Strength & Conditioning
The purpose of this study was to examine the kinetics, kinematics and muscle activation of the knee and hip extensors during the eccentric (ECC) phase of the squat exercise. Resistance trained males (n=9) performed isotonic loaded ECC squats at loads from 20-150% of squat 1-rep max. Inverse dynamic calculations were used to identify knee and hip joint moment, and iEMG was used to quantify muscle activation of the vastus lateralis and gluteus maximus. In contrast to previous literature examining the concentric phase of the squat, this study found the knee extensors experienced the greatest loading, plateauing when exposed to a load of >120% of 1RM, with no changes in joint kinematics. Vastus lateralis iEMG plateaued after 80% of 1RM, suggesting activation-independent factors for this increase in joint moment. If maximising knee extensor loading to promote adaptation is a training object, this data recommends an ECC load of 120%.
Armstrong, Richard; Baltzopoulos, Vasilios; Langan-Evans, Carl; Clark, Dave; Jarvis, Jonathan; Stewart, Claire; and O'Brien, Thomas
"KINETICS, KINEMATICS AND MUSCLE ACTIVATION DURING ECCENTRIC SQUATTING,"
ISBS Proceedings Archive: Vol. 40:
1, Article 10.
Available at: https://commons.nmu.edu/isbs/vol40/iss1/10