I’ve been using the isometric mid-thigh pull extensively since I was first exposed to it as a master’s student. It is a useful test for evaluating strength and rate of force characteristics in athletes. Most of the variables obtained from the test are reliable, both within a session and between multiple sessions, and the majority relate well to a variety of dynamic (i.e. not isometric) skills, such as the countermovement jump and change of direction.
Unfortunately, there is a lot of variability within research about the optimal body position to use during the pull. Most of the research out there uses a very upright position- the seminal paper on the topic, Haff 1997 (link), specifically stated that the position used for the test was meant to represent the second pull of the clean, which is where the highest forces, accelerations, and velocities are generated during a clean and snatch. Before we go any further, here’s a quick review of the major phases of the clean and snatch:
Notice how upright the lifter is in the third frame at the start of the second pull? That’s the position that the IMTP is supposed to replicate. As far as I know, all of the initial research (definitely the work that was done by Haff, Stone, et al., which is who taught me to use the test) uses this upright body position. Somewhere along the way, a bent over position was introduced in a few different studies. I don’t know how or why it started, but it did.
In 2015, Comfort et al. (link) published a paper that evaluated what effect the use of different body positions would have on how you did the IMTP. He and his group looked at a variety of different knee (120°, 130°, 140°, 150°) and hip angles (125° and 145°), having noticed the discrepancy in the literature in what body position was being advocated for. They found that there was no difference in the forces (whether in the early time periods or in peak force) between different body positions. When this came out, I was surprised. Comfort’s findings went against what I found in my thesis (powerlifters generate more force in an upright IMTP position than they do in a bent over, deadlift-specific position), as well as what weightlifting literature had suggested (the highest forces exerted against the ground and bar are generated when your torso is upright, in the second pull).
In response, as part of my dissertation, we replicated his study and found that an upright position (125° knee and 145° hip) allowed lifters to generate higher forces than a bent over position (125° knee and 125° hip). The difference was especially pronounced when weightlifters used the upright position- they had much higher forces in the upright position than in the bent position. Resistance trained subjects with little weightlifting experience had a difference between positions, but not as substantial.
The moral of the story is that the body position that you use in the IMTP matters- based on the findings of these studies and the already existing biomechanical studies on weightlifting, the upright position is the most advantageous body position for maximizing force production, both in early and late time points. The upright position is probably the one we should be using.
Read on for more:
Beckham, G. K., Sato, K., Santana, H., Mizuguchi, S., Stone, M. H. (2018). Effect of Body Position on Force Production During the Isometric Mid-Thigh Pull. Journal of Strength and Conditioning Research 32(1) 48-56. PDF