(8) DIFFERENCES IN MUSCLE ACTIVITY BETWEEN THE FRONT AND BACK SQUAT DURING A RAMPING THREE REPETITION MAXIMUM TESTING SESSION.

The back squat (BS) is a primary movement when training lower body muscles across all levels of athletes and is considered a vital component in strength training for athletes to improve muscle growth and power development because of the large activation of major muscle groups. Two squat variations that are commonly performed are the BS and front squat (FS). Muscle activation using surface electromyography (EMG) signals is commonly measured and quantified by researchers as a way to help practitioners make informed decisions regarding exercise selection.

Purpose: The purpose of this study was to compare peak and mean surface electromyography (EMG) signal levels of the gluteus maximus (GM), vastus lateralis (VL), vastus medialis (VM), and trapezius ascendens (TA) of the FS and the BS in resistance trained individuals.  

Methods: Surface electromyography (EMG) was used to measure muscle activity of the GM, VL, VM, and TA during both the FS and BS. The data analyzed were taken from a larger data collection set and included 4 male and 7 female participants (M + SD: n =11; age: 27.45 ± 7.89 years; height: 174 ± 10.11 cm; body mass: 79.43 ± 15.36 kg; BS 3RM: 115.45 ± 62.82 kgs; FS 3RM: 77.5 ± 33.03 kgs). Participants completed two testing sessions in the same day, one BS and one FS. In both sessions, participants completed 3RM testing (used for normalization) and 50 and 70% values were taken from sets leading up to the participants 3RM (all with within ± 10%) and are representative of 50 and 70% of the participants 3RM. This study design was meant to reflect a typical ramping training session protocol where an athlete would work up to a 3RM. Peak and mean muscle activity between the FS and BS were analyzed using 12 paired sample t-tests for both the peak and mean muscle activity data.

Results: Significantly greater peak muscle activity in the was seen in the TA during the FS than the BS at 3RM (t(10) = -2.34, p = 0.04)). Additionally, significantly greater mean muscle activity occurred in the TA during the FS at all loads: 50% 3RM (t(10) = -2.25, p = 0.048)), 70% 3RM (t(10) = -3.78, p = 0.004)), and 3RM (t(10) = -4.79, p < 0.001)). The only other significant difference occurred in the VM at 50% 3RM (t(10) = 2.29, p = 0.04)).

Conclusion: The TA is typically regarded as a stabilizing muscle during most movement patterns and the FS provided greater muscle activity in the TA then back squat. This result likely occurred because of the bar placement during the FS demands a more upright posture and greater mid-back stabilization then the BS. PRACTICAL APPLICATIONS: Prescribing a FS instead of a BS may promote greater activity of musculature which stabilizes the mid and upper back. When programming for sports requiring upright postures and mid to upper back strength and stabilization, it may be beneficial to utilize a FS opposed to a BS. 


Acknowledgements: ACKNOWLEDGEMENTS: Thank you to Oro Muscles for your contribution to the data collection and analysis.