Movement Patterns of the Lumbar Spine and Sacrum During the Back Squat

Study Title: The Lumbar and Sacrum Movement Pattern During the Back Squat Exercise
Authors: MR McKean, PK Dunn & BJ Burkett
Journal: Journal of Strength & Conditioning Research
Date: October 2010

Summary:

• Here is a recent article that takes a deeper look at the obvious. McKean and colleagues utilized thirty upper year personal training students and personal trainers to examine 1) the timing and range of movement of the lumbar and sacral regions and 2) the influence of stance width, gender, and ascent / descent phases during the back squat exercise. Incorporating no load and 1.5 x body weight loaded trials, measurements from 3-D tracking devices placed on the above regions were evaluated for maximum lumbar and sacrum angles, the time at maximum lumbar and angles, maximum lumbar flexion angles, and the time at maximum lumbar flexion angles. Unsurprisingly, it was revealed that both men and women achieved a deeper squat position with wider stance (twice ASIS width) versus narrow stance (equal to ASIS width) positions. For those interested in the technical rationale, the reasoning behind this was lower maximum lumbar, sacrum and lumbar flexion angles leading to the ability to maintain more upright lumbar spine positions. Men and women, however, differed in movements and timing of maximums where men achieved maximum sacral angles sooner for both the ascent and descent phases of the squat in comparison with women who achieved earlier maximum lumbar angles in both phases. As a result, this modification in sacrum position and timing in men appears to allow them to accommodate for the known gender differences in pelvic girdle morphology. From a safety perspective, the above differences between the narrow and wider stance positions allow the lumbar spine to maintain a more upright position decreasing the load on the posterior structures of the spine.  That said, kyphosis of the lumbar spine does occur during the deep squat although measurements were not collected beyond ASIS width.

McKean MR et al. (2010). The lumbar and sacrum movement pattern during the back squat exercise. Journal of Strength and Conditioning Research, 24(10); 2731-2741