The effects of enhanced plantar sensory feedback and foot orthoses on midfoot kinematics and lower leg neuromuscular activation Callan Ritchie a , Kade Paterson a , Adam L. Bryant b , Simon Bartold b , Ross A. Clark b, * a Centre of Physical Activity Across the Lifespan, School of Exercise Science, Australian Catholic University, Australia b Centre for Health, Exercise and Sports Medicine, Department of Physiotherapy, Faculty of Medicine, Dentistry and Health Sciences, The University of Melbourne, Australia 1. Introduction Abnormal foot motion or posture has frequently been cited as a risk factor for lower extremity injuries. In particular, research has investigated the association between excessive foot pronation and injury [1,2]. Although pronation is essential for normal locomotion, injury risk may increase when this motion is excessive [2]. For example, excessive pronation has been associated with a number of lower extremity injuries such as plantar fasciitis [3], stress fractures [4] and patellofemoral pain syndrome [5]. As such, much work has been done to establish interventions designed to reduce excessive pronation. One method that has been shown to reduce pronation is foot orthoses [1]. Many studies have indicated that foot orthoses decrease rearfoot eversion angle [6–10], rearfoot eversion velocity [10,11] and ankle and rearfoot inversion moments [10–12]. In addition to orthotic interventions, other work has explored alternative methods of altering lower limb mechanics. One such method involves altering plantar sensation, achieved by either modifying the ability of cutaneous receptors to detect sensation or altering the stimulus level. For example, there is evidence that reducing plantar sensation using ice baths alters plantar pressures [13,14] and muscle activity patterns [14], whilst increasing plantar sensation using a vibrating insole decreases measures of gait variability [15]. Other methods of increasing plantar sensory feedback, through techniques such as sandpaper insoles [16], socks with gravel of differing size and grade glued to the inside of the plantar surface [17], and textured insoles [18–21], have also been shown to alter lower limb mechanical variables. As such, altering plantar sensory feedback might provide a method of improving abnormal mechanical factors known to increase injury risk. To date however, no published studies have explored whether altering sensory feedback during walking reduces abnormal mechanics, such as excessive pronation. Consequently, the aim of this study was to determine if increased plantar sensory feedback can be used to reduce measures of foot pronation during an acute bout of Gait & Posture 33 (2011) 576–581 ARTICLE INFO Article history: Received 6 December 2010 Received in revised form 14 January 2011 Accepted 15 January 2011 Keywords: Pronation Somatosensory Proprioception Biomechanics Podiatry Gait ABSTRACT Excessive foot pronation has been associated with injuries of the lower extremity. No research has investigated the effect of enhancing plantar sensory feedback on foot pronation. The aim of this study was to determine whether a shoe with enhanced plantar sensory feedback reduces midfoot pronation. Midfoot kinematics and electromyography of the peroneus longus, tibialis anterior and medial gastrocnemius of 21 males (age: 21.0  4.0 years, height: 176.8  5.0 cm, mass: 73.3  6.5 kg) were recorded whilst walking in a neutral shoe, a neutral shoe with a prefabricated foot orthotic and a neutral shoe with nodules located on the plantar-medial insole (experimental shoe). Friedman’s ANOVA and Wilcoxon tests were used to evaluate differences between shoe conditions. Mean midfoot-tibia angles during ground contact were significantly more supinated when wearing the experimental shoe (+7.148, p = 0.023) or orthotic (+3.838, p = 0.006) compared to the neutral shoe. During the loading phase, midfoot angles were significantly more supinated when wearing the experimental shoe compared to the orthotic (+5.538, p = 0.008) or neutral shoe (+6.208, p = 0.008). In the midstance phase, midfoot supination was significantly higher in the orthotic compared to the neutral shoe (+2.798, p = 0.006). Finally, supination was increased during the propulsive phase when wearing the experimental shoe compared to the orthotic (+7.438, p = 0.010) or neutral shoe (+10.838, p = 0.009). No significant (p < 0.05) differences in muscle activation were observed. These results suggest that increasing plantar sensory feedback to the medial aspect of the foot reduces midfoot pronation during an acute bout of walking. Further work is needed to explore whether these effects remain over longer time periods. ß 2011 Elsevier B.V. All rights reserved. * Corresponding author at: Department of Physiotherapy, Faculty of Medicine, Dentistry and Health Sciences, The University of Melbourne, Victoria 3010, Australia. Tel.: +61 431737609; fax: +61 3 8344 4188. E-mail address: raclark@unimelb.edu.au (R.A. Clark). Contents lists available at ScienceDirect Gait & Posture journal homepage: www.elsevier.com/locate/gaitpost 0966-6362/$ – see front matter ß 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.gaitpost.2011.01.012