Effect of Low-Dose Caffeine on Performance in Elite Sitting Volleyball Players

NCT07056231 | Completed

• 1 other identifier: 2025/91
• Study Type: interventional
• Target: 13
• Locations: 1 country
• Sites: 1

Brief Summary

Background: Sitting volleyball is a sport that relies primarily on upper body strength and anaerobic capacity. In critical in-game skills such as serve and spike, factors such as speed-endurance time and impact power play a decisive role in performance. There are limited studies in the literature examining the effects of low-dose caffeine consumption on these skills. The effects of ergogenic supplements in Paralympic sports have not been sufficiently investigated, and the potential benefits of caffeine on serve and spike performance in sitting volleyball players remain unclear. Purpose: The main purpose of this research was to determine the effects of low-dose caffeine (3 mg/kg) consumption on the serve speed, spike speed and Speed-Endurance performances of elite-level sitting volleyball players. Method: The study was designed using a randomized, double-blind, balanced, and crossover experimental design. 13 elite male athletes from the 2024 Paravolley European Champion Sitting Volleyball Men's National Team participated in the study. Participants were evaluated for serve speed, spike speed, and speed-endurance performances in both 3 mg/kg caffeine (CAF) and placebo (PLA) conditions.

Conditions

Caffeine; Physical Endurance; Muscle Strength; Paralympic Athletes

Outcome Measures

Primary Outcomes (3)

• Serve Speed

  Serve speed will be assessed using a calibrated radar device to record peak velocity of each participant's volleyball serve.

  After 60 minutes ingestion of the supplement on test day (CAF and PLA)

• Spike Speed

  Maximum spike speed will be measured in kilometers per hour (km/h) using a radar gun during a standardized spike task conducted after supplementation in each condition.

  After 60 minutes ingestion of the supplement on test day (CAF and PLA)

• Speed-Endurance

  The number of maximal shuttle runs completed in a repeated sprint ability (RSA) test protocol will be recorded to assess speed-endurance capacity.

  After 60 minutes ingestion of the supplement on test day (CAF and PLA)

Study Arms (2)

Low-Dose Caffeine Arm

EXPERIMENTAL

Participants receive a single oral dose of caffeine (3 mg/kg) during the first session and a placebo in the second session. There is a washout period of at least 48 hours between sessions.

Dietary Supplement: Caffeine; Dietary Supplement: Placebo

Placebo Arm

EXPERIMENTAL

Participants receive a placebo during the first session and a single oral dose of caffeine (3 mg/kg) in the second session. There is a washout period of at least 48 hours between sessions.

Dietary Supplement: Caffeine; Dietary Supplement: Placebo

Interventions

Caffeine DIETARY_SUPPLEMENT

A single oral dose of 3 mg of caffeine per kilogram of body weight form approximately 60 minutes before performance testing. Supplied by Oxford Vitality, ISO-certified.

Low-Dose Caffeine Arm; Placebo Arm

Placebo DIETARY_SUPPLEMENT

polydextrose used as Placebo

Low-Dose Caffeine Arm; Placebo Arm

Eligibility Criteria

• Age: 18 Years - 35 Years
• Sex: male
• Healthy Volunteers: No
• Age Groups: Adult (18-64)

You may qualify if:

• Male sitting volleyball players aged between 18 and 40
• Member of the 2024 National Sitting Volleyball Team
• At least 3 years of competitive playing experience
• No caffeine consumption 48 hours prior to testing
• Provided informed consent to participate

You may not qualify if:

• Known cardiovascular, neurological, or metabolic disorders
• Current use of medications that may affect caffeine metabolism
• Allergy or sensitivity to caffeine
• Use of performance-enhancing substances within the last month

Sponsors & Collaborators

• Ulaç Can YILDIRIM: lead

Study Sites (1)

Karamanoğlu Mehmetbey University

Karaman, Central, 695002, Turkey (Türkiye)

Location

Related Publications (1)

• Diedhiou AB, Erkan D, Guler M, Sar H, Karakulak I, Eyuboglu E, Gundem MC, Karayigit R, Tuncer SY, Yildirim UC. The effect of low dose caffeine powder supplementation on serve speed, spike speed, and speed-endurance in elite sitting volleyball players: a randomized double-blind crossover study. BMC Sports Sci Med Rehabil. 2025 Nov 6;17(1):320. doi: 10.1186/s13102-025-01408-8.

  PMID: 41199325 DERIVED

MeSH Terms

Interventions

Caffeine

Intervention Hierarchy (Ancestors)

Xanthines; Alkaloids; Heterocyclic Compounds; Purinones; Purines; Heterocyclic Compounds, 2-Ring; Heterocyclic Compounds, Fused-Ring

Study Officials

• Ulas C Yildirim

  sinop university faculty of sport sciences

  STUDY CHAIR

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: QUADRUPLE
• Who Masked: PARTICIPANT, CARE PROVIDER, INVESTIGATOR, OUTCOMES ASSESSOR
• Purpose: BASIC SCIENCE
• Intervention Model: CROSSOVER
• Sponsor Type: OTHER
• Responsible Party: SPONSOR INVESTIGATOR
• PI Title: Assoc. Prof.

Study Record Dates

• First Submitted: June 21, 2025
• First Posted: July 9, 2025
• Study Start: March 5, 2025
• Primary Completion: March 11, 2025
• Study Completion: March 12, 2025
• Last Updated: July 9, 2025

Record last verified: 2025-06

Data Sharing

• IPD Sharing: Will not share

Locations

TU (1)