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Completed

NCT Number: NCT07371052

Olive Leaf Extract in Handball Players

Olive leaf extract (OLE) is a natural supplement rich in phenolic compounds, especially oleuropein, which has antioxidant properties that may support recovery after physical exercise. While OLE has been studied for various health-related effects, its potential impact on exercise recovery and performance in elite athletes remains unclear.

This randomized, double-blind, placebo-controlled study was designed to evaluate the effects of four weeks of OLE supplementation on physical performance, sleep quality, and post-exercise muscle soreness in elite male handball players aged 18 to 25 years. Participants were randomly assigned to receive either a daily OLE supplement (500 mg, standardized to 25% oleuropein) or a placebo for four weeks. Physical performance, sleep quality, and muscle soreness were assessed at baseline, during the intervention, and at the end of the study period. Muscle soreness was additionally evaluated at 12 and 24 hours following exercise sessions.

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Key information

Conditions

Handball Players

Age range

18 year–25 year

Sex eligibility

Male

Study type

Interventional

Phase

Not applicable

Primary location

Karabuk University

Karabük, Central, 78050, Turkey (Türkiye)

Who can participate

Healthy volunteers accepted: No

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

Inclusion criteria

  • Male elite handball players aged 18 years or older
  • Free from any diagnosed chronic disease, as determined by medical history
  • Not following a calorie-restricted diet within the previous six months
  • No use of nutritional supplements within the previous six months

Exclusion criteria

  • Age under 18 years
  • Smoking or alcohol consumption
  • Presence of any diagnosed chronic disease
  • Adherence to a regular calorie-restricted diet within the previous six months
  • Use of nutritional supplements during the previous six months

Treatment and study plan

Olive leaf extract

Dietary Supplement

OLE supplement (500 mg, standardized to 25% oleuropein)

Placebo

Other

Sucrose capsules with the same color, scent, and size as OLE capsules.

Primary outcomes

  1. Muscle Soreness

    Time frame: Baseline, After intervention (two week later), After intervention (fourt week later)

    The severity of muscle soreness will be assessed using the Visual Analog Scale (VAS). Patients choose the appropriate score between 0 and 10. Higher scores indicate higher muscle soreness levels.

  2. Squat jump height

    Time frame: Performance outcomes were assessed at baseline, week 2, and week 4 of the intervention period.

    Lower-body explosive performance was assessed using the squat jump test. Jump height was measured in centimeters (cm) with higher values indicating better explosive performance.

  3. Peak anaerobic power

    Time frame: baseline, week 2, and week 4.

    Peak anaerobic power was assessed using the Wingate anaerobic test. Peak power output was recorded in watts (W) during the 30-second maximal cycling test. Higher values indicate greater anaerobic power.

  4. Countermovement jump height

    Time frame: Assessments were conducted at baseline, week 2, and week 4. Higher values indicate better explosive performance.

    Lower-body explosive performance was assessed using the countermovement jump test. Jump height was measured in centimeters (cm) with higher values indicating better explosive performance.

  5. Mean anaerobic power

    Time frame: Baseline, week 2, and week 4

    Mean anaerobic power was assessed using the Wingate anaerobic test. Mean power output was calculated as the average power produced over the 30-second test and recorded in watts (W). Higher values indicate better anaerobic capacity.

  6. Fatigue index

    Time frame: Baseline, week 2, and week 4

    Fatigue index was assessed using the Wingate anaerobic test and calculated as the percentage decline in power output from peak to minimum power during the 30-second test. Higher values indicate greater fatigue.

Secondary outcomes

  1. Sleep quality

    Time frame: Total PSQI scores were recorded at baseline, week 2, and week 4 to evaluate changes in perceived sleep quality during the supplementation period.

    Sleep quality was assessed using the Pittsburgh Sleep Quality Index (PSQI) total score. The PSQI is a validated self-reported questionnaire consisting of 19 items, yielding a global score ranging from 0 to 21, with higher scores indicating poorer sleep quality.

Sponsors and collaborators

Lead sponsor

Karabuk University

Other

Registry information

Official study title

Effects of Short-Term Olive Leaf Extract Supplementation in Elite Male Handball Players

Important dates

Study start
2025
Primary completion
2025
Study completion
2025
First posted
Jan 27, 2026
Registry last updated
Jan 27, 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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