Metabolic, Respiratory, and Muscle Oxygenation Responses to Sub-maximal Eccentric and Concentric Isokinetic Exercise to Exhaustion (MUSOX-EX)

April 25, 2026 updated by: Vassilis Paschalis, National and Kapodistrian University of Athens

Responses to Sub-maximal Eccentric and Concentric Isokinetic Exercise to Exhaustion

This study aims to measure and compare the metabolic response during sub maximal eccentric and concentric isokinetic exercise performed to exhaustion. Fourteen healthy female participants in the early phase of the menstrual cycle will perform concentric exercise with one lower limb and eccentric exercise with the contralateral limb. The assignment of exercise mode to limb and the order of testing will be randomized. The exercise protocol will consist of repeated knee extensor contractions on an isokinetic dynamometer for 10 minutes at 40% of maximal torque, followed by exercise at 70% of maximal torque until exhaustion. Oxygen consumption and respiratory quotient and will be measured continuously throughout exercise using open-circuit spirometry. Muscle oxygenation will be measured also continuously using near infrared spectroscopy. Lactate and pH concentration will be measured at frequent time points during the exercise to exhaustion.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Completed

Conditions

Conditions

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Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Detailed Description

The purpose of this study is to investigate and compare the metabolic responses during sub maximal eccentric and concentric isokinetic exercise performed to exhaustion. Eccentric and concentric muscle actions differ in their physiological and metabolic demands, but their effects on respiratory parameters during fatiguing isokinetic exercise are not fully understood. This study is designed to examine whether these two contraction modes produce distinct metabolic responses under controlled exercise conditions.

Fourteen healthy female participants will be recruited and tested during the early phase of their menstrual cycle in order to reduce the possible influence of hormonal variation on physiological responses. A within-subject design will be used, with each participant completing both exercise conditions. One lower limb will perform concentric exercise and the contralateral lower limb will perform eccentric exercise. The limb allocation and the order of the two exercise conditions will be randomized.

All exercise testing will be conducted on an isokinetic dynamometer. The protocol will involve repeated contractions of the knee extensor muscles. Each trial will begin with 10 minutes of exercise at 40% of maximal torque. Following this initial stage, the intensity will be increased to 70% of maximal torque and maintained until volitional exhaustion is reached.

Oxygen consumption and respiratory quotient will be measured continuously throughout the exercise bout using open-circuit spirometry. Continuous monitoring of gas exchange during exercise will allow evaluation of substrate utilization and metabolic responses associated with each mode of contraction. Muscle oxygenation will be measured also continuously using near infrared spectroscopy. Lactate and pH concentration will be measured at frequent time points during the exercise to exhaustion.

The study is expected to provide further insight into the metabolic and respiratory differences between eccentric and concentric exercise performed under submaximal but fatiguing isokinetic conditions. The findings may have implications for exercise testing, training prescription, and rehabilitation settings in which eccentric and concentric muscle actions are used for different physiological purposes.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Actual)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
14

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • Greece
    • Attica
      • Athens, Attica, Greece, 17234
        • School of Physical Education and Sport Science

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

  • Adult

Accepts Healthy Volunteers

Yes

Description

Inclusion Criteria:

  • Physically active young females
  • No experience in activities involving significant resistance exercise components
  • No experience in muscle-damaging activities for at least 6-months prior to the study.

Exclusion Criteria:

  • Any musculoskeletal injuries in the lower limbs within the past 6 months
  • Use of contraceptives
  • Irregular menstrual cycles
  • Smoking
  • Consumption of protein and antioxidant supplements
  • Potential inflammatory conditions.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Basic Science
  • Allocation: Randomized
  • Interventional Model: Crossover Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Experimental: Isokinetic concentric exercise
The concentric isokinetic exercise will be consisted of 10 minutes at 40% of maximal torque followed by repetitions at an intensity of 70% of maximal torque until exhaustion.
Other: Sub maximal concentric exercise
Based on their maximal performance on isokinetic concentric muscle contractions, participants performed sub-maximal concentric knee extensor exercise on an isokinetic dynamometer. The protocol consists of 10 minutes exercise at 40% of maximal torque followed by exercise at 70% of maximal torque until exhaustion. The exercise protocol was continuous, which mean that no interval was adopted at any stage of the protocol.
Experimental: Isokinetic eccentric exercise
The eccentric isokinetic exercise will be consisted of 10 minutes at 40% of maximal torque followed by repetitions at an intensity of 70% of maximal torque until exhaustion.
Other: Sub maximal eccentric exercise
Based on their maximal performance on isokinetic eccentric muscle contractions, participants performed sub-maximal concentric knee extensor exercise on an isokinetic dynamometer. The protocol consists of 10 minutes exercise at 40% of maximal torque followed by exercise at 70% of maximal torque until exhaustion. The exercise protocol was continuous, which mean that no interval was adopted at any stage of the protocol.

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Oxygen consumption
Time Frame: From the first intervention to the last intervention 2 weeks
Oxygen consumption will be measured continuously using a open circuit chart during the whole duration of the isokinetic (either eccentric or concentric) exercise.
From the first intervention to the last intervention 2 weeks
Muscle oxygenation
Time Frame: From the first intervention to the last intervention 2 weeks
Muscle oxygenation will be measured continuously using a open circuit chart during the whole duration of the isokinetic (either eccentric or concentric) exercise.
From the first intervention to the last intervention 2 weeks
Duration of the isokinetic exercise
Time Frame: From the first intervention to the last intervention 2 weeks
The whole duration of both isokinetic concentric and eccentric exercise will be recored
From the first intervention to the last intervention 2 weeks

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Respiratory quotient
Time Frame: From the first intervention to the last intervention 2 weeks
Respiratory quotient will be measured continuously using a open circuit chart during the whole duration of the isokinetic (either eccentric or concentric) exercise.
From the first intervention to the last intervention 2 weeks
Lactate concentration
Time Frame: From the first intervention to the last intervention 2 weeks
Blood from fingertips will be collected periodically during the isokinetic exercise for both types of muscle contraction (concentric and eccentric)
From the first intervention to the last intervention 2 weeks
pH measurement
Time Frame: From the first intervention to the last intervention 2 weeks
Blood will be collected periodically during the isokinetic exercise for both types of muscle contraction (concentric and eccentric)
From the first intervention to the last intervention 2 weeks

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
National and Kapodistrian University of Athens

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
September 12, 2025

Primary Completion (Actual)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
January 18, 2026

Study Completion (Actual)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
March 28, 2026

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
April 17, 2026

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
April 17, 2026

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
April 23, 2026

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
April 30, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
April 25, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
April 1, 2026

More Information

Terms related to this study

Keywords

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • 1424/21-11-2022

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

IPD Plan Description

Individual participant data will not be made publicly available.

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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