(19) PEAK EMG ACTIVATION IS NOT AUGMENTED IN THE GLUTEUS MAXIMUS AND RECTUS FEMORIS MUSCLES WITH VARIATIONS IN BACK SQUAT EXERCISES

Friday, July 12, 2024

12:30 PM – 12:00 PM East Coast USA Time

Location: Exhibit Hall

Poster Presenter(s)

Katelyn G. Kolodziejczyk

Undergraduate Student, Human Performance Lab
University of Mary Hardin-Baylor
College Station, Texas, United States

Author(s)

JD

Jaci Davis

Assistant Director, Human Performance Lab
University of Mary Hardin-Baylor
Belton, Texas, United States
AF

Alyssa Faterkowski

Undergraduate Student, Human Performance Lab
University of Mary Hardin-Baylor
Belton, Texas, United States
Nikolas Keratsopoulos

Graduate Assistant, Human Performance Lab
University of Mary Hardin-Baylor
Cameron, Texas, United States
MR

Mathis Rollin

Undergraduate Student, Human Performance Lab
University of Mary Hardin-Baylor
Belton, Texas, United States
RM

Robert Mills

Undergraduate Student, Human Performance Lab
University of Mary Hardin-Baylor
Belton, Texas, United States
JW

Jayden Widener

Graduate Student
University of Mary Hardin-Baylor
Belton, Texas, United States
CF

Christine M. Florez

Graduate Part-time Instructor
Texas Tech University
Lubbock, Texas, United States
Lem Taylor, PhD

Professor & Director, Graduate Studies of Mayborn College of Health Sciences
University of Mary Hardin-Baylor
Belton, Texas, United States
MP

Mandy Parra

Assistant Professor & Director, Human Performance Lab
University of Mary Hardin-Baylor
Belton, Texas, United States

Abstract Details:

Background: Barbell back squat is used in a variety of settings including strengthening the quad and gluteus muscle groups. Modern advances in Electromyography (EMG) can detect changes in muscle activation at varying loads yet further research is needed to compare muscle activation in different variations of a back squat with a relative load.

Purpose: To compare muscle activation of the gluteus maximus (GM) and rectus femoris (RF) in different back squat variations including barbell back squat (BS), safety bar squat (SS), and barbell with chains (CH).

Methods: Sixteen healthy male and female subjects with at least 1 year of resistance training experience who perform barbell back squats at least once a week volunteered to participate in this study. Data was filtered to only include subjects with complete contraction EMG details (n=10; 23 ±5.5 years; 168.37 ± 14.099 cm; 75.79 ± 14.21 kg) 5 males and 5 females. This study consisted of 2 testing sessions. For all sessions, EMG bi-polar electrodes were placed over the GM and RF. In session 1 a 1 repetition maximum (1RM) was established on barbell back squat according to NSCA guidelines. Session 2 consisted of a 5-minute warmup on a stationary bike, a dynamic warm up, and three sets of different variations of squats performed at 80% of their 1RM. The squat variations included the barbell back squat, a barbell back squat with chains (40 lbs. total), and safety squat bar in a randomized order with 5 minutes of rest between each set. Data was processed via Delsys software using EMGrms. All contractions were normalized to their respective 1RM BS activation. A 2x3 (muscle x variation) ANOVA was run to analyze differences with p-value set at 0.05.

Results: There were no significant main effects or interactions between back squat variations (p = 0.76) and muscle groups (p=0.42). Peak EMGrms for GM were BS (87.29 ± 21.6 mV), CH (82.21 ± 23.42mV), and SS (96.08 ± 29.16 mV). Peak EMGrms for RF were BS (101.89 ± 55.73mV) CH (97.04 ± 50.41mV) SS (94.34 ± 55.25mV).

Conclusions: This data indicates that there are no differences in peak activation of the GM and RF during a set at 80% of 1RM on traditional barbell back squat vs. a safety bar squat and a back squat with chains. Despite these findings’ EMG analysis beyond just a peak EMG should be explored. Increased sample size to analyze these findings with sex differences, fatigue throughout a 10RM, or effects of variations body composition on EMG signal acquisition would be of interest in further studies. PRACTICAL APPLICATIONS: Practitioners can use these findings and implement different variations of the back squat into programs to elicit similar activations in the GM and RF.

Acknowledgements: I would like to thank the participants for devoting their time to complete this study.