NCT07532980

Quadriceps and Hamstring Activation Timing

Quadriceps and Hamstring Activation Timing During Functional Tasks Following ACL Reconstruction

• Status: Enrolling By Invitation
• Phase: —
• Study type: Observational
• Enrollment: 25 (estimated)
• Sponsor: KTO Karatay University · Academic / Other
• Sex: Male
• Age: 18 Years – 45 Years
• Healthy volunteers: Not accepted

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.

Detailed description

This study will be conducted as a cross-sectional, quantitative investigation involving male participants who have undergone ACL reconstruction using semitendinosus and gracilis tendon grafts. Electromyographic (EMG) signals will be collected using the Noraxon Ultium EMG system and analyzed with Noraxon MyoResearch XP software. Muscle activation onset timing will be assessed for the vastus medialis oblique (VMO), vastus lateralis (VL), semimembranosus (SM), semitendinosus (ST), and biceps femoris (BF). Participants will perform a standardized single-leg squat task, during which EMG-based activation timing will be recorded. The findings are expected to provide insight into neuromuscular control strategies and inform rehabilitation approaches following ACL reconstruction.

Conditions

• Anterior Cruciate Ligament Reconstruction
• Knee Injury
• Neuromuscular Control

Interventions

Type	Name	Description
DIAGNOSTIC_TEST	Electromyography	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.

Timeline

• Start date: 2026-04-20
• Primary completion: 2026-05-02
• Completion: 2026-05-15
• First posted: 2026-04-16
• Last updated: 2026-04-16

Locations

1 site across 1 country: Turkey (Türkiye)