Effects of Adding End-Range Isometric Holds to Isotonic Knee Extensor Training on Isokinetic Performance in Sedentary Adults

NCT07667543 | Completed

• 1 other identifier: 127742
• Study Type: interventional
• Target: 43
• Locations: 1 country
• Sites: 1

Brief Summary

The goal of this clinical trial is to learn if adding a short muscle hold (isometric contraction) to a standard leg-strengthening exercise improves knee muscle strength more than the standard exercise alone, in healthy adults who do not exercise regularly. The main question it aims to answer is: Does adding a 5-second hold at the end of each leg-extension exercise lead to greater gains in front-thigh muscle (quadriceps) strength than leg-extension exercise alone? Researchers will compare two exercise groups to see if the added muscle hold makes a difference: Group 1 will do leg-extension exercises with a 5-second hold added at the end of each repetition. Group 2 will do the same leg-extension exercises without the added hold. Participants will: Do leg-extension exercises 3 days a week for 8 weeks Have their thigh muscle strength tested before and after the program using a special exercise machine Have their thigh size measured before and after the program

Conditions

Quadriceps Muscle Strength; Isokinetic

Keywords

quadriceps muscle; isokinetic exercise; knee extensor strength; isometric contraction; resistance training

Outcome Measures

Primary Outcomes (1)

• Change in Quadriceps Femoris Isokinetic Peak Torque

  Quadriceps femoris isokinetic peak torque (PT, Nm) was measured bilaterally using a CSMI Humac Norm 2004 isokinetic dynamometer at angular velocities of 60°/second (5 maximal repetitions) and 180°/second (15 maximal repetitions).

  Baseline and 8 weeks

Secondary Outcomes (2)

• Change in Quadriceps Femoris 1-Repetition Maximum (1RM) Isotonic Strength

  Baseline and 8 weeks

• Change in Thigh Circumference

  Baseline and 8 weeks

Study Arms (2)

Isotonic + Isometric Hold Group

EXPERIMENTAL

Participants performed isotonic knee-extension exercise (2 sets of 10 repetitions at 60% of 1-repetition maximum) using a leg-extension machine, 3 days per week for 8 weeks, with weekly load progression (\~5%) and 60 seconds of rest between sets. At the end of each repetition, participants held the lifted weight for 5 seconds at 0° knee extension (isometric contraction) before returning to the starting position.

Other: Isotonic Exercise With Added Isometric Hold

Isotonic Only Group

ACTIVE COMPARATOR

Participants performed the same isotonic knee-extension exercise protocol (2 sets of 10 repetitions at 60% of 1-repetition maximum) using a leg-extension machine, 3 days per week for 8 weeks, with weekly load progression (\~5%) and 60 seconds of rest between sets, without the addition of an isometric hold at the end of each repetition.

Other: Isotonic Exercise Only

Interventions

Isotonic Exercise Only OTHER

Isotonic knee-extension exercise (2 sets of 10 repetitions at 60% of 1-repetition maximum) performed 3 days per week for 8 weeks, with weekly load progression (\~5%) and 60 seconds of rest between sets, without an added isometric hold.

Isotonic Only Group

Isotonic Exercise With Added Isometric Hold OTHER

Isotonic knee-extension exercise (2 sets of 10 repetitions at 60% of 1-repetition maximum) performed 3 days per week for 8 weeks, with weekly load progression (\~5%) and 60 seconds of rest between sets. Each repetition concluded with a 5-second isometric hold of the lifted weight at 0° knee extension.

Isotonic + Isometric Hold Group

Eligibility Criteria

• Age: 18 Years - 40 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64)

You may qualify if:

• Age 18-40 years
• Sedentary lifestyle (low physical activity level)
• Healthy individuals with no known knee-related disability

You may not qualify if:

• Musculoskeletal problems of the lower extremity
• History of lower extremity surgery or significant trauma
• Low back pain and/or lumbar region problems
• Cardiac complaints
• Neurological complaints
• Chronic systemic disease (e.g., diabetes mellitus, rheumatologic conditions)

Sponsors & Collaborators

• Yeditepe University: lead

Study Sites (1)

Sportomed | Physical Therapy and Rehabilitation Center

Istanbul, Bostancı/Kadıköy, 34744, Turkey (Türkiye)

Location

Study Officials

• Feyza Şule Hantal, PhD

  Yeditepe University

  STUDY DIRECTOR

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: SINGLE
• Who Masked: PARTICIPANT
• Purpose: TREATMENT
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Physiotherapist

Model Details: Participants were randomized to two parallel groups performing the same isotonic knee-extension protocol, with Group 1 adding a 5-second isometric hold at the end of each repetition and Group 2 performing the exercise without this addition.

Study Record Dates

• First Submitted: June 19, 2026
• First Posted: June 25, 2026
• Study Start: December 12, 2014
• Primary Completion: May 26, 2015
• Study Completion: July 6, 2015
• Last Updated: June 30, 2026

Record last verified: 2026-06

Locations

TU (1)