Electromyographic Evaluation of Quadriceps During Eccentric Decline Squat

Study Overview
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Brief Summary
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Previous studies have generally investigated patellar tendon stiffness, cross-sectional area of patellar tendon, patellar tendon length, patellar force and patellafemoral forces during decline squat. However, there is just a few study about electromyographic (EMG) activity during the eccentric squating, which is about rectus femoris (RF) recruitment. In the present study the investigators primarly aimed to quantify the activation of RF, vastus lateralis (VL), and vastus medialis obliqus (VMO) during eccentric squat on different decline angle (0, 5°, 10°, 15°, 20°). An additional purpose of our study was to compare the changes in muscle activation at various arc of knee flexion motion (degrees of 0-30, 30-60, 60-90, 0-60, 30-90, 0-90).The investigators hypothesised that the recruitment of RF, VL, and VMO during eccentric squat would differ according to decline angle and arc of motion.

Detailed Description
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The squat procedure in each condition will be repeated 10 times on a treadmill. The treadmill will be used to adjust the degree of decline in a standard manner. There will be a metronome to keep the speed of exercise in the same rhythm. All squats will be performed with a weighted barbell. The weight of it will be set as in ratio 30% of the participant's body weight

Official Title
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Electromyographic Evaluation of Quadriceps During Eccentric Decline Squat: An Investigation of the Effect of Decline Angle and Arc of Motion

Conditions
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Patellar Tendinopathy

Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: had exercised regularly (>3 days in a week) for at least six months. older than 18 years old. Exclusion Criteria: had patellofemoral pain, knee pain otherwise unrelated to the knee extensor mechanism and other injuries that would restrict performance of the tasks (e.g. ankle pathology).

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Electromyographic measurement of muscle activation | Surface electromyographic (EMG) system (Noraxon Telemyo DTS System, Scottsdale, USA) will be use to measure the muscle activation ratios of RF, VL, and VMO. Electrodes will be placed according to Surface EMG for noninvasive assessment of muscles (SENIAM) recommendations on the dominant leg. The muscle activation during eccentric phase of the decline squat for RF, VL, and VMO will be determined. The decline squat will be performed under different conditions (various decline angle: 0, 5, 10,15, 20 degree) The muscle activation will also be investigated within various arc of motion of knee flexion (0-30, 30-60, 60-90, 0-60, 0-90, 30-90) which is determined using the motion analysis system (Noraxon, MYOmotion Scottsdale, USA). | 50 minutes | 
| Maximal voluntary isometric contractions (MVICs) | MVICs for the RF, VL, and VMO at their manual muscle test positions will be assessed within 3 trials, which lasts 5 seconds. The muscle test position will be standardized 90 degrees hip flexion and 60 degrees knee flexion. One minute a rest period will be between each trial. The peak EMG amplitude will be used for the normalization. | 5 minutes | 
| Normalized EMG values | The amount of muscle activation in each condition will be proportioned to MVICs value for normalization using a calculator. The value will be represented in percentile (%). | 5 minutes | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Weight | The participant's weight will be determined a weighing machine inkilogram. | 1 minute | 
| Height | The participant's height will be measured in cm. | 1 minute | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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eccentric squatting, electromyografic activation, exercise, patellar tendinopathy