New Research: Isometric versus Regular Barbell Squats

In the last issue of the Journal of Strength and Conditioning Research, we had another paper published, this one based on the isometric squat. This was based off of some separate analysis we did with Caleb Bazyler‘s thesis. You’ve probably already seen some of the stuff I’ve done with the isometric mid thigh pull (IMTP with weightlifters, IMTP with powerlifters). The IMTP is a major research interest of mine (my dissertation is centered on this test), and isometric squats are related to that.

Multijoint isometric testing is something particularly worthwhile in my opinion. Yes, it does need some specialized equipment but it is very fast, very efficient to administer to a lot of athletes, and gives a ton of information that you can’t get just from a 1-RM test. Yes, you get peak force production, which will tell you similar information as a 1-RM, but you also get rate of force development for any time-span you might be interested in, impulse (remember that impulse is what ultimately causes movement to occur- a bigger impulse means a bigger change in momentum) again to any time point, and force at any particular time point. Wayyyy more information in less time than a 1-RM.

Probably the most interesting finding from this paper, in my opinion, is further support for joint angle specificity. We found that peak force generated in an isometric squat at 90 degrees of knee flexion related better than peak force generated at 120 degrees of knee flexion to 1-RM full-range back squat. Basically, if you want to know more about a full range squat- a lower knee angle in an isometric squat relates better to a full range squat.

The opposite is also seems to be true- peak force generated with a knee angle of 120 degrees related better to a concentric only half-squat (100 degree knee angle). A 120 knee angle in an isometric squat relates a little bit better to a partial concentric squat. You can see the correlations in the cropped table from the paper below.

Table from Isometric squat paper

A quick caveat to this though, related to statistics.  We only had 17 subjects, so the confidence intervals for the correlation values were rather wide. Strictly speaking, the confidence intervals for each relationship overlap (the confidence interval of the correlation between 90 degree peak force and 1-RM overlap that of the confidence interval of the correlation between 120 degree peak force at 1-RM). A confidence interval overlap may mean that there isn’t a difference between relationships (that there isn’t any difference in relationship between 90 degree and 1-RM versus 120 degree and 1-RM). Some statisticians have criticized this rule of thumb as overly conservative, so it is a bit hard to say. We can probably chalk up the support of joint angle specificity as weak evidence, if nothing else.

Either way, multi-joint isometric testing has shown its usefulness, yet again.

You can download the paper here:  The use of the isometric squat as a measure of strength and explosiveness