SLV
Sensitivity of the Load-Velocity Relationship Variables to Discriminate the Level of Fatigue Induced by Multiple Sets of the Smith-Machine Squat Exercise
Sponsor study identifier
observational
28
1 country
1
Study Start
May 5, 2024
Actual (reported)Primary Completion
May 10, 2024
Actual (reported)Study Completion
October 10, 2024
Actual (reported)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.
Registry-reported information. Elapsed time and enrollment totals alone do not measure study progress or recruitment pace.
October 10, 2024
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Dates and qualifiers reported by the registry. Estimated dates do not confirm that a milestone has occurred.
May 5, 2024
Actual (reported)May 10, 2024
Actual (reported)October 10, 2024
Actual (reported)November 27, 2025
Actual (reported)December 29, 2025
Actual (reported)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.
Baseline (pre-session) and immediately post-session (within 15 minutes)
Change in Theoretical Maximal Velocity (v0) Derived From the Load-Velocity Relationship
Baseline (pre-session) and 15 minutes post-session
Change in Area Under the Load-Velocity Relationship Line (Aline)
Baseline (pre-session) and immediately post-session (within 15 minutes)
Change in One-Repetition Maximum (1RM) in the Smith-Machine Squat
Baseline (pre-session) and immediately post-session (within 15 minutes)
Control Protocol Arm: Participants completed no exercise between the pre- and post-session load-velocity tests.
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.
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.
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.
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.
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.
İstanbul Gelişim Üniversity
Istanbul, avcılar, 34310, Turkey (Türkiye)
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.
Deniz Şentürk, PhD
Istanbul Gelisim University
28 participants (actual enrollment reported by the registry).
First Submitted
November 27, 2025
First Posted
December 29, 2025
Study Start
May 5, 2024
Actual (reported)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.
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Primary Completion
May 10, 2024
Actual (reported)Study Completion
October 10, 2024
Actual (reported)Last Updated
December 29, 2025
Record last verified: 2025-12
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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Source: ClinicalTrials.gov.
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