Muscle contributions to support and progression during single-limb stance in crouch gait.
What the Gait Guys have to say about this article:
We have long advocated the use of the “shuffle gait” exercise for increased gluteal activation (see Youtube clip entitled “the shuffle gait exercise”) and this paper provides further support for our recommendation.
Try this simple experiment. Stand on 1 leg. Now close your eyes and try and stay that way for 30 seconds, trying not to lose your balance, touch the ground with your other foot or steady yourself with your hands. Once you have regained your composure, with your eyes closed, extend our head (ie. Look up). Tough to balance, eh? So what just transpired?
3 integrated sensory systems enable us to remain upright in the gravitational plane: vision, the vestibular system and the proprioceptive system (joint/muscle mechanoreceptors). When you 1st stood on one leg, you were utlilizing all 3 systems. When you closed your eyes you were eliminating vision from the equation. When you tilted your head back, you were taking out the lateral semicircular canals from the vestibular system, relying predominantly on the joint and muscle proprioceptors. Let’s guess that you probably need some work on your proprioceptors!
Placing someone in a crouched gait generally means you are at least partially flexed at the waist and need to extend your head somewhat to keep your eyes parallel with the horizon (the brain is wired to keep the visual axes upright and parallel). Extending your neck activates the local joint mechanoreceptors and more importantly, the muscle mechanoreceptors in the suboccipital muscles, which have the highest density of mechanoreceptors of any muscles in the body. These muscle mechanoreceptors feed information into the cerebellum and vestibular nuclei, which fire the antigravity extensor muscles that keep us upright in the gravitational plane. This includes muscles like the glutes, quads and lumbar erectors, just like in the study.
It was interesting that in crouched gait, the muscles which provided upward momentum (gastroc, soleus, quads) remained active throughout single leg stance. These are also stabilizers of the foot and placing the ankle in dorsiflexion (as in a crouch) increases the amount of pronation occurring (remember pronation is dorsiflexion, eversion and abduction); this requires additional stabilization (medial gastroc is an inverter, gluteus Maximus and posterior fibers of glute med control the speed of internal rotation of the lower extremity, along with vastus medialis).
Look to crouched positions as training tools when rehabbing gait, and don’t neglect the shuffle!