly branched cyclic dextrin with whey protein isolate (CHOP) improved running time and distance and reduced RPE compared to placebo during soccer-specific intermittent exercise, while HBCD alone increased carbohydrate oxidation without improving endurance performance.
Key Findings
Results
CHOP significantly improved running time and running distance compared to placebo during soccer-specific intermittent exercise.
Nine male soccer players completed a randomized crossover trial with three conditions: Placebo (water), CHO, and isocaloric HBCD plus whey protein isolate (CHOP)
Running time improvement in CHOP vs. Placebo was statistically significant (p = 0.019)
Running distance improvement in CHOP vs. Placebo was statistically significant (p = 0.025)
No significant difference in running time or distance was observed between CHOP and CHO conditions
Exercise protocol was a standardized ~120-min laboratory-based soccer-specific intermittent protocol, not an actual match
Results
CHOP resulted in significantly lower ratings of perceived exertion (RPE) compared to Placebo during the latter stage of exercise.
RPE was significantly lower in CHOP than in Placebo during the latter stage of exercise (p = 0.016)
This suggests reduced perception of fatigue with HBCD plus whey protein co-ingestion
The RPE difference was observed specifically during the latter stage, not throughout the entire exercise bout
Results
CHO (HBCD alone) increased respiratory quotient and carbohydrate oxidation while reducing fat oxidation at the final exercise cycle compared to Placebo.
RQ was significantly higher in CHO vs. Placebo at the final cycle (p = 0.042)
Carbohydrate oxidation was significantly higher in CHO vs. Placebo at the final cycle (p = 0.048)
Fat oxidation was significantly lower in CHO vs. Placebo at the final cycle (p = 0.034)
These metabolic changes reflect greater late-exercise carbohydrate utilization with HBCD ingestion
Despite increased CHO utilization, CHO condition did not improve endurance performance compared to Placebo
Results
HBCD ingestion did not increase cardiovascular or gastrointestinal strain compared to Placebo.
Heart rate was assessed across conditions and no significant cardiovascular strain was associated with HBCD ingestion
Digestive symptoms were monitored and HBCD consumption before exercise and at half-time did not increase gastrointestinal symptoms
The authors attribute this to the 'favorable gastrointestinal properties' of HBCD
The 500-mL beverage was split into two 250-mL servings consumed before exercise and at half-time
Results
CHO alone (HBCD without protein) did not significantly improve endurance performance compared to Placebo despite altering substrate metabolism.
No significant difference in running time or running distance was found between CHO and Placebo conditions
CHO did produce significant shifts in RQ and substrate oxidation at the final cycle
This dissociation between metabolic effect and performance outcome suggests that carbohydrate availability alone was insufficient to improve fatigue-limited performance in this protocol
The study used a within-subjects crossover design with a washout period of at least 7 days between conditions
Methods
The study used a single-blind, randomized crossover design with nine male soccer players and a minimum 7-day washout period between conditions.
Sample size was n = 9 male soccer players
Three conditions were tested: Placebo (water), CHO (HBCD), and CHOP (HBCD plus whey protein isolate), with CHO and CHOP being isocaloric
Washout period between conditions was at least 7 days
Condition effects were tested via repeated-measures ANOVA at each exercise cycle
Outcomes measured included RQ, substrate oxidation, heart rate, RPE, digestive symptoms, running time, and distance
What This Means
This research suggests that combining highly branched cyclic dextrin (a specialized type of carbohydrate) with whey protein can meaningfully benefit endurance performance in soccer players during prolonged, intense intermittent exercise. In a controlled laboratory study, nine male soccer players completed a roughly two-hour soccer-specific exercise protocol under three different supplementation conditions — plain water, carbohydrate alone (HBCD), and an equal-calorie combination of HBCD plus whey protein. Players who consumed the carbohydrate-protein combination ran longer and farther than those who drank only water, and they also reported feeling less fatigued during the later stages of exercise. Notably, the carbohydrate-only condition did not produce these performance benefits, even though it did shift the body toward burning more carbohydrate and less fat late in the exercise session.
This research suggests that the addition of whey protein to HBCD carbohydrate may provide an extra ergogenic (performance-enhancing) effect during prolonged soccer-specific exercise that carbohydrate alone does not. The HBCD-based drinks were also well-tolerated, with no increase in stomach or digestive discomfort and no additional cardiovascular stress compared to water. This is relevant because gastrointestinal problems are a common concern with carbohydrate supplementation during exercise, and HBCD's structural properties appear to allow it to be consumed without these side effects.
This research suggests that for soccer players engaged in extended intermittent exercise, consuming an isocaloric blend of HBCD and whey protein isolate — split between pre-exercise and half-time — may be a practical nutritional strategy to support late-game performance and reduce perceived effort. However, the study was conducted in a laboratory setting with a small sample of nine players, and the exercise was a simulated protocol rather than an actual match, so how these results translate to real competitive soccer requires further investigation.
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Song K, Lee H, Sung J, Baek J, Park S, Hyun K, et al.. (2026). Effects of Highly Branched Cyclic Dextrin-Based Carbohydrate and Protein Co-Ingestion on Endurance Capacity and Metabolic Response in Soccer Players: A Randomized Crossover Trial.. Nutrients. https://doi.org/10.3390/nu18172855