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The Effect of Altering Knee Position and Squat Depth on VMO : VL EMG Ratio During Squat Exercises

PainSci » bibliography » Jaberzadeh et al 2016
Tags: exercise, biomechanics, patellar pain, strength, muscle, counter-intuitive, self-treatment, treatment, etiology, pro, arthritis, aging, pain problems, knee, leg, limbs, overuse injury, injury, running

Two articles on PainSci cite Jaberzadeh 2016: 1. The Complete Guide to Patellofemoral Pain Syndrome2. Patellofemoral Pain & the Vastus Medialis Myth

original abstract Abstracts here may not perfectly match originals, for a variety of technical and practical reasons. Some abstacts are truncated for my purposes here, if they are particularly long-winded and unhelpful. I occasionally add clarifying notes. And I make some minor corrections.

BACKGROUND: Patellofemoral pain syndrome is an extremely common condition, believed to be caused by altered activation of vastus medialis obliquus (VMO), leading to maltracking of the patella.

AIM: This study aimed to investigate the effect of altering knee movement and squat depth on the ratio of VMO and vastus lateralis (VMO : VL) during squat exercises.

METHOD: Eighteen (7 male and 11 female) healthy, asymptomatic participants performed semi-squat exercises with three squat depths (20°, 50° and 80° of knee flexion) while following three knee movement paths (neutral, varus or valgus). Normalized VMO : VL ratio from linear envelope surface electromyography was analysed.

RESULTS: No significant effect was found for gender (p = 0.87), leg dominance (p = 0.99) or knee position (p = 0.44). A significant effect was found for squat depth (p < 0.001) with both the 50° and 80° squats showing increases in VMO : VL ratio (p = 0.031 and p = 0.028), respectively. The VMO : VL ratio was not influenced by gender, leg dominance or knee position in semi-squat exercises.

DISCUSSION AND CONCLUSION: Increases in relative VMO activation did occur in 'deeper' squat depths (50° and 80° knee flexion) compared with the 20° condition. Further research is needed in this area concerning the effects of such exercise modifications on a symptomatic patellofemoral pain syndrome population. Copyright © 2015 John Wiley & Sons, Ltd.

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