Volleyball PlayersNCT07597265
Caffeinated Gum Use and Volleyball Performance
A study testing Single-dose caffeinated gum and Partial-dose caffeinated gum in people with Volleyball Players and Performance, run by Ege University at 1 site in Turkey (Türkiye).
Trial 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. Read more about this study
- Who is it for?
- Ages 18 to 35 years, women onlyHealthy volunteers can take part
- Conditions the study is for
- Volleyball Players, Performance
- What is being tested?
- Single-dose caffeinated gum and Partial-dose caffeinated gum
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 11 participants
- Where
- 1 siteTurkey (Türkiye)
- Study dates
- 5 Aug 2025to 23 Apr 2026
- Phase
- Interventional
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 35 years
- Women only
- Healthy volunteers accepted
- Adult
Who may be able to join
- 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.
Who cannot join
- 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.
Trial locations and contacts
1 site in 1 country.
Turkey (Türkiye)1 site
Ege University, Faculty of Sport Sciences
Izmir, Bornova, 35040
About this study
Official title: 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.
Read the 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.
- Conditions
- Volleyball Players, Performance
- Being tested
- Single-dose caffeinated gum, Partial-dose caffeinated gum, Placebo gum
- Keywords
- Caffeine, Caffeinated gum, Volleyball, Athletic performance, Vertical jump
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Single-dose caffeinated gumDietary supplement
Also called 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 gumDietary supplement
Also called 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 gumDietary supplement
Also called 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.
| Study group | Role | What they receive |
|---|---|---|
| Placebo, Single-Dose Caffeine, Partial-Dose Caffeine Arm Type: Experimental | 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. Receives: Dietary Supplement: Single-dose caffeinated gum; Dietary Supplement: Partial-dose caffeinated gum; Dietary Supplement: Placebo gum |
| Placebo, Partial-Dose Caffeine, Single-Dose Caffeine | Experimental | 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. Receives: Dietary Supplement: Single-dose caffeinated gum; Dietary Supplement: Partial-dose caffeinated gum; Dietary Supplement: Placebo gum |
| Single-Dose Caffeine, Placebo, Partial-Dose Caffeine | Experimental | 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. Receives: Dietary Supplement: Single-dose caffeinated gum; Dietary Supplement: Partial-dose caffeinated gum; Dietary Supplement: Placebo gum |
| Single-Dose Caffeine, Partial-Dose Caffeine, Placebo | Experimental | 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. Receives: Dietary Supplement: Single-dose caffeinated gum; Dietary Supplement: Partial-dose caffeinated gum; Dietary Supplement: Placebo gum |
| Partial-Dose Caffeine, Placebo, Single-Dose Caffeine | Experimental | 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. Receives: Dietary Supplement: Single-dose caffeinated gum; Dietary Supplement: Partial-dose caffeinated gum; Dietary Supplement: Placebo gum |
| Partial-Dose Caffeine, Single-Dose Caffeine, Placebo | Experimental | 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. Receives: Dietary Supplement: Single-dose caffeinated gum; Dietary Supplement: Partial-dose caffeinated gum; Dietary Supplement: Placebo gum |
What is being measured
The primary outcome is the main question the study is designed to answer.
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.
Measured: 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.
Measured: 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.
Measured: During the 30-minute volleyball-specific skill game in each experimental trial
Secondary outcomes (3)
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.
Measured: 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.
Measured: 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.
Measured: From immediately before to immediately after each experimental trial
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted19 May 2026
- Study start5 Aug 2025
- Primary completion23 Apr 2026
- Study completion23 Apr 2026
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Volleyball PlayersStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Other
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- Double blind
- Who is masked
- Participant, Outcomes assessor
- Enrolment
- 11 participants (actual)
Sponsor and investigators
- Lead sponsor
- Ege University
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Gülbin Rudarlı, Ege University
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07597265
- Sponsor's protocol ID
- EGE-25-9.1T-28
- Status last verified
- May 2026
- First submitted
- 11 May 2026
- Last updated
- 19 May 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No: 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.
Study at a glance
From the registry record, last updated by the sponsor on 19 May 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Acute Effects of Caffeinated Gum Use on Volleyball Performance: A Randomized, Placebo-Controlled Crossover Trial
- ClinicalTrials.gov ID
- NCT07597265
- Acronym / sponsor ID
- EGE-25-9.1T-28
- Conditions
- Volleyball Players, Performance
- Keywords
- Caffeine, Caffeinated gum, Volleyball, Athletic performance, Vertical jump
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 11 participants (actual)
- Lead sponsor
- Ege UniversityUniversity, hospital or other
- Study start
- 5 Aug 2025 (actual)
- Primary completion
- 23 Apr 2026 (actual)
- Study completion
- 23 Apr 2026 (actual)
- First posted
- 19 May 2026 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
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.
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 design
- Primary purpose
- Other
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- Double blind (participant, outcomes assessor)
- Number of arms
- 6
| Arm | Type | Receives |
|---|---|---|
| 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 gumParticipants 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 gumParticipants 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 gumParticipants 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 gumParticipants 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 gumParticipants 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 gumParticipants 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. |
Who may qualify
- Ages
- 18 to 35 years
- Sex
- Female only
- Healthy volunteers
- Accepted
- Age groups
- Adult
Key inclusion criteria (7 listed)
- 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.
Key exclusion criteria (4 listed)
- 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.
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Single-dose caffeinated gumAlso: Caffeine gum, Caffeinated chewing gumParticipants 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. | Dietary supplement | Partial-Dose Caffeine, Placebo, Single-Dose Caffeine, Partial-Dose Caffeine, Single-Dose Caffeine, Placebo, Placebo, Partial-Dose Caffeine, Single-Dose Caffeine, Placebo, Single-Dose Caffeine, Partial-Dose Caffeine Arm Type: Experimental, Single-Dose Caffeine, Partial-Dose Caffeine, Placebo, Single-Dose Caffeine, Placebo, Partial-Dose Caffeine |
| Partial-dose caffeinated gumAlso: Caffeine gum, Caffeinated chewing gumParticipants 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. | Dietary supplement | Partial-Dose Caffeine, Placebo, Single-Dose Caffeine, Partial-Dose Caffeine, Single-Dose Caffeine, Placebo, Placebo, Partial-Dose Caffeine, Single-Dose Caffeine, Placebo, Single-Dose Caffeine, Partial-Dose Caffeine Arm Type: Experimental, Single-Dose Caffeine, Partial-Dose Caffeine, Placebo, Single-Dose Caffeine, Placebo, Partial-Dose Caffeine |
| Placebo gumAlso: Caffeine-free gum, Placebo chewing gumParticipants chewed caffeine-free placebo gum for 5 minutes. The placebo gum was selected to be similar in shape and color to the caffeinated gum. | Dietary supplement | Partial-Dose Caffeine, Placebo, Single-Dose Caffeine, Partial-Dose Caffeine, Single-Dose Caffeine, Placebo, Placebo, Partial-Dose Caffeine, Single-Dose Caffeine, Placebo, Single-Dose Caffeine, Partial-Dose Caffeine Arm Type: Experimental, Single-Dose Caffeine, Partial-Dose Caffeine, Placebo, Single-Dose Caffeine, Placebo, Partial-Dose Caffeine |
Primary outcome
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.
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.
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.
3 secondary outcomes
Change in vertical jump height
Time frame: From immediately before to immediately after each experimental trial
Heart rate
Time frame: Continuously during each experimental trial
Change in rating of perceived exertion
Time frame: From immediately before to immediately after each experimental trial
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 19 May 2026.
- Individual participant dataSharing planned: No. 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.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
The record lists no contact. Use the official record to reach the sponsor.
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Single-dose caffeinated gum and Partial-dose caffeinated gum in people with Volleyball Players and Performance, run by Ege University at 1 site in Turkey (Türkiye).
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 7 inclusion and 4 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 19 May 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Turkey (Türkiye). Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Attack efficiency (time frame: During the 30-minute volleyball-specific skill game in each experimental trial). The study lists 3 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 19 May 2026; AzTrials last refreshed its copy on 29 Oct 2026.