A cyclic-dextrin-and-whey drink improved a final endurance test compared with water in a small soccer simulation. It did not significantly outperform cyclic dextrin alone. The study is relevant to exercise fueling, but it does not prove that adding whey makes a carbohydrate drink better.
When a workout lasts long enough to make fueling matter, the comparison drink can change the story. Beating water is useful information. Beating a similarly caloric carbohydrate drink would answer a different question.
Three drinks, one demanding simulation
The 2026 Nutrients crossover trial enrolled ten male university soccer players; nine completed it. Each tested three beverages during an approximately two-hour treadmill soccer simulation, followed by a run to fatigue.
| Drink | Carbohydrate | Whey isolate |
|---|---|---|
| Water | 0 g | 0 g |
| Cyclic dextrin | 40 g | 0 g |
| Cyclic dextrin + whey | 32 g | 8 g |
Participants drank 250 mL before exercise and 250 mL at halftime. The two nutrient-containing drinks had similar calories. The combination increased time and distance in the final run compared with water, but not compared with carbohydrate alone. Gastrointestinal discomfort did not differ.
The result to keep in perspective
The study does not isolate a reliable performance advantage from adding protein. A statistically significant difference against water is not evidence of a significant difference against the carbohydrate condition.
It also swapped some carbohydrate for protein rather than simply adding protein to the same carbohydrate dose. That is a meaningful design choice: the experiment compared two beverage formulations, not “the identical drink, plus extra whey.”
With nine completers, a single-blind design, and a laboratory simulation, this is preliminary evidence. It cannot establish the ideal race-day recipe for every athlete, and it was not a HYROX trial or an actual soccer match.
What highly branched cyclic dextrin means
Highly branched cyclic dextrin, often abbreviated HBCD, is a carbohydrate ingredient used in sports drinks. Cluster Dextrin is the branded ingredient used in XWERKS Motion.
Earlier human research has examined its behavior in the stomach. A small study of ten volunteers compared gastric emptying of drinks containing HBCD and other carbohydrates. That is useful background on beverage formulation, but gastric emptying and exercise performance are separate outcomes.
For a practical ingredient comparison, see Cluster Dextrin versus other carbohydrates.
Where Motion and Grow fit
Motion provides 25 grams of carbohydrate and 3 grams of BCAAs per serving. BCAAs are not the same ingredient as the complete whey protein isolate used in this trial. Grow supplies whey isolate, but a Motion-and-Grow mixture was not tested.
That distinction prevents a common shortcut: a paper involving two ingredient categories does not validate every commercial product combination that contains them.
Should you put protein in your training drink?
This paper alone cannot answer that for you. Start by defining the problem: session duration, what you ate beforehand, fluid needs, and what your stomach tolerates. Trial a familiar plan in training before changing several variables on competition day.
If you want to evaluate a drink, keep the session and pre-workout meal similar, record how it feels, and avoid interpreting one unusually good workout as proof. Our intra-workout fueling guide provides a broader framework.
