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Athletic development specialists dedicated to the art and science of excellence in movement

Single Leg Stance and Gait Stability

Running is complex gait pattern but can be distilled into high repetition single leg stance.  Further, the ability of the young human to balance on one leg is a critical motor milestone that retains importance at all ages.  Modern biomechanics has given us tools to break down movement with painstaking detail.  But despite this detail, we must never stray from the basics, one of which is supporting the body on one leg. 

One way to explain single leg stance for running with stride WIDTH.  Stride length has been a hot topic in running, but step width gets little attention outside the academic community.  The importance of step with is easy to understand….put your feet close together; then spread them wider.  Which offers the greatest support?  The wider stance, quite obviously.   Now, there may be performance consequences by going TOO wide, but a wider stance is generally more supportive.  A wider step width in gait is simply a dynamic form of balance control.

The narrowest of step widths is standing on one foot, (other than for dancers who balance on their toes; see Skill Development and Footstrike: What Runners Can Learn from Dancers).   The literature is clear that single leg stance is a valid postural test.  The importance of single leg stance may also lead us to rethink how arm carriage is coached.  Arrellano (2102) found,  “while eliminating arm swing increased the energetic cost of running overall, arm swing does not appear to assist with lateral balance. Our data suggest that humans use step width adjustments as the primary mechanism to maintain lateral balance during running.”

Step width has also been shown to correlate with ilotibilial band (ITB) strain by Meardon (2012):

  • "Greater ITB strain and strain rate were found in the narrower step width condition. 
  • ITB strain was significantly greater in the narrow condition than the preferred and wide conditions and it was greater in the preferred condition than the wide condition.
  • ITB strain rate was significantly greater in the narrow condition than the wide condition.” 

Though I might disagree with the author’s suggestion to consciously alter stride, this study remains useful.  Some have described running as a series of controlled falls…”falling” with a wider stance may be a subconscious way to compensate for poor single leg balance. (See also Thoughts on IT Band Syndrome

Prioritizing single leg stance also has training implications.  Takacs (2012) observed that “hip muscle strengthening interventions have failed to find significant reductions in frontal plane loading measures such as the external knee adduction moment with altered hip strength.”  During a single leg stance test, authors observed that pelvic drop and trunk lean during single leg stance were predictive of knee adduction (knee caving in).   In short, chasing isolated hip strength may actually distract from a balance issue.   

Conclusion
As in many cases, the simplest fix is often most effective.  We’ve written countless times arguing against run form coaching, instead choosing to prioritize corrections to fundamental movement patterns.  The goal is to improve the body at a fundamental level first, before loading the athlete with specific cues that mostly serve as band aids for underlying dysfunctions.  Common sense interventions like brushing your teeth while standing on one foot, or surreptitiously balancing on one leg while at work or in line at a store are other ways to easily “sneak in” these improvements.  However you address the issue with exercise or treatment, ensure that single leg stance is part of the locomotor evaluation.  

References

Meardon SA, Campbell S, Derrick TR.  Step width alters iliotibial band strain during running.  Sports Biomech. 2012 Nov;11(4):464-72.

Arellano CJ, Kram R.  The energetic cost of maintaining lateral balance during human running.  J Appl Physiol. 2012 Feb;112(3):427-34. doi: 10.1152/japplphysiol.00554.2011. Epub 2011 Nov 3.

Takacs J,Hunt MA.  The effect of contralateral pelvic drop and trunk lean on frontal plane knee biomechanics during single limb standing.  J Biomech. 2012 Nov 15;45(16):2791-6. doi: 10.1016/j.jbiomech.2012.08.041. Epub 2012 Sep 19.

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