Caffeinated Gum Use and Volleyball Performance

NCT07597265 — Not applicable, Completed, 11 participants, Ege University

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Acute Effects of Caffeinated Gum Use on Volleyball Performance: A Randomized, Placebo-Controlled Crossover Trial

Registry	NCT07597265
Status	Completed
Phase	Not applicable
Study type	Interventional; randomized, crossover, masking: double, other
Enrollment	11 (Actual)
Sponsor	Ege University (Other)
Conditions	Volleyball Players, Performance
Interventions	Single-dose caffeinated gum, Partial-dose caffeinated gum, Placebo gum (Dietary supplement)
Dates	start 2025-08-05, primary completion 2026-04-23, completion 2026-04-23, first posted 2026-05-19, last updated 2026-05-19
Locations	1 site in Turkey (Türkiye)

-Summary

This study examined the acute effects of caffeinated chewing gum on volleyball performance in trained female volleyball players. Caffeine is commonly used by athletes to improve performance, but less is known about whether caffeinated gum is useful during volleyball-specific activity.

Participants completed three testing sessions in a randomized crossover design. In one session, they chewed placebo gum. In another session, they chewed caffeinated gum containing a single 300 mg dose of caffeine. In the third session, they received the same total amount of caffeine as three separate 100 mg doses given at 30-minute intervals.

The study assessed volleyball-specific skill performance, including attack, block, and defense efficiency, during a volleyball-specific skill game. Vertical jump height, heart rate, perceived exertion, side effects, and condition guessing were also recorded.

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+Detailed description

This randomized, placebo-controlled, crossover study investigated whether the pattern of caffeinated gum administration affects volleyball-specific performance in trained female volleyball players. Participants completed one familiarization session and three experimental sessions separated by one week. The experimental conditions were placebo gum, single-dose caffeinated gum, and partial-dose caffeinated gum.

In the single-dose condition, participants chewed three pieces of caffeinated gum containing a total of 300 mg caffeine for 5 minutes. In the partial-dose condition, participants chewed one piece of caffeinated gum containing 100 mg caffeine at three different time points, with 30-minute intervals between doses. In the placebo condition, participants chewed caffeine-free gum for 5 minutes.

Each testing session included volleyball-specific activities and a 30-minute volleyball-specific skill game. Attack, block, and defense efficiency were assessed using video recordings and Data Volley software. Vertical jump height was measured before and after the volleyball-specific activity. Heart rate was recorded during the session, and rating of perceived exertion was assessed before and after the session. Participants were also asked to report side effects and to guess which condition they had received after each session.

+Arms and interventions

Arm	Type	Interventions	Description
Placebo, Single-Dose Caffeine, Partial-Dose Caffeine Arm Type: Experimental	Experimental	Dietary Supplement: Single-dose caffeinated gum; Dietary Supplement: Partial-dose caffeinated gum; Dietary Supplement: Placebo gum	Participants received placebo gum in the first session, single-dose caffeinated gum in the second session, and partial-dose caffeinated gum in the third session. Sessions were separated by one week.
Placebo, Partial-Dose Caffeine, Single-Dose Caffeine	Experimental	Dietary Supplement: Single-dose caffeinated gum; Dietary Supplement: Partial-dose caffeinated gum; Dietary Supplement: Placebo gum	Participants received placebo gum in the first session, partial-dose caffeinated gum in the second session, and single-dose caffeinated gum in the third session. Sessions were separated by one week.
Single-Dose Caffeine, Placebo, Partial-Dose Caffeine	Experimental	Dietary Supplement: Single-dose caffeinated gum; Dietary Supplement: Partial-dose caffeinated gum; Dietary Supplement: Placebo gum	Participants received single-dose caffeinated gum in the first session, placebo gum in the second session, and partial-dose caffeinated gum in the third session. Sessions were separated by one week.
Single-Dose Caffeine, Partial-Dose Caffeine, Placebo	Experimental	Dietary Supplement: Single-dose caffeinated gum; Dietary Supplement: Partial-dose caffeinated gum; Dietary Supplement: Placebo gum	Participants received single-dose caffeinated gum in the first session, partial-dose caffeinated gum in the second session, and placebo gum in the third session. Sessions were separated by one week.
Partial-Dose Caffeine, Placebo, Single-Dose Caffeine	Experimental	Dietary Supplement: Single-dose caffeinated gum; Dietary Supplement: Partial-dose caffeinated gum; Dietary Supplement: Placebo gum	Participants received partial-dose caffeinated gum in the first session, placebo gum in the second session, and single-dose caffeinated gum in the third session. Sessions were separated by one week.
Partial-Dose Caffeine, Single-Dose Caffeine, Placebo	Experimental	Dietary Supplement: Single-dose caffeinated gum; Dietary Supplement: Partial-dose caffeinated gum; Dietary Supplement: Placebo gum	Participants received partial-dose caffeinated gum in the first session, single-dose caffeinated gum in the second session, and placebo gum in the third session. Sessions were separated by one week.

Single-dose caffeinated gum (Dietary supplement), also known as Caffeine gum, Caffeinated chewing gum: Participants chewed three pieces of caffeinated gum containing 100 mg caffeine per piece, providing a total dose of 300 mg caffeine. The gum was chewed for 5 minutes and then discarded.
Partial-dose caffeinated gum (Dietary supplement), also known as Caffeine gum, Caffeinated chewing gum: Participants received three separate pieces of caffeinated gum containing 100 mg caffeine per piece. One piece was chewed for 5 minutes at each administration time point, with doses given at 30-minute intervals, providing a total dose of 300 mg caffeine.
Placebo gum (Dietary supplement), also known as Caffeine-free gum, Placebo chewing gum: Participants chewed caffeine-free placebo gum for 5 minutes. The placebo gum was selected to be similar in shape and color to the caffeinated gum.

+Outcome measures

Primary outcomes

Attack efficiency [During the 30-minute volleyball-specific skill game in each experimental trial]: Attack efficiency was assessed during a 30-minute volleyball-specific skill game using video recordings and Data Volley software. Values were expressed as percentages.
Block efficiency [During the 30-minute volleyball-specific skill game in each experimental trial]: Block efficiency was assessed during a 30-minute volleyball-specific skill game using video recordings and Data Volley software. Values were expressed as percentages.
Defense efficiency [During the 30-minute volleyball-specific skill game in each experimental trial]: Defense efficiency was assessed during a 30-minute volleyball-specific skill game using video recordings and Data Volley software. Values were expressed as percentages.

Secondary outcomes

Change in vertical jump height [From immediately before to immediately after each experimental trial]: Vertical jump height was measured before and after each experimental testing session using a photoelectric cell system. Values were expressed in centimeters.
Heart rate [Continuously during each experimental trial]: Heart rate was recorded during each experimental testing session using a telemetric heart rate monitoring system. Values were expressed as beats per minute.
Change in rating of perceived exertion [From immediately before to immediately after each experimental trial]: Rating of perceived exertion was assessed before and after each experimental testing session using a 0-10 Borg scale.

Other outcomes

Side effects [Immediately after each experimental trial]: Participants were asked after each experimental testing session whether they experienced any side effects or discomfort related to the gum intervention. Reported responses were recorded descriptively.

+Eligibility

Sex: Female, ages: 18 Years to 35 Years, accepts healthy volunteers

Inclusion Criteria:

* Female volleyball players aged 18 to 35 years.
* Apparently healthy.
* Daily caffeine intake ≤300 mg.
* Minimum of 5 years of regular volleyball training experience.
* Training for at least 120 minutes at least 3 days per week.
* Competing in national or international volleyball matches.
* Provided written informed consent before participation.

Exclusion Criteria:

* Serious injury or trauma within the past 6 months that could affect volleyball performance.
* Illness or inability to continue the study protocol during the research period.
* Development of side effects during caffeinated gum administration that prevented continuation.
* Regular alcohol or drug use that could affect the study outcomes.

+Locations (1)

Facility	City	Country	Status
Ege University, Faculty of Sport Sciences	Izmir, Bornova	Turkey (Türkiye)

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