title: The influence of insoles with a peroneal pressure point on the electromyographic activity of tibialis anterior and peroneus longus during gait.
abstract: BACKGROUND
  Peroneus longus acts as a foot evertor and pronator, thus ensuring stability of the talocrural joint by curbing inversion movement of the rearfoot. Increased activation of the peroneus longus muscle in the stance phase could have a stabilising effect on the ankle joint. This study aimed to determine whether the activity of the peroneus longus muscle could be increased by the targeted use of a specially formed lateral pressure element in a customised orthopaedic insole.
  
  
  METHODS
  This was a laboratory-based study that utilised a randomised crossover design. Thirty-four healthy participants walked along a walkway in neutral footwear wearing a control insole or a sensorimotor insole with a lateral pressure point adjacent to the tendon of the peroneus longus muscle. The electromyographic muscle activity of the peroneus longus and tibialis anterior muscles was measured using surface electromyography. Contact with the ground was recorded via two pressure sensors under the sole of the shoe. Muscle activity during the stance phase was analysed in the time and amplitude domains and compared statistically with paired t-tests for both insole types.
  
  
  RESULTS
  In 27 out of the 34 participants, an additional activity peak of the peroneus longus muscle was observed in the loading response phase with the sensorimotor insole, which reached its maximum at 29.7 % (±4.5 %) of the stance phase. When averaged over all 34 participants, the integrated electromyographic output for the peroneus longus in the mid-stance phase revealed a significant higher activity (p < 0.001, post hoc power = 0.98, effect size: Cohen's d = 0.71) with the sensorimotor insole (18.1 ± 11.3 % MVCs) than with the control insole (11.2 ± 7.7 % MVCs). No significant effects were established for the other gait phases or for the tibialis anterior.
  
  
  CONCLUSIONS
  An increase of muscle activity of the peroneus longus muscle was observed during the loading response and mid-stance phase, when orthopedic insoles with a lateral pressure point were worn. We conclude that the pressure point changes afferent information and leads to an increased peroneus longus activation in the time interval in which the pressure point exerted pressure on the peroneal tendon.
authors.affiliation: Sportwissenschaftliches Institut, Universität des Saarlandes, Campus Geb. B 8.1, 66041 Saarbrücken, Germany.
authors.forename: Oliver
authors.initials: O
authors.lastname: Ludwig
authors.affiliation: Chirurgisch-orthopädisches Versorgungszentrum, Rathausstrasse 2, 66557 Illingen, Germany.
authors.forename: Jens
authors.initials: J
authors.lastname: Kelm
authors.affiliation: FG Sportwissenschaft, Erwin-Schrödinger-Strasse, Gebäude 57, 67663 Kaiserslautern, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Fröhlich
mesh_terms: D000293:Adolescent; D000328:Adult; D000886:Anthropometry / Q000379:methods; D018592:Cross-Over Studies; D004576:Electromyography / Q000379:methods; D004867:Equipment Design; D005260:Female; D061826:Foot Orthoses; D005684:Gait / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000502:physiology*; D011312:Pressure; D012775:Shoes; D016474:Weight-Bearing / Q000502:physiology; D055815:Young Adult
keywords: Foot orthoses; Gait; Orthotic insoles; Sensorimotor feedback; Surface electromyography