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

NCT07548333 | Completed

• 1 other identifier: 1424/21-11-2022
• Study Type: interventional
• Target: 14
• Locations: 1 country
• Sites: 1

Brief Summary

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.

Conditions

Eccentric Exercise; Isokinetic Test

Keywords

Eccentric exercise; Concentric exercise; oxygen consumption; muscle oxygenation

Outcome Measures

Primary Outcomes (3)

• Oxygen consumption

  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

  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

  The whole duration of both isokinetic concentric and eccentric exercise will be recored

  From the first intervention to the last intervention 2 weeks

Secondary Outcomes (3)

• Respiratory quotient

  From the first intervention to the last intervention 2 weeks

• Lactate concentration

  From the first intervention to the last intervention 2 weeks

• pH measurement

  From the first intervention to the last intervention 2 weeks

Study Arms (2)

Isokinetic concentric exercise

EXPERIMENTAL

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

Isokinetic eccentric exercise

EXPERIMENTAL

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

Interventions

Sub maximal concentric exercise OTHER

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.

Isokinetic concentric exercise

Sub maximal eccentric exercise OTHER

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.

Isokinetic eccentric exercise

Eligibility Criteria

• Age: 18 Years - 30 Years
• Sex: female
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64)

You may qualify if:

• 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.

You may not qualify if:

• 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.

Sponsors & Collaborators

• National and Kapodistrian University of Athens: lead

Study Sites (1)

School of Physical Education and Sport Science

Athens, Attica, 17234, Greece

Location

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: NONE
• Purpose: BASIC SCIENCE
• Intervention Model: CROSSOVER
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Associate Professor

Model Details: Each participant will complete 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.

Study Record Dates

• First Submitted: April 17, 2026
• First Posted: April 23, 2026
• Study Start: September 12, 2025
• Primary Completion: January 18, 2026
• Study Completion: March 28, 2026
• Last Updated: April 30, 2026

Record last verified: 2026-04

Data Sharing

• IPD Sharing: Will not share

Locations

GR (1)