Caffeinated Gum Use and Volleyball Performance

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

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.

Study Overview

• Status: Completed
• Conditions: Performance; Volleyball Players
• Intervention / Treatment: Dietary supplement: Single-dose caffeinated gum; Dietary supplement: Partial-dose caffeinated gum; Dietary supplement: Placebo gum

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.

• Study Type: Interventional
• Enrollment (Actual): 11
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Turkey (Türkiye)
  • Bornova
    • Izmir, Bornova, Turkey (Türkiye), 35040
      • Ege University, Faculty of Sport Sciences

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: Yes

Description

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.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Other
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: Double

Number of Arms

6

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Placebo, Single-Dose Caffeine, Partial-Dose Caffeine Arm Type: Experimental; 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.	Dietary supplement: Single-dose caffeinated 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.; Other Names: Caffeine gum; Caffeinated chewing gum; Dietary supplement: Partial-dose caffeinated 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.; Other Names: Caffeine gum; Caffeinated chewing gum; Dietary supplement: Placebo 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.; Other Names: Caffeine-free gum; Placebo chewing gum
Experimental: Placebo, Partial-Dose Caffeine, Single-Dose Caffeine; 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.	Dietary supplement: Single-dose caffeinated 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.; Other Names: Caffeine gum; Caffeinated chewing gum; Dietary supplement: Partial-dose caffeinated 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.; Other Names: Caffeine gum; Caffeinated chewing gum; Dietary supplement: Placebo 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.; Other Names: Caffeine-free gum; Placebo chewing gum
Experimental: Single-Dose Caffeine, Placebo, Partial-Dose Caffeine; 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.	Dietary supplement: Single-dose caffeinated 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.; Other Names: Caffeine gum; Caffeinated chewing gum; Dietary supplement: Partial-dose caffeinated 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.; Other Names: Caffeine gum; Caffeinated chewing gum; Dietary supplement: Placebo 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.; Other Names: Caffeine-free gum; Placebo chewing gum
Experimental: Single-Dose Caffeine, Partial-Dose Caffeine, Placebo; 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.	Dietary supplement: Single-dose caffeinated 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.; Other Names: Caffeine gum; Caffeinated chewing gum; Dietary supplement: Partial-dose caffeinated 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.; Other Names: Caffeine gum; Caffeinated chewing gum; Dietary supplement: Placebo 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.; Other Names: Caffeine-free gum; Placebo chewing gum
Experimental: Partial-Dose Caffeine, Placebo, Single-Dose Caffeine; 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.	Dietary supplement: Single-dose caffeinated 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.; Other Names: Caffeine gum; Caffeinated chewing gum; Dietary supplement: Partial-dose caffeinated 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.; Other Names: Caffeine gum; Caffeinated chewing gum; Dietary supplement: Placebo 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.; Other Names: Caffeine-free gum; Placebo chewing gum
Experimental: Partial-Dose Caffeine, Single-Dose Caffeine, Placebo; 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.	Dietary supplement: Single-dose caffeinated 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.; Other Names: Caffeine gum; Caffeinated chewing gum; Dietary supplement: Partial-dose caffeinated 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.; Other Names: Caffeine gum; Caffeinated chewing gum; Dietary supplement: Placebo 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.; Other Names: Caffeine-free gum; Placebo chewing gum

What is the study measuring?

Primary Outcome Measures

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

Secondary Outcome Measures

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

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Side effects	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.	Immediately after each experimental trial

Collaborators and Investigators

• Sponsor: Ege University

Study record dates

Study Major Dates

• Study Start (Actual): August 5, 2025
• Primary Completion (Actual): April 23, 2026
• Study Completion (Actual): April 23, 2026

Study Registration Dates

• First Submitted: May 11, 2026
• First Submitted That Met QC Criteria: May 15, 2026
• First Posted (Actual): May 19, 2026

Study Record Updates

• Last Update Posted (Actual): May 19, 2026
• Last Update Submitted That Met QC Criteria: May 15, 2026
• Last Verified: May 1, 2026

More Information

Terms related to this study

• Keywords: Caffeine; Athletic performance; Volleyball; Vertical jump; Caffeinated gum
• Other Study ID Numbers: EGE-25-9.1T-28

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO
• IPD Plan Description: Individual participant data will not be shared because the dataset contains participant-level performance and physiological data from a small group of elite female volleyball players, which may increase the risk of participant identification.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No