Muscle Activation Patterns During Different Squat Techniques

Abstract

Slater, LV, and Hart, JM. Muscle activation patterns during different squat techniques. J Strength Cond Res 31(3): 667-676, 2017-Bilateral squats are frequently used exercises in sport performance programs. Lower extremity muscle activation may change based on knee alignment during the performance of the exercise. The purpose of this study was to compare lower extremity muscle activation patterns during different squat techniques. Twenty-eight healthy, uninjured subjects (19 women, 9 men, 21.5 ± 3 years, 170 ± 8.4 cm, 65.7 ± 11.8 kg) volunteered. Electromyography (EMG) electrodes were placed on the vastus lateralis, vastus medialis, rectus femoris, biceps femoris, and the gastrocnemius of the dominant leg. Participants completed 5 squats while purposefully displacing the knee anteriorly (AP malaligned), 5 squats while purposefully displacing the knee medially (ML malaligned) and 5 squats with control alignment (control). Normalized EMG data (MVIC) were reduced to 100 points and represented as percentage of squat cycle with 50% representing peak knee flexion and 0 and 99% representing fully extended. Vastus lateralis, medialis, and rectus femoris activity decreased in the medio-lateral (ML) malaligned squat compared with the control squat. In the antero-posterior (AP) malaligned squat, the vastus lateralis, medialis, and rectus femoris activity decreased during initial descent and final ascent; however, vastus lateralis and rectus femoris activation increased during initial ascent compared with the control squat. The biceps femoris and gastrocnemius displayed increased activation during both malaligned squats compared with the control squat. In conclusion, participants had altered muscle activation patterns during squats with intentional frontal and sagittal malalignment as demonstrated by changes in quadriceps, biceps femoris, and gastrocnemius activation during the squat cycle.

Sport Biomechanics Applications Using Inertial, Force, and EMG Sensors: A Literature Overview

“…The majority of the studies included the recordings of less than nine muscles [ 72 , 73 , 77 – 85 , 87 , 91 – 95 , 98 – 106 , 158 ], while only a few considered a number between nine and 16 [ 74 , 76 , 86 , 88 , 90 , 96 ] or bigger than 16 [ 71 , 97 ]. Most of the studies considered muscles of the lower limb [ 71 – 73 , 77 , 78 , 81 , 83 – 85 , 89 , 90 , 92 , 93 , 95 , 96 , 98 , 104 , 106 , 115 ], with the remaining focussing on the trunk and/or upper limb [ 74 , 76 , 80 , 82 , 87 , 94 , 100 , 102 , 103 , 106 ] or both the upper and lower body [ 79 , 86 , 88 , 91 , 97 , 99 , 101 ]. Bilateral recordings (involving the left and right hand side of the same muscles) were less common [ 71 , 74 , 77 , 82 , 86 , 88 , 90 , 97 , 98 , 101 ] than ipsilateral [ 72 , 7...…”

Early Functional and Morphological Muscle Adaptations During Short-Term Inertial-Squat Training

“…When muscles of a whole region (i.e., thighs) are assessed after being non-uniformly recruited, the distribution of water is increased in the most active muscles but it is decreased in less active muscles ( Norrbrand et al, 2011 ). Thus, acute decreases in the T2 signal in HAMS muscles after squat exercise indicate relative inferior activation compared to QUAD muscles, but not a lack of activation ( Slater and Hart, 2017 ).…”

“…T2 shifts in analytic (i.e., single joint) exercises are related to other variables that are more relevant for promoting muscle hypertrophy ( Adams et al, 1992 ) (such as magnitude and time producing mechanical tension, Schoenfeld, 2010 ). Although metabolic activity and T2 changes might correlate with mechanical tension and morphological changes in some situations, results suggest that this relation is weakened in complex multi-joint movements such as the squat, in which antagonistic and synergistic muscle groups are recruited throughout the movement ( Slater and Hart, 2017 ). For instance, the HAMS muscle group displays a negative T2 shift in the squat ( Norrbrand et al, 2011 ), despite being electromyographically activated and under tension ( Caterisano et al, 2002 ).…”

Mechanical model for estimating wear in tibio-femoral connection in total knee replacements

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