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Pain and Biomechanics in Running: Determining Causation, Part II

On this blog we’ve written several articles on the slippery slope of running form coaching and analysis.  To recap, there is scant evidence (outside of evangelistic anecdote) that conscious changes to form may improve performance.  Though there is evidence to support form modifications to improve injury, the interplay between pain and biomechanics is still widely unsettled.

(See Reasons not to Coach Running Form, Part I, II, III, and IV; Pain and Biomechanics, Part I)

It may surprise athletes that biomechanics are often NOT the driving force behind pain.  Pain CAN be the result of damage (“my X tendon is rubbing on my Y bone causing swelling”) but relationship between pain and symptoms is often non linear.  For example, a 5% improvement in physical measures does not always equal a 5% reduction in pain.  

Two recent studies further illuminated this concept within the running world:

Seeley (2013) addressed this issue with an experimental pain study.  One way to solve the “which comes first?” question in pain vs biomechanics is to experimentally create pain.  If you test injured runners, they are already in pain making it difficult to determine whether pain came before biomechanical changes or whether biomechanical changes caused pain.

In this study, authors created experimental knee pain via a hypertonic saline injection.  Twelve healthy subjects performed running and walking tasks under painful, nonpainful, and “sham” conditions.  After the experimental pain, authors observed significant changes in running peak plantar flexion angle and running peak hip adduction angle, concluding that “increased perceived pain during various human movements and produced altered running and walking biomechanics that may cause abnormal knee joint-loading patterns.”

Implication: Pain may precede changes in biomechanics.  It’s a mistake to assume that altered or “flawed” running biomechanics are the cause of pain.  Certain biomechanical risk factors are well established.  Ineffective loading patterns may indeed relate to one’s pain, but it’s incorrect to assume that biomechanics drive causation in each case.  This position is not to discount the contribution of risk factors.  But as we have said repeatedly, running form is a complex pattern with a great many unknowns that cannot be reduced to isolated technique changes.   

Another recent study (Foch 2013) explored differences between runners who had suffered IT band syndrome and those who had not.  The IT band runners were not presently injured, but all had a history of at least one episode.  Authors tested many biomechanical variables and found the injured runners and

the non-injured runners demonstrated similar results in

  • trunk lateral flexion
  • contralateral pelvic drop
  • hip adduction
  • external knee adduction
  • trunk - pelvis coordination
  • trunk ipsilateral flexion.
  • Lateral core endurance

In sum, many biomechanical factors commonly deemed important could not differentiate between the injured runners and the non-injured runners.  Because there is SOME evidence in other places that these factors may be important, this study alone does not invalidate these factors.  Instead, we are reminded there is still much uncertainty in this area; far too much to justify the myopic trust in running form as an antidote for performance.

Conclusion
The purpose of this article is merely to reinforce concepts that have been previously discussed here and elsewhere.  Though confusion about the true nature of pain exists in all realms, runners are especially quick to latch onto the mechanical explanations of technique being the cause of pain.  There is still much to learn in this area, but we do know that reasons for pain are highly complex and cannot as a rule be linked to any single factor.    

References

Foch E, Milner CE.  Frontal Plane Running Biomechanics in Female Runners with Previous Iliotibial Band Syndrome  J Appl Biomech. 2013 May 13. [Epub ahead of print]

Seeley MK, Park J, King D, Hopkins JT.  A novel experimental knee-pain model affects perceived pain and movement biomechanics.  J Athl Train. 2013 May-Jun;48(3):337-45. doi:10.4085/1062-6050-48.2.02. Epub 2013 Feb 20.

Comments

Dealing with pain

It is strange but true that the ability to feel pain becomes negligible when a person is injured heavily, because it damages the sensory system to a great extent, and that is why we come across the incidences when a badly injured person walks ahead normally to seek help from the others.

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