Muscle Activation Differs between Three Different Knee Joint-Angle Positions during a Maximal Isometric Back Squat Exercise

Authors

Paulo Henrique Marchetti, Methodist University of Piracicaba
Josinaldo Jarbas da Silva, Methodist University of Piracicaba
Brad J. Schoenfeld, CUNY Lehman CollegeFollow
Priscyla Silva Monteiro Nardi, University of Sao Paulo
Silvio Luis Pecoraro, Methodist University of Piracicaba
Julia Maria D'Andrea Greve, University of Sao Paulo
Erin Hartigan, University of New England

Document Type

Article

Publication Date

6-26-2016

Abstract

The purpose of this study was to compare muscle activation of the lower limb muscles when performing a maximal isometric back squat exercise over three different positions. Fifteen young, healthy, resistance-trained men performed an isometric back squat at three knee joint angles (20∘, 90∘, and 140∘) in a randomized, counterbalanced fashion. Surface electromyography was used to measure muscle activation of the vastus lateralis (VL), vastus medialis (VM), rectus femoris (RF), biceps femoris (BF), semitendinosus (ST), and gluteusmaximus (GM). In general,muscle activity was the highest at 90∘ for the three quadricepsmuscles, yet differences in muscle activation between knee angles were muscle specific. Activity of the GM was significantly greater at 20∘ and 90∘ compared to 140∘.The BF and ST displayed similar activation at all joint angles. In conclusion, knee position altersmuscles activation of the quadriceps and gluteus maximus muscles. An isometric back squat at 90∘ generates the highest overall muscle activation, yet an isometric back squat at 140∘ generates the lowest overall muscle activation of the VL and GM only.

Comments

This article was originally published in the Journal of Sports Medicine, available at http://dx.doi.org/10.1155/2016/3846123.

This is an open access article distributed under the Creative Commons Attribution License.