King Grub
2015-03-13, 08:24
The purposes of this study were to measure the acute effects of knee wraps on knee and hip joint kinematics, dynamic muscle activation from the vastus lateralis and gluteus maximus, and rating of perceived exertion (RPE) during the back squat exercise at two different intensities. Fourteen resistance-trained men (age: 24±4 years, height: 176±6cm, body mass: 81±11kg, back squat 1RM: 107±30kg, 3±1 years of back squat experience) performed one set of 3 repetitions under four different conditions, to a depth of ∼90 degrees of knee joint flexion, and in random order: with knee wraps at 60% 1RM (KW60), with knee wraps at 90% 1RM (KW90), without knee wraps at 60% 1RM (NW60), and without knee wraps at 90% 1RM (NW90). The dependent variables obtained were vertical and horizontal bar displacement, peak joint angle in the sagittal plane (hip and knee joints), concentric and eccentric muscle activation (by integrated electromyography) from the vastus lateralis (VL) and gluteus maximus (GM), and RPE. For muscle activity, there were significant decreases in the vastus lateralis without knee wraps at 60% 1RM (P=0.013), and a significant increase without knee wraps at 90% 1RM (P=0.037). There was a significant increase in vastus lateralis muscle activity at 90% 1RM, when compared to 60% 1RM (KW: P=0.001, ES=1.51 and NW: P<0.001, ES=1.67). There was a decreases in gluteus maximus muscle activity without knee wraps only at 60% 1RM (P=0.014). There was a significant increase in gluteus maximus muscle activity at 90% 1RM, when compared to 60% 1RM (KW: P<0.001 and NW: P<0.001). For peak hip joint flexion angle there was significant decreases between intensities (90% 1RM < 60% 1RM) only to without knee wraps condition (P=0.009), and there was greater knee flexion without knee wraps for both intensities: 60% 1RM (P<0.001) e 90%1RM (P=0.018). For normalized vertical barbell displacement, there were significant differences between intensities when using knee wraps (P=0.022). There were significant differences in RPE between 60 and 90% 1RM for each condition: with knee wraps (P<0.001), and without knee wraps (P<0.001). In conclusion, the use of knee wraps results in decreased muscle activation of the VL at the same intensity (90%1RM).
J Strength Cond Res. 2015 Mar 10. KINEMATIC AND sEMG ANALYSIS OF THE BACK SQUAT AT DIFFERENT INTENSITIES WITH AND WITHOUT KNEE WRAPS.
J Strength Cond Res. 2015 Mar 10. KINEMATIC AND sEMG ANALYSIS OF THE BACK SQUAT AT DIFFERENT INTENSITIES WITH AND WITHOUT KNEE WRAPS.