Olive Leaf Extract in Handball Players

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

Study Overview

• Status: Completed
• Conditions: Handball Players
• Intervention / Treatment: Dietary supplement: Olive leaf extract; Other: Placebo

• Study Type: Interventional
• Enrollment (Actual): 18
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Turkey (Türkiye)
  • Central
    • Karabük, Central, Turkey (Türkiye), 78050
      • Karabuk University

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: No

Description

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

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Prevention
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Triple

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Study group; olive leaf extract supplemented	Dietary supplement: Olive leaf extract; OLE supplement (500 mg, standardized to 25% oleuropein)
Placebo Comparator: Control group; placebo capsule supplemented	Other: Placebo; Sucrose capsules with the same color, scent, and size as OLE capsules.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Muscle Soreness	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.	Baseline, After intervention (two week later), After intervention (fourt week later)
Squat jump height	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.	Performance outcomes were assessed at baseline, week 2, and week 4 of the intervention period.
Peak anaerobic power	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.	baseline, week 2, and week 4.
Countermovement jump height	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.	Assessments were conducted at baseline, week 2, and week 4. Higher values indicate better explosive performance.
Mean anaerobic power	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.	Baseline, week 2, and week 4
Fatigue index	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.	Baseline, week 2, and week 4

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Sleep quality	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.	Total PSQI scores were recorded at baseline, week 2, and week 4 to evaluate changes in perceived sleep quality during the supplementation period.

Collaborators and Investigators

• Sponsor: Karabuk University

Study record dates

Study Major Dates

• Study Start (Actual): January 1, 2025
• Primary Completion (Actual): January 15, 2025
• Study Completion (Actual): February 1, 2025

Study Registration Dates

• First Submitted: January 15, 2026
• First Submitted That Met QC Criteria: January 22, 2026
• First Posted (Actual): January 27, 2026

Study Record Updates

• Last Update Posted (Actual): January 27, 2026
• Last Update Submitted That Met QC Criteria: January 22, 2026
• Last Verified: January 1, 2026

More Information

Terms related to this study

• Additional Relevant MeSH Terms: olive leaf extract
• Other Study ID Numbers: handball players

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

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