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NCT Number: NCT07113405

Influence of Tea Extract on Maximal Voluntary Knee Contraction Following Downhill Jogging

In this research project, we want to investigate whether the combined intake of proteins and tea extract has an influence on muscle regeneration compared to the sole intake of proteins or a placebo product. In the study, you will be randomly assigned to one of 3 groups. Neither the research group nor you will know which group you are assigned to. The study lasts 5 days for you as a participant. During these 5 days you will have to attend a total of 5 appointments in our laboratory. The groups differ only in the intake of the regeneration product, otherwise all measurements and appointments are identical. You will jog downhill for 30 minutes on the first day in order to strain your muscles. In order to be able to draw conclusions about the regeneration of your muscles, we will carry out the following measurements on all 5 days: Blood sampling at the fingertip, ultrasound of the thigh muscle, pain tolerance of the thigh muscle, strength tests of the thigh muscle, muscle function of the thigh muscle and jumping performance.

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Key information

Conditions

Muscle Recovery

Age range

18 year–40 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

University of Fribourg

Fribourg, Canton of Fribourg, 1700, Switzerland

Location status: Recruiting

Location contact

Sven Egger, Dr.

CONTACT

[email protected]

+41 26 300 72 85

Who can participate

Healthy volunteers accepted: Yes

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

Inclusion criteria

  • Signed written informed consent
  • Aged between 18-40 years
  • Healthy subjects

Exclusion criteria

  • Any type of food allergy (e.g. nuts)
  • Health-related problems according to the "Physical Activity Readiness Questionnaire (PAR-Q)
  • Current injury of the lower extremities
  • Serious clinical back pain or current back injuries
  • Orthopedic disorders
  • Cardiovascular diseases
  • Current Intake of blood-thinning medication
  • Current Intake of anti-inflammatory medication

Treatment and study plan

Protein and tea extract

Dietary Supplement

Participants in this group will receive 4 times a recovery drink containing protein and tea extract.

Protein

Dietary Supplement

Participants of this group will receive ten times a recovery drink containing only protein without tea extract.

Placebo

Dietary Supplement

Participants of this group will receive 10 times a placebo containing no protein nor tea extract.

Primary outcomes

  1. Change in maximum knee extension force immediately after training-induced muscle damage and 24, 48, 72, and 96 hours thereafter compared to baseline.

    Time frame: 5 days

    The maximal force is measured in Nm while the participant is seated on an isokinetic device.

  2. Change in jump performance immediately after training-induced muscle damage and 24, 48, 72, and 96 hours thereafter compared to baseline.

    Time frame: 5 days

    The jump performance is measured in cm while the participant are performing counter movement jumps.

  3. Change in perceived pain immediately after training-induced muscle damage and 24, 48, 72, and 96 hours thereafter compared to baseline.

    Time frame: 5 days

    Perceived pain is measured in Pa while the participant is seated on the isokinetic device. The measurement point is on vastus medialis muscle.

  4. Change in muscle thickness immediately after training-induced muscle damage and 24, 48, 72, and 96 hours thereafter compared to baseline.

    Time frame: 5 days

    Muscle thickness is measured with b-mode ultrasound in mm while the participant is sitting on the isokinetic device. The measurement point is on the vastus medialis muscle.

  5. Change in creatine kinase levels immediately after exercise-induced muscle damage and 24, 48, 72, and 96 hours thereafter compared to baseline.

    Time frame: 5 days

    Creatine kinase is measured in U/L and determined using a capillary finger blood sample of 0.25 ml.

Study contacts

Contact information is provided by the study sponsor or research team.

Benedikt Lauber, PD Dr.

CONTACT

[email protected]

+41 26 300 72 86

Sven Egger, Dr.

CONTACT

[email protected]

+41 26 300 72 85

Sponsors and collaborators

Lead sponsor

University of Fribourg

Other

Registry information

Official study title

The Influence of Tea Extract on Maximal Voluntary Knee Contraction After 30 Minutes of Downhill Jogging: a Randomized, Double-blind, Placebo-controlled Study

Acronym: ITMVC-DJ

Important dates

Study start
2025
Primary completion
2026
Study completion
2026
First posted
Aug 8, 2025
Registry last updated
May 4, 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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