In 15 elite women volleyball players, 6 mg/kg caffeinated gum was tied to a smaller drop in block-jump power after exercise fatigue

What the research found

A randomized crossover was published on 9 November 2026. Jinghui Zhong, Jiyan Xu, and colleagues tested 15 elite women volleyball players. The abstract does not give age. They compared placebo gum with caffeinated gum at nominal doses of 3 mg/kg and 6 mg/kg, after a warm-up and again after a volleyball blocking protocol meant to bring on exercise fatigue. Jump scores fell after the protocol in every condition (p < 0.05). Block-jump peak power fell 13.9 percent with placebo and 6.9 percent with the 6 mg/kg gum. The adjusted comparison did not show that 6 mg/kg beat 3 mg/kg. Overall sequence time rose 18.4 percent with placebo, 6.4 percent with 3 mg/kg, and 3.0 percent with 6 mg/kg. Some countermovement and drop-jump measures, including drop-jump height and vertical stiffness, were better preserved with 6 mg/kg than placebo (p < 0.05). Players guessed they had caffeine on 0 percent of placebo visits, 53.3 percent of 3 mg/kg visits, and 80 percent of 6 mg/kg visits. Adverse effects were more common at 6 mg/kg. DOI 10.1080/15502783.2026.2749890. Not medical advice.

Evidence level: Clinical trial. This is among the stronger kinds of evidence, but one study rarely settles a question.

Read the original at Journal of the International Society of Sports Nutrition