Effect of foot orthoses on tibialis posterior activation in persons with pes planus.
OBJECTIVE
To examine the influence of footwear on tibialis posterior (TP) activation in persons with pes planus.


METHODS
Six asymptomatic adults with pes planus (arch index of < or =0.16) participated. Subjects performed a resisted foot adduction with plantar flexion exercise (3 sets of 30 repetitions). The exercise was performed barefoot and shod with foot orthoses. The two testing conditions were separated by a week. Magnetic resonance image signal intensity of the tibialis posterior, tibialis anterior, soleus, medial gastrocnemius, and peroneus longus was measured immediately before and after each exercise. Multivariate analyses of variance followed by paired Student's t-test were performed for the signal intensity of each muscle assessed to determine whether TP was selectively activated during the barefoot and shod exercises.


RESULTS
When barefoot, five of the six subjects activated other lower-leg muscles in addition to TP. When wearing the foot orthoses and shoes, all five participants activated only TP. Additionally, activation of TP was higher when exercises were performed in shoes with orthoses than when barefoot (P = 0.019).


CONCLUSIONS
Wearing the foot orthoses and shoes improved selective activation of the TP in persons with flat feet. In cases where selective activation of TP is desirable, such as persons with flat feet or TP tendon dysfunction, use of shoes and an arch supporting foot orthoses may enhance selective activation of the muscle.
Kulig
Kornelia
K
Department of Biokinesiology and Physical Therapy, University of Southern California, Los Angeles, CA, 1540 E. Alcazar Street, CHP-155, Los Angeles, CA 90033, USA. kulig@hsc.usc.edu
Burnfield
Judith M
JM
Reischl
Stephen
S
Requejo
Susan Mais
SM
Blanco
Cesar E
CE
Thordarson
David B
DB
D000328:Adult; D003430:Cross-Sectional Studies; D015444:Exercise / Q000502:physiology; D005413:Flatfoot / Q000503:physiopathology*; D005528:Foot / Q000503:physiopathology*; D006801:Humans; D008279:Magnetic Resonance Imaging; D015999:Multivariate Analysis; D018482:Muscle, Skeletal / Q000503:physiopathology; D009989:Orthotic Devices