Quadriceps Muscle StrengthNCT07667543
Effects of Adding End-Range Isometric Holds to Isotonic Knee Extensor Training on Isokinetic Performance in Sedentary Adults
A study testing Isotonic Exercise With Added Isometric Hold and Isotonic Exercise Only in people with Quadriceps Muscle Strength and Isokinetic, run by Yeditepe University at 1 site in Turkey (Türkiye).
Trial 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. Read more about this study
- Who is it for?
- Ages 18 to 40 yearsHealthy volunteers can take part
- Conditions the study is for
- Quadriceps Muscle Strength, Isokinetic
- What is being tested?
- Isotonic Exercise With Added Isometric Hold and Isotonic Exercise Only
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 43 participants
- Where
- 1 siteTurkey (Türkiye)
- Study dates
- 12 Dec 2014to 6 Jul 2015
- Phase
- Interventional
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 40 years
- All sexes
- Healthy volunteers accepted
- Adult
Who may be able to join
- Age 18-40 years
- Sedentary lifestyle (low physical activity level)
- Healthy individuals with no known knee-related disability
Who cannot join
- 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)
Trial locations and contacts
1 site in 1 country.
Turkey (Türkiye)1 site
Sportomed | Physical Therapy and Rehabilitation Center
Istanbul, Bostancı/Kadıköy, 34744
About this study
Official title: Effects of Adding End-Range Isometric Holds to Isotonic Knee Extensor Training on Isokinetic Performance in Sedentary Adults: A Randomized Controlled Trial
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?
Read more
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
Read the detailed description
Quadriceps femoris weakness is associated with several musculoskeletal conditions, including knee osteoarthritis, and is a common target of physiotherapy strengthening protocols. While isotonic and isokinetic strengthening methods have each been studied separately, it remains unclear whether adding an isometric hold to isotonic exercise provides additional benefit in isokinetic strength outcomes. This study addressed that question.
This was a randomized, two-arm study conducted at the Sportomed Sports Health and Orthopedic Rehabilitation Clinic (December 2014-May 2015). Forty-six sedentary, healthy adults aged 18-40 years were enrolled, with 43 completing the 8-week protocol. Exclusion criteria included lower-extremity musculoskeletal problems, prior lower-extremity surgery or significant trauma, low back pain, cardiac or neurological conditions, and chronic systemic disease. The study was approved by the Istanbul Medipol University Non-Interventional Clinical Research Ethics Committee (decision no. 257, 07.11.2014), and written informed consent was obtained from all participants.
Participants were randomized to two groups. Both performed isotonic knee-extension exercise (2 sets × 10 repetitions, 60% of 1RM) 3 days/week for 8 weeks, with weekly load progression (~5%) and 60 seconds rest between sets. Group 1 (n=21) added a 5-second isometric hold at 0° knee extension at the end of each repetition; Group 2 (n=22) performed the isotonic protocol without this addition.
Outcomes were assessed at baseline and after 8 weeks: thigh circumference, 1RM isotonic quadriceps strength, and isokinetic peak torque (PT, Nm) at 60°/second and 180°/second using a CSMI Humac Norm 2004 dynamometer. Baseline assessments also included range of motion, manual muscle testing, and physical activity level (IPAQ Short Form).
Statistical analysis was performed using NCSS 2007. Normality was assessed with Shapiro-Wilk testing. Between-group comparisons used independent t-tests or Mann-Whitney U tests as appropriate; within-group pre-post comparisons used paired t-tests. Categorical variables were compared using chi-square testing, and correlations using Pearson testing. Significance was set at p<0.05.
- Conditions
- Quadriceps Muscle Strength, Isokinetic
- Being tested
- Isotonic Exercise With Added Isometric Hold, Isotonic Exercise Only
- Keywords
- quadriceps muscle, isokinetic exercise, knee extensor strength, isometric contraction, resistance training
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Isotonic Exercise With Added Isometric HoldOther
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 Exercise OnlyOther
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.
| Study group | Role | What they receive |
|---|---|---|
| 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. Receives: 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. Receives: Other: Isotonic Exercise Only |
What is being measured
The primary outcome is the main question the study is designed to answer.
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).
Measured: Baseline and 8 weeks
Secondary outcomes (2)
Change in Quadriceps Femoris 1-Repetition Maximum (1RM) Isotonic Strength
Quadriceps femoris 1-repetition maximum isotonic strength was measured bilaterally using a leg-extension apparatus, with each disk increment corresponding to 10 lbs (4.54 kg).
Measured: Baseline and 8 weeks
Change in Thigh Circumference
Thigh circumference was measured bilaterally, 15 cm proximal to the superior border of the patella, using a measuring tape, in the supine position.
Measured: Baseline and 8 weeks
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted25 Jun 2026
- Study start12 Dec 2014
- Primary completion26 May 2015
- Study completion6 Jul 2015
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Quadriceps Muscle StrengthStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Model description
- 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.
- Masking
- Single blind
- Who is masked
- Participant
- Enrolment
- 43 participants (actual)
Sponsor and investigators
- Lead sponsor
- Yeditepe University
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Feyza Sule BADILLI HANTAL, Yeditepe University
- Investigators
- Feyza Şule Hantal, PhD, Study director, Yeditepe University
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07667543
- Sponsor's protocol ID
- 127742
- Status last verified
- Jun 2026
- First submitted
- 19 Jun 2026
- Last updated
- 30 Jun 2026
- Results posted
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
Study at a glance
From the registry record, last updated by the sponsor on 30 Jun 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Effects of Adding End-Range Isometric Holds to Isotonic Knee Extensor Training on Isokinetic Performance in Sedentary Adults: A Randomized Controlled Trial
- ClinicalTrials.gov ID
- NCT07667543
- Acronym / sponsor ID
- 127742
- Conditions
- Quadriceps Muscle Strength, Isokinetic
- Keywords
- quadriceps muscle, isokinetic exercise, knee extensor strength, isometric contraction, resistance training
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 43 participants (actual)
- Lead sponsor
- Yeditepe UniversityUniversity, hospital or other
- Study start
- 12 Dec 2014 (actual)
- Primary completion
- 26 May 2015 (actual)
- Study completion
- 6 Jul 2015 (actual)
- First posted
- 25 Jun 2026 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
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
Detailed description
Quadriceps femoris weakness is associated with several musculoskeletal conditions, including knee osteoarthritis, and is a common target of physiotherapy strengthening protocols. While isotonic and isokinetic strengthening methods have each been studied separately, it remains unclear whether adding an isometric hold to isotonic exercise provides additional benefit in isokinetic strength outcomes. This study addressed that question.
This was a randomized, two-arm study conducted at the Sportomed Sports Health and Orthopedic Rehabilitation Clinic (December 2014-May 2015). Forty-six sedentary, healthy adults aged 18-40 years were enrolled, with 43 completing the 8-week protocol. Exclusion criteria included lower-extremity musculoskeletal problems, prior lower-extremity surgery or significant trauma, low back pain, cardiac or neurological conditions, and chronic systemic disease. The study was approved by the Istanbul Medipol University Non-Interventional Clinical Research Ethics Committee (decision no. 257, 07.11.2014), and written informed consent was obtained from all participants.
Participants were randomized to two groups. Both performed isotonic knee-extension exercise (2 sets × 10 repetitions, 60% of 1RM) 3 days/week for 8 weeks, with weekly load progression (~5%) and 60 seconds rest between sets. Group 1 (n=21) added a 5-second isometric hold at 0° knee extension at the end of each repetition; Group 2 (n=22) performed the isotonic protocol without this addition.
Outcomes were assessed at baseline and after 8 weeks: thigh circumference, 1RM isotonic quadriceps strength, and isokinetic peak torque (PT, Nm) at 60°/second and 180°/second using a CSMI Humac Norm 2004 dynamometer. Baseline assessments also included range of motion, manual muscle testing, and physical activity level (IPAQ Short Form).
Statistical analysis was performed using NCSS 2007. Normality was assessed with Shapiro-Wilk testing. Between-group comparisons used independent t-tests or Mann-Whitney U tests as appropriate; within-group pre-post comparisons used paired t-tests. Categorical variables were compared using chi-square testing, and correlations using Pearson testing. Significance was set at p<0.05.
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Single blind (participant)
- Number of arms
- 2
- Model description
- 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.
| Arm | Type | Receives |
|---|---|---|
| Isotonic + Isometric Hold Group | Experimental | Other: Isotonic Exercise With Added Isometric HoldParticipants 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. |
| Isotonic Only Group | Active comparator | Other: Isotonic Exercise OnlyParticipants 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. |
Who may qualify
- Ages
- 18 to 40 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult
Key inclusion criteria (3 listed)
- Age 18-40 years
- Sedentary lifestyle (low physical activity level)
- Healthy individuals with no known knee-related disability
Key exclusion criteria (6 listed)
- 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
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Isotonic Exercise With Added Isometric HoldIsotonic 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. | Other | Isotonic + Isometric Hold Group |
| Isotonic Exercise OnlyIsotonic 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. | Other | Isotonic Only Group |
Primary outcome
Change in Quadriceps Femoris Isokinetic Peak Torque
Time frame: Baseline and 8 weeks
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).
2 secondary outcomes
Change in Quadriceps Femoris 1-Repetition Maximum (1RM) Isotonic Strength
Time frame: Baseline and 8 weeks
Change in Thigh Circumference
Time frame: Baseline and 8 weeks
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 30 Jun 2026.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Feyza Şule Hantal, PhD study director
Yeditepe University
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Isotonic Exercise With Added Isometric Hold and Isotonic Exercise Only in people with Quadriceps Muscle Strength and Isokinetic, run by Yeditepe University at 1 site in Turkey (Türkiye).
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 3 inclusion and 6 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 30 Jun 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Turkey (Türkiye). Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Change in Quadriceps Femoris Isokinetic Peak Torque (time frame: Baseline and 8 weeks). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 30 Jun 2026.