**2.3 Biomechanical aspects of feet for treatment with insoles and shoes in runners with plantar fasciitis**

In an attempt to prevent the progression of plantar fasciitis or even to eliminate the periods of recurrence of the disease, most therapeutic approaches directed to runners with this pathology occur through insoles, with the purpose of supporting the medial longitudinal arch and reducing overload in the rearfoot region, as well as footwear to minimize excessive rearfoot pronation [20]. However, few studies have aimed to understand the effect of these factors on plantar fasciitis [56, 57], especially in running [58, 59].

One explanation for the few studies on treatment with insoles or shoes in runners may be due to the treatment time for plantar fasciitis. According to Young *et al.*, [60]

#### *Biomechanical Aspects of the Static and Dynamic Patterns of the Feet of Runners with Plantar… DOI: http://dx.doi.org/10.5772/intechopen.97090*

the treatment lasts around six to 18 months, a fact which can lead to frustration of the therapist and the patient [61]. Although conservative therapy (drugs, physiotherapy, and orthosis resources) is still the mainstay of treatment, there are several controversies about the effectiveness of the therapeutic program that best provides symptom relief [62]. Thus, when conservative treatment is unsuccessful, a percentage of 5 to 10% of those affected progress to surgical treatment for removal of the plantar fascia [63].

The purpose of most of the treatment strategies for plantar fasciitis described in the literature is to reduce pain symptoms and overloads imposed on the calcaneus. In this direction Landorf *et al.,* [57], evaluated 135 individuals with plantar fasciitis, non-athletes, in a longitudinal follow-up treatment with insoles. The objective was to evaluate the effectiveness of three types of insoles on the plantar surface, after three, six, and twelve months of treatment. The authors concluded that, in the long run, none of the insoles promoted a reduction in symptomatology and improved foot function. This may explain the cycles of relapse and remission of plantar fasciitis [64].

This study is important, since one of the most commonly used resources by runners in their running practice is the insole, as a corrective factor for a better mechanical performance of the feet, as it is low cost when compared to recognized brand footwear in the market. According to some authors [65–67], the support of the longitudinal plantar arch is one of the most common treatments used in the population of athletes with plantar fasciitis.

Another study aimed at conventional footwear in triathlete runners with plantar fasciitis found that many have manufacturing defects that possibly contributed to the development of plantar fasciitis. Evaluating the construction of sports shoes (in terms of flexibility and the sole) can prevent injuries from overuse of the lower extremities [58].

In another study, the authors aimed to verify the effect of traditional footwear in relation to footwear with an ultra-flexible intermediate midsole (Nike 5.0) for the treatment of chronic plantar fasciitis associated with diverse exercises for 12 weeks and a 6-month follow-up after intervention. The conclusion of this study revealed that the shoes with an ultra-flexible intermediate midsole (Nike 5.0) promoted pain reduction earlier than conventional shoes [59].

Given the biomechanical studies carried out to date, it is likely that the way the loads are distributed on the surface of the feet of individuals with plantar fasciitis is different depending on the type of insole and footwear used by runners, especially when considering the acute and chronic phase of the pathology. However, there is still a scarcity of studies that address the effects of footwear and insoles on heel pain in runners with plantar fasciitis and their relationship with the plantar arch and load imposed on the feet during running and static postures.
