Squat stance and thigh muscle activation

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Squat stance and thigh muscle activation

Postby Dtlv74 on Thu Jun 11, 2009 11:46 pm

Stance width and bar load effects on leg muscle activity during the parallel squat.

Applied Sciences
Medicine & Science in Sports & Exercise. 31(3):428-436, March 1999.

Stance width and bar load effects on leg muscle activity during the parallel squat. Med. Sci. Sports Exerc., Vol. 31, No. 3, pp. 428-436, 1999.

Purpose: Altering foot stance is often prescribed as a method of isolating muscles during the parallel squat. The purpose of this study was to compare activity in six muscles crossing the hip and/or knee joints when the parallel squat is performed with different stances and bar loads.

Methods: Nine male lifters served as subjects. Within 7 d of determining 1RM on the squat with shoulder width stance, surface EMG data were collected (800 Hz) from the rectus femoris, vastus medialis, vastus lateralis, adductor longus, gluteus maximus, and biceps femoris while subjects completed five nonconsecutive reps of the squat using shoulder width, narrow (75% shoulder width), and wide (140% shoulder width) stances with low and high loads (60% and 75% 1RM, respectively). Rep time was controlled. A goniometer on the right knee was used to identify descent and ascent phases. Integrated EMG values were calculated for each muscle during phases of each rep, and the 5-rep means for each subject were used in a repeated measures ANOVA (phase x load x stance, [alpha] = 0.05).

For rectus femoris, vastus medialis, and vastus lateralis, only the load effect was significant. Adductor longus exhibited a stance by phase interaction and a load effect. Gluteus maximus exhibited a load by stance interaction and a phase effect. Biceps femoris activity was highest during the ascent phase.

The results suggest that stance width does not cause isolation within the quadriceps but does influence muscle activity on the medial thigh and buttocks.


Kind of backs up what I've felt for a while with squats... that changing the stance does little to isolate the various heads of the quad, but can change the recruitment of the other muscles of the upper thigh (more involvement as the stance gets wider).
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Re: Squat stance and thigh muscle activation

Postby GymBunny on Fri Jun 12, 2009 10:43 am

I repeat I love you Det.
Mens sana in corpore sano
Never look back with regrets and think "what if" for that way madness lies. There are those that will envy you and try and undermine you. They are not worth your time.
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