Isometric ExerciseNCT07207135
Most Effective Knee Joint Angle Pair for Isometric Exercise
A study testing Isometric Exercise at 15° and 90° Knee Angles, Isometric Exercise at 30° and 105° Knee Angles and Isometric Exercise at 45° and 120° Knee Angles in people with Isometric Exercise and Exercise Training, run by Firat University at 1 site in Turkey (Türkiye).
Trial summary
This study investigated the effects of isometric exercises applied to the quadriceps and hamstring muscles at different knee joint angles on balance, joint position sense, and functional performance in healthy individuals. Read more about this study
- Who is it for?
- Ages 18 to 30 yearsHealthy volunteers can take part
- Conditions the study is for
- Isometric Exercise, Exercise Training, Musculoskeletal Function
- What is being tested?
- Isometric Exercise at 15° and 90° Knee Angles, Isometric Exercise at 30° and 105° Knee Angles and Isometric Exercise at 45° and 120° Knee Angles
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 44 participants
- Where
- 1 siteTurkey (Türkiye)
- Study dates
- 15 Jan 2025to 30 May 2025
- 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 30 years
- All sexes
- Healthy volunteers accepted
- Adult
Who may be able to join
- Age between 18 and 30 years
- Voluntary participation with signed informed consent
- No history of knee pain
- No history of knee surgery
- No musculoskeletal pathology preventing ambulation
Who cannot join
- Presence of cardiovascular or pulmonary diseases that prevent exercise
- Inflammatory or infectious pathology of the knee joint
- Uncontrolled endocrinological disorders or significant systemic/organ insufficiency
- Neurological disorders affecting knee joint innervation
Trial locations and contacts
1 site in 1 country.
About this study
Official title: The Effect of Isometric Exercises Applied to the Quadriceps and Hamstring Muscles at Different Knee Angles on Balance, Joint Position Sense, and Functional Performance in Healthy Individuals
This study investigated the effects of isometric exercises applied to the quadriceps and hamstring muscles at different knee joint angles on balance, joint position sense, and functional performance in healthy individuals. Thirty participants aged 18-26 years were randomized into four groups and performed an eight-week training program, three times per week. Outcome measures included the Y Balance Test, digital goniometer assessments for joint position sense, and functional performance tests (stair climb and 30-second sit-to-stand). The results aim to identify which knee joint angles are most effective for improving neuromuscular function and may guide future rehabilitation and training protocols.
Read the detailed description
Isometric exercises applied to the quadriceps and hamstring muscles are widely used both in rehabilitation programs and in improving physical fitness in athletes. Isometric contractions occur when the muscle generates tension without changing its length, making them especially suitable in conditions where joint movement is limited or contraindicated. Previous studies have demonstrated the benefits of isometric training in increasing muscle strength, enhancing proprioception, and supporting functional performance. However, there is no clear consensus regarding the effects of isometric exercises performed at different knee joint angles on balance, joint position sense, and functional capacity.
The aim of this study was to investigate the effects of isometric exercises applied to the quadriceps and hamstring muscles at different knee angles (15°-90°, 30°-105°, 45°-120°, 60°-135°) on balance, joint position sense, and functional performance in healthy individuals. Participants aged 20-30 years, without knee pain, previous knee surgery, or pathologies preventing ambulation, were included. All participants were randomized into four groups. Each group performed progressive resistance exercises for the hip and ankle, combined with isometric exercises of the quadriceps and hamstring muscles at the specified knee angles.
The training program lasted eight weeks, with sessions three times per week. During each session, isometric contractions were performed against resistance for 10 seconds at the assigned knee angles, with standardized rest periods between sets. The number of repetitions was progressively increased throughout the program.
Assessments were conducted at baseline and after eight weeks. The following outcome measures were used:
Balance: Y Balance Test
Joint position sense: Digital goniometer measurements
Functional performance: Stair climb test and 30-second sit-to-stand test
The hypothesis of the study was that isometric exercises performed at different knee joint angles would result in different responses in balance, joint position sense, and functional performance. The findings are expected to provide valuable insights both for improving physical fitness in healthy populations and for guiding rehabilitation protocols in clinical populations.
- Conditions
- Isometric Exercise, Exercise Training, Musculoskeletal Function, Balance, Proprioception, and Functional Performance, Healthy Volunteers
- Being tested
- Isometric Exercise at 15° and 90° Knee Angles, Isometric Exercise at 30° and 105° Knee Angles, Isometric Exercise at 45° and 120° Knee Angles, Isometric Exercise at 60° and 135° Knee Angles
- Keywords
- Isometric Exercise, Knee Joint Angles, Joint Position Sense, Balance, Functional Performance, Exercise Therapy
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Isometric Exercise at 15° and 90° Knee AnglesOther
Participants performed quadriceps and hamstring isometric contractions at 15° and 90° of knee flexion. Each contraction lasted 10 seconds against resistance, three times per week for eight weeks, with progressive repetitions. Hip and ankle strengthening was also included.
Isometric Exercise at 30° and 105° Knee AnglesOther
Same protocol as Group 1, but at 30° and 105° of knee flexion.
Isometric Exercise at 45° and 120° Knee AnglesOther
Same protocol as Group 1, but at 45° and 120° of knee flexion.
Isometric Exercise at 60° and 135° Knee AnglesOther
Same protocol as Group 1, but at 60° and 135° of knee flexion.
| Study group | Role | What they receive |
|---|---|---|
| Group 1 | Experimental | Isometric Exercise at 15° and 90° Knee Angles Receives: Other: Isometric Exercise at 15° and 90° Knee Angles |
| Group 2 | Experimental | Isometric Exercise at 30° and 105° Knee Angles Receives: Other: Isometric Exercise at 30° and 105° Knee Angles |
| Group 3 | Experimental | Isometric Exercise at 45° and 120° Knee Angles Receives: Other: Isometric Exercise at 45° and 120° Knee Angles |
| Group 4 | Experimental | Isometric Exercise at 60° and 135° Knee Angles Receives: Other: Isometric Exercise at 60° and 135° Knee Angles |
What is being measured
The primary outcome is the main question the study is designed to answer.
Balance Performance
Balance will be assessed using the Y Balance Test, which measures dynamic postural control in anterior, posteromedial, and posterolateral directions. Normalized reach distances will be recorded.
Measured: Baseline and after 8 weeks of intervention
Joint Position Sense
Proprioception will be evaluated using a digital goniometer at predetermined knee joint angles (15°, 30°, 45°, 60°, 90°, and 120°). Absolute angular error between target and reproduced angles will be calculated.
Measured: Baseline and after 8 weeks of intervention
Functional Performance- Stair Climb Test
unctional performance will be assessed using the Stair Climb Test (time to ascend and descend 9 steps)
Measured: Baseline and after 8 weeks of intervention
Secondary outcomes (1)
Functional Performance - 30-Second Sit-to-Stand Test
Number of repetitions completed in 30 seconds.
Measured: Baseline and after 8 weeks.
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted3 Oct 2025
- Study start15 Jan 2025
- Primary completion12 May 2025
- Study completion30 May 2025
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Isometric ExerciseStudies 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 randomly assigned to one of four parallel groups. Each group performed an eight-week exercise program consisting of progressive resistance training for the hip and ankle combined with isometric quadriceps and hamstring exercises at specific knee joint angles (15°-90°, 30°-105°, 45°-120°, and 60°-135°). The intervention was delivered three times per week under the supervision of physiotherapists.
- Masking
- None (open label)
- Enrolment
- 44 participants (actual)
Sponsor and investigators
- Lead sponsor
- Firat University
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Muharrem Gökhan Beydağı, Firat University
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07207135
- Sponsor's protocol ID
- FU_MGBeydagi_Isometric
- Status last verified
- Sep 2025
- First submitted
- 25 Sep 2025
- Last updated
- 28 May 2026
- Results posted
- No
- Data monitoring committee
- Yes
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Study at a glance
From the registry record, last updated by the sponsor on 28 May 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- The Effect of Isometric Exercises Applied to the Quadriceps and Hamstring Muscles at Different Knee Angles on Balance, Joint Position Sense, and Functional Performance in Healthy Individuals
- ClinicalTrials.gov ID
- NCT07207135
- Acronym / sponsor ID
- FU_MGBeydagi_Isometric
- Conditions
- Isometric Exercise, Exercise Training, Musculoskeletal Function, Balance, Proprioception, and Functional Performance, Healthy Volunteers
- Keywords
- Isometric Exercise, Knee Joint Angles, Joint Position Sense, Balance, Functional Performance, Exercise Therapy
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 44 participants (actual)
- Lead sponsor
- Firat UniversityUniversity, hospital or other
- Study start
- 15 Jan 2025 (actual)
- Primary completion
- 12 May 2025 (actual)
- Study completion
- 30 May 2025 (actual)
- First posted
- 3 Oct 2025 (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.
This study investigated the effects of isometric exercises applied to the quadriceps and hamstring muscles at different knee joint angles on balance, joint position sense, and functional performance in healthy individuals. Thirty participants aged 18-26 years were randomized into four groups and performed an eight-week training program, three times per week. Outcome measures included the Y Balance Test, digital goniometer assessments for joint position sense, and functional performance tests (stair climb and 30-second sit-to-stand). The results aim to identify which knee joint angles are most effective for improving neuromuscular function and may guide future rehabilitation and training protocols.
Detailed description
Isometric exercises applied to the quadriceps and hamstring muscles are widely used both in rehabilitation programs and in improving physical fitness in athletes. Isometric contractions occur when the muscle generates tension without changing its length, making them especially suitable in conditions where joint movement is limited or contraindicated. Previous studies have demonstrated the benefits of isometric training in increasing muscle strength, enhancing proprioception, and supporting functional performance. However, there is no clear consensus regarding the effects of isometric exercises performed at different knee joint angles on balance, joint position sense, and functional capacity.
The aim of this study was to investigate the effects of isometric exercises applied to the quadriceps and hamstring muscles at different knee angles (15°-90°, 30°-105°, 45°-120°, 60°-135°) on balance, joint position sense, and functional performance in healthy individuals. Participants aged 20-30 years, without knee pain, previous knee surgery, or pathologies preventing ambulation, were included. All participants were randomized into four groups. Each group performed progressive resistance exercises for the hip and ankle, combined with isometric exercises of the quadriceps and hamstring muscles at the specified knee angles.
The training program lasted eight weeks, with sessions three times per week. During each session, isometric contractions were performed against resistance for 10 seconds at the assigned knee angles, with standardized rest periods between sets. The number of repetitions was progressively increased throughout the program.
Assessments were conducted at baseline and after eight weeks. The following outcome measures were used:
Balance: Y Balance Test
Joint position sense: Digital goniometer measurements
Functional performance: Stair climb test and 30-second sit-to-stand test
The hypothesis of the study was that isometric exercises performed at different knee joint angles would result in different responses in balance, joint position sense, and functional performance. The findings are expected to provide valuable insights both for improving physical fitness in healthy populations and for guiding rehabilitation protocols in clinical populations.
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Number of arms
- 4
- Model description
- Participants were randomly assigned to one of four parallel groups. Each group performed an eight-week exercise program consisting of progressive resistance training for the hip and ankle combined with isometric quadriceps and hamstring exercises at specific knee joint angles (15°-90°, 30°-105°, 45°-120°, and 60°-135°). The intervention was delivered three times per week under the supervision of physiotherapists.
| Arm | Type | Receives |
|---|---|---|
| Group 1 | Experimental | Other: Isometric Exercise at 15° and 90° Knee AnglesIsometric Exercise at 15° and 90° Knee Angles |
| Group 2 | Experimental | Other: Isometric Exercise at 30° and 105° Knee AnglesIsometric Exercise at 30° and 105° Knee Angles |
| Group 3 | Experimental | Other: Isometric Exercise at 45° and 120° Knee AnglesIsometric Exercise at 45° and 120° Knee Angles |
| Group 4 | Experimental | Other: Isometric Exercise at 60° and 135° Knee AnglesIsometric Exercise at 60° and 135° Knee Angles |
Who may qualify
- Ages
- 18 to 30 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult
Key inclusion criteria (5 listed)
- Age between 18 and 30 years
- Voluntary participation with signed informed consent
- No history of knee pain
- No history of knee surgery
- No musculoskeletal pathology preventing ambulation
Key exclusion criteria (4 listed)
- Presence of cardiovascular or pulmonary diseases that prevent exercise
- Inflammatory or infectious pathology of the knee joint
- Uncontrolled endocrinological disorders or significant systemic/organ insufficiency
- Neurological disorders affecting knee joint innervation
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 |
|---|---|---|
| Isometric Exercise at 15° and 90° Knee AnglesParticipants performed quadriceps and hamstring isometric contractions at 15° and 90° of knee flexion. Each contraction lasted 10 seconds against resistance, three times per week for eight weeks, with progressive repetitions. Hip and ankle strengthening was also included. | Other | Group 1 |
| Isometric Exercise at 30° and 105° Knee AnglesSame protocol as Group 1, but at 30° and 105° of knee flexion. | Other | Group 2 |
| Isometric Exercise at 45° and 120° Knee AnglesSame protocol as Group 1, but at 45° and 120° of knee flexion. | Other | Group 3 |
| Isometric Exercise at 60° and 135° Knee AnglesSame protocol as Group 1, but at 60° and 135° of knee flexion. | Other | Group 4 |
Primary outcome
Balance Performance
Time frame: Baseline and after 8 weeks of intervention
Balance will be assessed using the Y Balance Test, which measures dynamic postural control in anterior, posteromedial, and posterolateral directions. Normalized reach distances will be recorded.
Joint Position Sense
Time frame: Baseline and after 8 weeks of intervention
Proprioception will be evaluated using a digital goniometer at predetermined knee joint angles (15°, 30°, 45°, 60°, 90°, and 120°). Absolute angular error between target and reproduced angles will be calculated.
Functional Performance- Stair Climb Test
Time frame: Baseline and after 8 weeks of intervention
unctional performance will be assessed using the Stair Climb Test (time to ascend and descend 9 steps)
1 secondary outcome
Functional Performance - 30-Second Sit-to-Stand Test
Time frame: Baseline and after 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 28 May 2026.
- Individual participant dataSharing planned: No
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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.
The record lists no contact. Use the official record to reach the sponsor.
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Isometric Exercise at 15° and 90° Knee Angles, Isometric Exercise at 30° and 105° Knee Angles and Isometric Exercise at 45° and 120° Knee Angles in people with Isometric Exercise and Exercise Training, run by Firat 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 5 inclusion and 4 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 28 May 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?
Balance Performance (time frame: Baseline and after 8 weeks of intervention). The study lists 3 primary outcomes in all. 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 28 May 2026.