NCT07307963

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

Sensitivity of the Load-Velocity Relationship Variables to Discriminate the Level of Fatigue Induced by Multiple Sets of the Smith-Machine Squat Exercise

• Status: Completed
• Phase: —
• Study type: Observational
• Enrollment: 28 (actual)
• Sponsor: Istanbul Gelisim University · Academic / Other
• Sex: Male
• Age: 18 Years – 35 Years
• Healthy volunteers: Accepted

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. 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.

Conditions

• Neuromuscular Fatigue
• Load-velocity Variables

Interventions

Type	Name	Description
OTHER	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	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.
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.

Timeline

• Start date: 2024-05-05
• Primary completion: 2024-05-10
• Completion: 2024-10-10
• First posted: 2025-12-29
• Last updated: 2025-12-29

Locations

1 site across 1 country: Turkey (Türkiye)