Background: The knee wraps (KW) are typically worn to gain mechanical advantage, increase the performance during the back squat (BS). This mechanical advantage (~22%), results from
the energy stored in the KW when tensioned (eccentric phase of BS), transferred to the knee and helping in the extension (concentric phase of BS) known as carry-over. However, the use of KW may affect
the execution of the BS changing the pattern of movement and muscle activation. Therefore, the purpose of this study was to measure the muscle activation during the BS with and without KW at different
Methods: Fourteen trained-men with at least one year’s training experience volunteered to participate in the study (age: 24±4 years, height: 176±6cm, body mass: 81±11kg, BS 1RM:
107±30kg). The experiment was performed in two sessions. During the first session, the maximal BS strength (1RM) was evaluated (without KW), followed by a familiarization with the use of KW. In the
session two, all subjects performed 1 set of 3 repetitions (self-selected cadence) under 4 different conditions in a random order: with KW and without KW (NW) at 60% and 90%1RM. A rest period (10
minutes) was used between conditions. The descent phase was parallel to the ground (~90º of knee joint flexion). The spiral wrapping technique was used. For the muscle activation evaluation, the
superficial electromyography (sEMG) technique was used on vastus lateralis (VL) and gluteus maximus (GM), only in a dominant lower limb. The IEMG was calculated from the sEMG data (normalized by
maximum voluntary isometric contraction, MVIC) during each trial. A repeated-measured ANOVA was used for all dependent variables ((wraps x intensity). Post hoc comparisons were performed with the
Bonferroni’s test. An alpha of 0.05 was used.
Results: Results: For muscle activity, there were significant decreases in the VL for NW at 60%1RM (P= 0.013) and a significant increase NW at 90%1RM (P= 0.037).
There was a significant increase in VL at 90%1RM, when compared with 60% 1RM (KW: P=0.001, ES=1.51 and NW: P<00.001, ES=1.67). There was a decrease in GM for NW only at 60%1RM (P=0.014). There was a
significant increase in GM muscle activity at 90%1RM, when compared with 60%1RM (KW: P<0.001 and NW: P<0.001).
Conclusions: Conclusions: In conclusion, the use of KW may decrease the muscle activation of the VL at high intensities (90%1RM).