Many Thanks !! Vesa
Another approach that was
not mentioned in your email is to approach
locomotion from the neurological perspective. It is well described in the
neurological literature that the primary afferent information for
triggering the gait cycle arises from a stretch of the hip flexors
(primarily the iliopsoas). This does not arise from the hip joint
afferents. As the iliopsoas cross the hip, SI, and lumbar spine
limitations in any of these joints will constrain / limit the excursion of
the iliopsoas so the stretch will be minimized. Furthermore, as the muscle
group cross all of the articulations, increasing the extension range at any
of the articulations would have the effect of increasing the stretch on the
iliopsoas - a finding that clinically validates the theories any of the
hip, SI, or lumbar spine therapists.
A second important afferent signal arises from the stretch and tension
receptors in the triceps surae (gastroc and soleus). During terminal
stance, the unweighting of the triceps facilitates the initiation of the
swing phase (facilitates flexors and inhibits extensors); during mid stance
the loading of the limb facilitates extensors and inhibits flexors. (Note
the wonderful reversal of the effects of triceps stretch.)
If the stretch of the posterior calf muscles is decreased then this
facilitation of flexion during terminal stance or of extension during mid
stance is reduced. Specifically, if during mid stance the calcaneus is
allowed to plantarflex, then the stretch of the triceps is decreased. This
calcaneal plantar flexion occurs if the longitudinal arch is allowed to
fall. In terminal stance, if the calcaneus is allowed to maintain its
plantar flexion, the stretch on the triceps remains for a longer time
period which could delay the facilitation of the swing phase.
Viewing locomotion from a neurological control perspective helps to
synthesize the manual therapist and podiatric perspectives. I need to
emphasize that the primary, locomotion-triggering input arises from the
stretch of the hip flexors -- not from the triceps. While this has been
shown in animal research, it is also clinically apparent when working with
bilateral lower extremity amputees who can walk and run (<11 sec for 100m).
This does not negate the importance of the afference from the lower leg,
rather it ranks their relative values -- Primary is hip flexor stretch,
next is the variable stretch of the triceps, and then finally "other"
Perhaps, a patient who is unable to gain enough afference from one source
(either hip or triceps), may compensate by trying to increase the afference
from the other source. If this could be shown, then hip/SI/lumbar
articular problems could give rise to an "over-use" problems of the foot
(and the opposite should hold true as well).
For an in depth discussion of the neurology of locomotion I would
recommend the excellent reviews by Whelan (1996) and Pearson (1995).
Paul D. Hansen, Ph.D.,
Fircrest Physical Therapy
1105 Regents Blvd., Suite C
Fircrest, WA 98466
Pearson KG 1995 Proprioceptive regulation of locomotion.
in Neurobiology 5:786-791.
Whelan, PJ 1996 Control of locomotion in the decerebrate cat. Progress
Neurobiology 49:481-515. (This is my favorite review paper on the
neuroanatomy of locomotion)
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