Sensitivity of Load-Velocity Measures for Detecting Fatigue During Smith-Machine Squats

NCT ID: NCT07307963

Last Updated: 2025-12-29

Study Results

Results pending

The study team has not published outcome measurements, participant flow, or safety data for this trial yet. Check back later for updates.

Basic Information

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Recruitment Status

COMPLETED

Total Enrollment

28 participants

Study Classification

OBSERVATIONAL

Study Start Date

2024-05-05

Study Completion Date

2024-10-10

Brief Summary

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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

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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

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Neuromuscular Fatigue Load-velocity Variables

Keywords

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resistance training fatigue velocity-based training

Study Design

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Observational Model Type

CASE_CROSSOVER

Study Time Perspective

CROSS_SECTIONAL

Study Groups

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Control Condition

Control Protocol Arm:

Participants completed no exercise between the pre- and post-session load-velocity tests.

Control Protocol (No Training)

Intervention Type 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-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.

Moderate-fatigue

Intervention Type OTHER

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-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.

High-fatigue

Intervention Type OTHER

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.

Interventions

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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.

Intervention Type OTHER

Moderate-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.

Intervention Type OTHER

High-fatigue

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.

Intervention Type OTHER

Eligibility Criteria

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Inclusion Criteria

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.

Exclusion Criteria

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.
Minimum Eligible Age

18 Years

Maximum Eligible Age

35 Years

Eligible Sex

MALE

Accepts Healthy Volunteers

Yes

Sponsors

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Istanbul Gelisim University

OTHER

Sponsor Role lead

Responsible Party

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Deniz ŞENTÜRK

Assistant Professor, PhD

Responsibility Role PRINCIPAL_INVESTIGATOR

Principal Investigators

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Deniz Şentürk, PhD

Role: PRINCIPAL_INVESTIGATOR

Istanbul Gelisim University

Locations

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İstanbul Gelişim Üniversity

Istanbul, avcılar, Turkey (Türkiye)

Site Status

Countries

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Turkey (Türkiye)

Other Identifiers

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2024/04/67

Identifier Type: -

Identifier Source: org_study_id