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Abstract Details

Abstract Title

The Muscle Activity is Affected by Using the Knee Wraps During the Back Squat Exercise at Different Intensities

Abstract Theme

Neuroscience and sport

Type Presentation

Poster

Abstract Authors

Presenter Willy Andrade Gomes - Methodist University of Piracicaba (Program in Science of Human Movement) - BR
Lee E. Brown - California State University (Department of Kinesiology, Center for Sport Performance) - US
Enrico Gori Soares - Methodist University of Piracicaba (Program in Science of Human Movement) - BR
Josinaldo Jarbas da Silva - Methodist University of Piracicaba (Program in Science of Human Movement) - BR
Érica Paes Serpa - Methodist University of Piracicaba (Program in Science of Human Movement) - BR
Daniel Alves Correa - Methodist University of Piracicaba (Program in Science of Human Movement) - BR
Guanis de Barros Vilela Junior - Methodist University of Piracicaba (Program in Science of Human Movement) - BR
Charles Ricardo Lopes - Methodist University of Piracicaba (Program in Science of Human Movement) - BR
Paulo Henrique Marchetti - Methodist University of Piracicaba (Program in Science of Human Movement) - BR

Presentation Details

Poster Exhibition Site (Local): Orange - 2        Date: 2 September        Time: 8am to 7pm        Presenter: Willy Gomes

Abstract Resume

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
intensities.

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).

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