Quadriceps and Hamstring Activation Timing

NCT07532980 | Enrolling By Invitation

• 1 other identifier: 2025/029
• Study Type: observational
• Target: 25
• Locations: 1 country
• Sites: 1

Brief Summary

The anterior cruciate ligament (ACL) plays a crucial role in maintaining knee stability and enabling dynamic movement. ACL injuries are common, especially among athletes, and reconstruction surgery is frequently performed to restore knee function. Despite rehabilitation, neuromuscular deficits-particularly in muscle activation timing-may persist. This study will aim to evaluate the activation timing of quadriceps and hamstring muscles during a functional task in individuals who have undergone ACL reconstruction.

Conditions

Anterior Cruciate Ligament Reconstruction; Knee Injury; Neuromuscular Control

Keywords

ACL reconstruction; Electromyography; Muscle activation; Neuromuscular training; Rehabilitation

Outcome Measures

Primary Outcomes (1)

• Electromyography

  Muscle Activation Timing (%MVIC)

  Single session (approximately 15-20 minutes per participant)

Interventions

Electromyography DIAGNOSTIC_TEST

Electromyographic (EMG) data will be collected using the Noraxon Ultium EMG sensor system (Noraxon USA, Inc., Scottsdale, Arizona; sampling frequency: 4000 Hz per channel; gain: 1000 \[signal-to-noise ratio: 1 μV RMS\]; common mode rejection rate \[CMRR\]: -100 dB; input impedance: \>100 MΩ). Prior to electrode placement, any hair on the skin will be removed, and the skin will be cleansed with an alcohol swab to ensure optimal signal quality. Participants will be instructed to cross their arms over their chest and perform the squat slowly and in a controlled manner while maintaining balance. The knee flexion angle will be standardized at 60°, and this angle will be monitored and adjusted using an inclinometer integrated into the EMG system. A metronome will be used to control the squatting speed. Participants will be instructed to reach the squat position within 3 beats of the metronome, maintain the squat position for 3 beats, and return to the starting position within 3 beats.

Also known as: Single-leg-squat protocol

Eligibility Criteria

• Age: 18 Years - 45 Years
• Sex: male
• Healthy Volunteers: No
• Age Groups: Adult (18-64)
• Sampling Method: Non-Probability Sample

Study Population

The study population will consist of male individuals aged 18-45 years who have undergone anterior cruciate ligament (ACL) reconstruction using semitendinosus and gracilis tendon grafts.

You may qualify if:

• participants must be males between 18 and 45 years old
• must have undergone ACL repair surgery and be within 6 months to 2 years post-surgery
• should have completed a standard rehabilitation program post-surgery
• must provide written informed consent to participate in the study
• should be in generally good health, without any other significant medical conditions that could affect the study outcomes;
• must have returned to a moderate level of physical activity post-surgery

You may not qualify if:

• participants with any neurological disorders affecting lower limb function or any other musculoskeletal disorders or injuries that could affect the lower limb, apart from the ACL injury
• those with cardiovascular conditions that contraindicate participation in physical activity
• those with contraindications to kinesiological electromyography, such as skin conditions or allergies to electrodes
• those who are unable or unwilling to comply with study procedures and follow-ups
• those who have had multiple ACL surgeries on the same knee
• participants involved in ongoing litigation related to their ACL injury

Sponsors & Collaborators

• KTO Karatay University: lead

Study Sites (1)

Kto Karatay University

Konya, Karatay, 42030, Turkey (Türkiye)

Location

MeSH Terms

Conditions

Knee Injuries

Interventions

Electromyography

Condition Hierarchy (Ancestors)

Leg Injuries; Wounds and Injuries

Intervention Hierarchy (Ancestors)

Electrodiagnosis; Diagnostic Techniques and Procedures; Diagnosis; Myography

Study Design

• Study Type: observational
• Observational Model: OTHER
• Time Perspective: PROSPECTIVE
• Target Duration: 1 Day
• Sponsor Type: OTHER
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: April 9, 2026
• First Posted: April 16, 2026
• Study Start (Estimated): April 20, 2026
• Primary Completion (Estimated): May 2, 2026
• Study Completion (Estimated): May 15, 2026
• Last Updated: April 16, 2026

Record last verified: 2026-04

Data Sharing

• IPD Sharing: Will not share

Locations

TU (1)