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Completed

NCT Number: NCT07597265

Caffeinated Gum Use and Volleyball Performance

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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Key information

Conditions

Volleyball Players Performance

Age range

18 year–35 year

Sex eligibility

Female

Study type

Interventional

Phase

Not applicable

Primary location

Ege University, Faculty of Sport Sciences

Izmir, Bornova, 35040, Turkey (Türkiye)

About this study

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.

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

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.

Treatment and study plan

Single-dose caffeinated gum

Dietary Supplement

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

Partial-dose caffeinated gum

Dietary Supplement

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

Placebo gum

Dietary Supplement

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

Primary outcomes

  1. Attack efficiency

    Time frame: 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.

  2. Block efficiency

    Time frame: 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.

  3. Defense efficiency

    Time frame: 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

  1. Change in vertical jump height

    Time frame: 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.

  2. Heart rate

    Time frame: 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.

  3. Change in rating of perceived exertion

    Time frame: 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

  1. Side effects

    Time frame: 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.

Sponsors and collaborators

Lead sponsor

Ege University

Other

Registry information

Official study title

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

Important dates

Study start
2025
Primary completion
2026
Study completion
2026
First posted
May 19, 2026
Registry last updated
May 19, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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