Neuromuscular FatigueSLVNCT07307963
Sensitivity of Load-Velocity Measures for Detecting Fatigue During Smith-Machine Squats
An observational study of Neuromuscular Fatigue and Load-velocity Variables, run by Istanbul Gelisim University at 1 site in Turkey (Türkiye).
Trial summary
The purpose of this study is to determine whether load-velocity (L-V) relationship variables (L0, v0, and Aline) are sensitive indicators of fatigue produced by different squat fatigue protocols. Read more about this study
- Who is it for?
- Ages 18 to 35 years, men onlyHealthy volunteers can take part
- Conditions the study is for
- Neuromuscular Fatigue, Load-velocity Variables
- What is being tested?
- Moderate-fatigue and High-fatigue
- How many people
- 28 participants
- Where
- 1 siteTurkey (Türkiye)
- Study dates
- 5 May 2024to 10 Oct 2024
- Phase
- Observational
- 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 35 years
- Men only
- Healthy volunteers accepted
- Adult
Study population: Twenty-eight physically trained males, with an average age of 23.3 years (standard deviation [SD]: 3.0 years; range: 20-36 years), willingly enrolled in this research endeavor. The participants exhibited a mean body mass of 78.1 kg (SD: 9.3 kg), a body height of 177.2 cm (SD: 3.3 cm), and a one-repetition maximum (1RM) for smith-machine squat (SMS) exercise of 150.9 kg (SD: 12.5 kg). All subjects possessed prior RT experience, averaging 5.0 years (SD: 2.6 years), and demonstrated proficiency in executing the SMS exercise during the familiarization session.
Who may be able to join
- Healthy males aged 18-40 years.
- Resistance-trained (minimum 2 years of regular lower-body resistance training and ≥2 sessions/week).
- Able to perform a proper smith-machine back squat with correct technique.
- 1-RM smith-machine squat measurable and ≥ bodyweight (or specify threshold used in study).
- No musculoskeletal injury of lower limbs or back in the past 6 months.
- Not using performance-enhancing drugs or anabolic steroids for the past 12 months.
- Willing and able to attend all testing and training sessions and provide written informed consent.
Who cannot join
- Any cardiovascular, pulmonary, metabolic, or neurological disease contraindicating intense exercise.
- Recent (≤6 months) lower-extremity or spinal surgery or acute injury.
- Current musculoskeletal pain or injury that limits squat performance.
- Use of medications that affect neuromuscular performance (e.g., systemic corticosteroids) or stimulant drugs.
- Regular participation in structured lower-body rehabilitation programs.
- Failure to complete familiarization or preliminary 1-RM testing.
- Inability or unwillingness to provide informed consent or follow study procedures.
Trial locations and contacts
1 site in 1 country.
Turkey (Türkiye)1 site
İstanbul Gelişim Üniversity
Istanbul, avcılar, 34310
About this study
Official title: Sensitivity of the Load-Velocity Relationship Variables to Discriminate the Level of Fatigue Induced by Multiple Sets of the Smith-Machine Squat Exercise
The purpose of this study is to determine whether load-velocity (L-V) relationship variables (L0, v0, and Aline) are sensitive indicators of fatigue produced by different squat fatigue protocols. The study aims to answer how accurately these L-V measures reflect changes in performance, particularly changes in one-repetition maximum (1RM), after varying levels of induced fatigue. Twenty-eight resistance-trained men completed three sessions involving different fatigue protocols or no training. L-V variables measured before and after each protocol were compared. The findings will help determine whether L-V relationship parameters can be used as practical and sensitive tools for monitoring fatigue during resistance training.
Read the detailed description
This study investigates how different levels of fatigue influence the parameters of the load-velocity (L-V) relationship during the Smith-machine squat exercise. After an initial familiarization and baseline testing session used to establish 1-repetition maximum (1RM) and to perform a repetition-to-failure test at 70% 1RM, participants completed three separate experimental sessions. Each session implemented a distinct fatigue protocol, and all protocols were performed between two incremental loading tests to determine pre-session and post-session L-V profiles.
The moderate-fatigue condition consisted of five sets at 70% 1RM, with participants performing half of their maximal possible repetitions per set. The high-fatigue condition required five sets performed to volitional failure using the same relative load. A control condition with no exercise was also included to establish non-fatigue reference values. L-V variables of interest included L0, v0, and Aline (calculated as L0 × v0 / 2). These variables were compared across conditions to determine their responsiveness to increasing levels of fatigue and their association with changes in neuromuscular performance, particularly reductions in 1RM strength.
- Conditions
- Neuromuscular Fatigue, Load-velocity Variables
- Being tested
- Control Protocol (No Training), Moderate-fatigue, High-fatigue
- Keywords
- resistance training, fatigue, velocity-based training
- Medical subject headings
- Fatigue
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Control Protocol (No Training)Other
This intervention consists of no training or exercise during the session. Participants assigned to the control arm rest for the entire duration between the pre-session and post-session load-velocity assessments. No fatigue-inducing activity, resistance exercise, or additional intervention is administered, allowing all observed changes to reflect normal variation without training-related fatigue.
Moderate-fatigueOther
Participants performed five sets of Smith-machine squats at 70% of their 1-repetition maximum (1RM), completing half of the maximum possible repetitions in each set. This protocol was designed to induce a moderate level of neuromuscular fatigue without reaching complete exhaustion.
High-fatigueOther
This intervention involves no training or fatigue-inducing activity. Participants do not perform any squat sets between the pre- and post-session incremental loading tests. This condition serves as a baseline to determine natural variations in load-velocity measures, thereby eliminating the influence of exercise-induced fatigue.
| Study group | Role | What they receive |
|---|---|---|
| Control Condition | Control Protocol Arm:
Participants completed no exercise between the pre- and post-session load-velocity tests. Receives: Other: Control Protocol (No Training) | |
| Moderate-Fatigue Protocol | Participants performed 5 sets of the Smith-machine squat at 70% of their 1RM, completing half of the maximum possible number of repetitions in each set. This protocol was designed to induce a moderate level of fatigue while avoiding complete muscular failure. Receives: Other: Moderate-fatigue | |
| High-Fatigue Protocol | In the high-fatigue protocol, participants performed five sets of Smith-machine squats at 70% of their 1RM, completing each set to muscular failure. In every set, participants continued lifting until they could no longer complete a full repetition with proper technique. This protocol was designed to induce a high level of neuromuscular fatigue and to test the sensitivity of load-velocity variables under maximal fatigue conditions. Receives: Other: High-fatigue |
What is being measured
The primary outcome is the main question the study is designed to answer.
Change in Theoretical Maximal Load (L0) Derived From the Load-Velocity Relationship
Difference in theoretical maximal load (L0, kg) derived from the load-velocity relationship between baseline (pre-session) and immediately post-session incremental loading tests.
Measured: Baseline (pre-session) and immediately post-session (within 15 minutes)
Secondary outcomes (3)
Change in Theoretical Maximal Velocity (v0) Derived From the Load-Velocity Relationship
Difference in theoretical maximal velocity (v0, m/s) derived from the load-velocity relationship between baseline (pre-session) and immediately post-session incremental loading tests.
Measured: Baseline (pre-session) and 15 minutes post-session
Change in Area Under the Load-Velocity Relationship Line (Aline)
Difference in area under the load-velocity relationship line (Aline, calculated as L0 × v0 / 2) between baseline (pre-session) and immediately post-session incremental loading tests.
Measured: Baseline (pre-session) and immediately post-session (within 15 minutes)
Change in One-Repetition Maximum (1RM) in the Smith-Machine Squat
Difference in one-repetition maximum (1RM, kg) in the smith-machine squat between baseline (pre-session) and immediately post-session incremental loading tests.
Measured: Baseline (pre-session) and immediately post-session (within 15 minutes)
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted29 Dec 2025
- Study start5 May 2024
- Primary completion10 May 2024
- Study completion10 Oct 2024
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (1)Papers the sponsor has linked to this study.
- Other trials for Neuromuscular FatigueStudies 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
- Observational
- Observational model
- Case crossover
- Time perspective
- Cross-sectional
- Enrolment
- 28 participants (actual)
Sponsor and investigators
- Lead sponsor
- Istanbul Gelisim University
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Deniz ŞENTÜRK, Istanbul Gelisim University
- Investigators
- Deniz Şentürk, PhD, Principal investigator, Istanbul Gelisim University
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07307963
- Sponsor's protocol ID
- 2024/04/67
- Acronym
- SLV
- Status last verified
- Dec 2025
- First submitted
- 27 Nov 2025
- Last updated
- 29 Dec 2025
- Results posted
- No
- Data monitoring committee
- Yes
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Yes: Individual participant data (IPD) will be shared after de-identification. Data will be available to qualified researchers upon reasonable request for academic purposes. Access will be provided following publication of the primary results. Researchers will be required to submit a brief proposal describing the intended use of the data, and data will be shared through secure, controlled access. No identifiable information will be released.
Publications
Senturk D, Kumak A, Janicijevic D. Sensitivity of the load-velocity relationship variables to discriminate the level of fatigue induced by multiple sets of the smith-machine squat exercise. BMC Sports Sci Med Rehabil. 2026 Feb 27;18(1):121. doi: 10.1186/s13102-026-01615-x.
PubMed 41761347
Study at a glance
From the registry record, last updated by the sponsor on 29 Dec 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Sensitivity of the Load-Velocity Relationship Variables to Discriminate the Level of Fatigue Induced by Multiple Sets of the Smith-Machine Squat Exercise
- ClinicalTrials.gov ID
- NCT07307963
- Acronym / sponsor ID
- SLV / 2024/04/67
- Conditions
- Neuromuscular Fatigue, Load-velocity Variables
- Keywords
- resistance training, fatigue, velocity-based training
- Study type
- Observational
- Recruitment status
- Completed
- Enrolment
- 28 participants (actual)
- Lead sponsor
- Istanbul Gelisim UniversityUniversity, hospital or other
- Study start
- 5 May 2024 (actual)
- Primary completion
- 10 May 2024 (actual)
- Study completion
- 10 Oct 2024 (actual)
- First posted
- 29 Dec 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.
The purpose of this study is to determine whether load-velocity (L-V) relationship variables (L0, v0, and Aline) are sensitive indicators of fatigue produced by different squat fatigue protocols. The study aims to answer how accurately these L-V measures reflect changes in performance, particularly changes in one-repetition maximum (1RM), after varying levels of induced fatigue. Twenty-eight resistance-trained men completed three sessions involving different fatigue protocols or no training. L-V variables measured before and after each protocol were compared. The findings will help determine whether L-V relationship parameters can be used as practical and sensitive tools for monitoring fatigue during resistance training.
Detailed description
This study investigates how different levels of fatigue influence the parameters of the load-velocity (L-V) relationship during the Smith-machine squat exercise. After an initial familiarization and baseline testing session used to establish 1-repetition maximum (1RM) and to perform a repetition-to-failure test at 70% 1RM, participants completed three separate experimental sessions. Each session implemented a distinct fatigue protocol, and all protocols were performed between two incremental loading tests to determine pre-session and post-session L-V profiles.
The moderate-fatigue condition consisted of five sets at 70% 1RM, with participants performing half of their maximal possible repetitions per set. The high-fatigue condition required five sets performed to volitional failure using the same relative load. A control condition with no exercise was also included to establish non-fatigue reference values. L-V variables of interest included L0, v0, and Aline (calculated as L0 × v0 / 2). These variables were compared across conditions to determine their responsiveness to increasing levels of fatigue and their association with changes in neuromuscular performance, particularly reductions in 1RM strength.
Study design
- Observational model
- Case crossover
- Time perspective
- Cross-sectional
- Number of arms
- 3
| Arm | Type | Receives |
|---|---|---|
| Control Condition | – | Other: Control Protocol (No Training)Control Protocol Arm: Participants completed no exercise between the pre- and post-session load-velocity tests. |
| Moderate-Fatigue Protocol | – | Other: Moderate-fatigueParticipants performed 5 sets of the Smith-machine squat at 70% of their 1RM, completing half of the maximum possible number of repetitions in each set. This protocol was designed to induce a moderate level of fatigue while avoiding complete muscular failure. |
| High-Fatigue Protocol | – | Other: High-fatigueIn the high-fatigue protocol, participants performed five sets of Smith-machine squats at 70% of their 1RM, completing each set to muscular failure. In every set, participants continued lifting until they could no longer complete a full repetition with proper technique. This protocol was designed to induce a high level of neuromuscular fatigue and to test the sensitivity of load-velocity variables under maximal fatigue conditions. |
Who may qualify
- Ages
- 18 to 35 years
- Sex
- Male only
- Healthy volunteers
- Accepted
- Age groups
- Adult
- Study population
- Twenty-eight physically trained males, with an average age of 23.3 years (standard deviation [SD]: 3.0 years; range: 20-36 years), willingly enrolled in this research endeavor. The participants exhibited a mean body mass of 78.1 kg (SD: 9.3 kg), a body height of 177.2 cm (SD: 3.3 cm), and a one-repetition maximum (1RM) for smith-machine squat (SMS) exercise of 150.9 kg (SD: 12.5 kg). All subjects possessed prior RT experience, averaging 5.0 years (SD: 2.6 years), and demonstrated proficiency in executing the SMS exercise during the familiarization session.
Key inclusion criteria (7 listed)
- Healthy males aged 18-40 years.
- Resistance-trained (minimum 2 years of regular lower-body resistance training and ≥2 sessions/week).
- Able to perform a proper smith-machine back squat with correct technique.
- 1-RM smith-machine squat measurable and ≥ bodyweight (or specify threshold used in study).
- No musculoskeletal injury of lower limbs or back in the past 6 months.
Key exclusion criteria (7 listed)
- Any cardiovascular, pulmonary, metabolic, or neurological disease contraindicating intense exercise.
- Recent (≤6 months) lower-extremity or spinal surgery or acute injury.
- Current musculoskeletal pain or injury that limits squat performance.
- Use of medications that affect neuromuscular performance (e.g., systemic corticosteroids) or stimulant drugs.
- Regular participation in structured lower-body rehabilitation programs.
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 |
|---|---|---|
| Control Protocol (No Training)This intervention consists of no training or exercise during the session. Participants assigned to the control arm rest for the entire duration between the pre-session and post-session load-velocity assessments. No fatigue-inducing activity, resistance exercise, or additional intervention is administered, allowing all observed changes to reflect normal variation without training-related fatigue. | Other | Control Condition |
| Moderate-fatigueParticipants performed five sets of Smith-machine squats at 70% of their 1-repetition maximum (1RM), completing half of the maximum possible repetitions in each set. This protocol was designed to induce a moderate level of neuromuscular fatigue without reaching complete exhaustion. | Other | Moderate-Fatigue Protocol |
| High-fatigueThis intervention involves no training or fatigue-inducing activity. Participants do not perform any squat sets between the pre- and post-session incremental loading tests. This condition serves as a baseline to determine natural variations in load-velocity measures, thereby eliminating the influence of exercise-induced fatigue. | Other | High-Fatigue Protocol |
Primary outcome
Change in Theoretical Maximal Load (L0) Derived From the Load-Velocity Relationship
Time frame: Baseline (pre-session) and immediately post-session (within 15 minutes)
Difference in theoretical maximal load (L0, kg) derived from the load-velocity relationship between baseline (pre-session) and immediately post-session incremental loading tests.
3 secondary outcomes
Change in Theoretical Maximal Velocity (v0) Derived From the Load-Velocity Relationship
Time frame: Baseline (pre-session) and 15 minutes post-session
Change in Area Under the Load-Velocity Relationship Line (Aline)
Time frame: Baseline (pre-session) and immediately post-session (within 15 minutes)
Change in One-Repetition Maximum (1RM) in the Smith-Machine Squat
Time frame: Baseline (pre-session) and immediately post-session (within 15 minutes)
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 29 Dec 2025.
- Derived from this study: PubMed 41761347Senturk D, Kumak A, Janicijevic D. Sensitivity of the load-velocity relationship variables to discriminate the level of fatigue induced by multiple sets of the smith-machine squat exercise. BMC Sports Sci Med Rehabil. 2026 Feb 27;18(1):121. doi: 10.1186/s13102-026-01615-x.
- Individual participant dataSharing planned: Yes. Individual participant data (IPD) will be shared after de-identification. Data will be available to qualified researchers upon reasonable request for academic purposes. Access will be provided following publication of the primary results. Researchers will be required to submit a brief proposal describing the intended use of the data, and data will be shared through secure, controlled access. No identifiable information will be released.
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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.
Deniz Şentürk, PhD principal investigator
Istanbul Gelisim University
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
An observational study of Neuromuscular Fatigue and Load-velocity Variables, run by Istanbul Gelisim 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 7 inclusion and 7 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 29 Dec 2025. 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 Theoretical Maximal Load (L0) Derived From the Load-Velocity Relationship (time frame: Baseline (pre-session) and immediately post-session (within 15 minutes)). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT07307963, which also lists 1 linked publication.
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 29 Dec 2025.