The Effect Of Stance On Muscle Activation In The Squat

The squat is a complex push compound weighted lift involving the ankle, knee, and hip joints, which measures the lower body and trunk strength. Due to its multi-joint nature it can be referred to as the pillar of strength for lower body Lombardi (1989). Therefore, any form of squat exercise is a solid foundation in any strength program.  Primary muscles which are strengthen are; erector spinae, glutes maximus, quads group and Hamstrings group.  The secondary muscles are: transverse abdominus, gluteus medius/minimus, adductors, soleus, gastrocnemius. Olympic lifters and powerlifters have often trained different stances in the squat to alter muscle activation; changing joint position can alter the line of pull of the muscles. ( Riley et al. , (2007) and ( Signorile et al., (1995 ) , altering the natural length tension relationship of the muscle (Brughelli et al., 2007) . The squat exercise can increase mobility, strength and power.  The squat strengthens the posterior chain for every day’s life activities.

McCaw and Melrose in (1999) looked at six muscles around the hip and knee EMG activity through different foot stances and loads. There was an increased in adductor longus contraction 50% more in the ascent phase in a wide stance. Adductor longus contraction was 20% greater in the ascent phase than a narrow and shoulder width stance. In addition there was a higher gluteus maximus activation with a further stance width and even further with a higher load. “Regardless of the stance width used, the mean IEMG values were not significantly different for any of the three components of the quadriceps muscle’’. McCaw and Melrose (1999) the only change in quadriceps activity was with a heavier load, although no significant difference between the stances. The difference of a load from 60% to 75% does have a significant aspect of higher IEMG reading of 20 % across the three stances Signorile, et a,.l (1994) . From both studies there seem to be no correlation to isolate an individual quad muscle.

Boyden et al., (2000) found no significance difference in muscle activation of individual quads muscle whilst changing foot positioning. The foot angles used were: 10 degrees inward, neutral, 10 degrees outward and 20 degrees outward. The weight restrictions used were 65% and 75% for 3 reps of the six experience lifters 1rm.

However, Arnold Schwarzenegger’s Encyclopaedia of Modern Bodybuilding, claims that that “the lateral anterior thigh muscle (vastus lateralis) is more active when the lifter adducts the thighs to a narrow stance. The final claim regarding leg position is that overall thigh development takes place when the lifter is using a shoulder width stance and the legs are laterally rotated from the sagittal plane’’ (Schwarzenegger, et al. , 1985). This position is more akin to a powerlifting variation of the back squat. According to Holmans Home Gym Handbook A complete Guide to Training, to  activate the highest contraction of the vasteus medialis, the feet should be laterally pointed out at shoulder width.

In the study by Paoli et al ,.( 2009), six trained experienced lifters completed 3 set sof 10 reps of the back squat, with 3 stances width and three loads ranging from 0-70% of participants 1rm, with a rest of six minutes between sets. The results were that quads or hamstring activation didn’t change through the different stances, as observed in different studies. However, gluteus maximus had greater muscle firing in a wider stance.  This was further reinforced in a wide stance “with the bar load at 70% 1RM, the activation of this muscle recorded  greater than EMG activity of the gluteus maximus was higher than at 100% ’’ (Paoli et al,.  2009).  Paoli also confirms that a traditional squat requires more hip flexion compared to a non traditional squat which is what leads to greater gluteus maximus activation.

From the researched studies McGaw and Melrose, Signoralie and Paoli the greatest impact on muscle activation is of the bar load rather than foot placement or stance width. The squat position will depend where is most comfortable, as there was significant increase in quad and hamstring activation through stance width. The anatomical make up of the quadriceps muscle relate to the IEMG trials there would be little significant increase in quad activation between the stances.  “The vastus medialis and vastus lateralis are uniarticular muscles, crossing only the knee joint, varying stance width by altering thigh position in the frontal plane would not affect the length of the muscles, a factor that could influence recruitment patterns and magnitudes’’ (McGaw and Melrose 1999).

People may prefer to the narrow stance squat as they believe that will have greater correlation to the stance used for jumping or running. The stance position should mimic the athletic position a person wants to achieve, for example feet position should be the same for front squat as your clean and back squat should be the same as your jumping position. The Close stance does allow for the “gastrocnemuis contraction to be greater 21% greater than a wide stance’’ (Escamilla et al., 2001. Furthermore in the close stance squat, the quads and hamstring groups have no further activation.

To achieve more muscle firing and a greater load to be lifter the wide stance is the desired stance. Firstly there is more activation of the main hip extensor the gluteus Maximus. This will achieve greater hypertrophy of the posterior chain fin a shorter period of time. In addition, for a powerlifting competition goal is to lift as much as physically possible, this is easier achieved when you’re recruiting more muscles and fully supported by Beardsley (2013).

References

Beardsley, C .(2016) How does stance width affect muscle activity in Squats?http://www.strengthandconditioningresearch.com/perspectives/vastus-medialis-squats/ [accessed 28 May 2016].

Brughelli M, Cronin J. Altering the length-tension relationship with eccentric exercise implications for performance and injury. J Sports Med 37(9): 807-826, 2007.

Escamilla, R.F., Lander, J.E., Garhammer , J. and 2000, (2000) Biomechanics of powerlifting and weightflifting exercises. In: Exercise and Sport Science.. (Garrett, WE and Kirkendall, DT ed.) Philadelphia: Lippincott Williams and Wilkins.

Holman, S. (1990) Ironman’s Home Gym Handbook: A Complete Guide to Training at Home. Los Angles: Homebody Productions.

Lombardi, V. (1989). Weight Training. Dubuque, IA: W.C. Brown. 201-204.

Mccaw, S. Melrose, D. (1999). Stance width and bar load effects on leg muscle activity during the parallel squat. Medicine and science in sports and exercise. 3 (3), 428-36.

Riley ZA, Terry ME, Mendez-Villanueza A, Litsy JC, Enorka RM. Motor unit recruitment and bursts of activity in the surface electroyogram during a sustained contraction. Muscle Nerve 37: 745–753, 2007.

Paoli, A, Marcolin, G, and Petrone, N. The effect of stance width on the electromyographical activity of eight superficial thigh muscles during back squat with different bar loads. J Strength.

Signorile JF., Kacsik D, Perry A, Robertson B, Williams R. The Effect of knee and foot position on the electromyographical activity of the superficial quadriceps. Orthop Sports Phys Ther 22(1): 2-9, 1995.

Schwarzenegger, A. Dobbins, B. (1985). The Arnold Schwarzenegger Encyclopadia of Modern Bodybuilding. New York: Simon and Schuster, Inc. 461-463.