Olive Leaf Extract in Handball Players

NCT07371052 | Completed

• 1 other identifier: handball players
• Study Type: interventional
• Target: 18
• Locations: 1 country
• Sites: 1

Brief Summary

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.

Conditions

Handball Players

Outcome Measures

Primary Outcomes (6)

• 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 Outcomes (1)

• 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.

Study Arms (2)

Study group

EXPERIMENTAL

olive leaf extract supplemented

Dietary Supplement: Olive leaf extract

Control group

PLACEBO COMPARATOR

placebo capsule supplemented

Other: Placebo

Interventions

Olive leaf extract DIETARY_SUPPLEMENT

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

Study group

Placebo OTHER

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

Control group

Eligibility Criteria

• Age: 18 Years - 25 Years
• Sex: male
• Healthy Volunteers: No
• Age Groups: Adult (18-64)

You may qualify if:

• 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

You may not qualify if:

• 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

Sponsors & Collaborators

• Karabuk University: lead

Study Sites (1)

Karabuk University

Karabük, Central, 78050, Turkey (Türkiye)

Location

MeSH Terms

Interventions

olive leaf extract

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: TRIPLE
• Who Masked: PARTICIPANT, CARE PROVIDER, INVESTIGATOR
• Masking Details: double blind (participant investigator)
• Purpose: PREVENTION
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Dr. Research Assistant, Nutritients

Model Details: Parallel assigned

Study Record Dates

• First Submitted: January 15, 2026
• First Posted: January 27, 2026
• Study Start: January 1, 2025
• Primary Completion: January 15, 2025
• Study Completion: February 1, 2025
• Last Updated: January 27, 2026

Record last verified: 2026-01

Data Sharing

• IPD Sharing: Will not share

Locations

TU (1)