Effect of rocker shoes on plantar pressure pattern in healthy female runners
Introduction
Forefoot overuse injuries such as metatarsal stress fractures and metatarsalgia are fairly common in the athletic population, especially in runners [1], [2], [3]. A potential cause of these injuries is excessive plantar pressure in the forefoot region [4], [5], and reducing plantar pressure in this region might be an effective treatment [6], [7], [8], [9]. This treatment goal may be achieved with shoes having a stiffened rocker profile (further called as rocker shoes) with the apex positioned proximal to the metatarsal heads [10] (Fig. 1). The unloading mechanism of the forefoot region due to rocker shoes is not fully understood. Factors such as the restricted motion at the metatarsophalangeal joint and the shorter loading time at the forefoot during the propulsion phase of gait are thought to be the main mechanisms [7], [11], [12].
The efficacy of rocker shoes in reducing plantar pressure loading in the forefoot region has been well documented in walking for both healthy individuals and patients with forefoot problems such as metatarsalgia [7], [11], [13], [14], [15], [16]. So far, two studies have investigated the effects of rocker shoes on running biomechanics. The focus of these studies has been on the kinetics, kinematics and lower limb muscular activity in response to rocker shoes [17], [18]. To date, there have been no studies that have investigated the effects of rocker shoes on the plantar pressure pattern during running. More information in this regard gives a better understanding of the capability of rocker shoes to reduce forefoot plantar loading during running which might give direction to alternative prevention and treatment options for foot overuse injuries.
Therefore, the purpose of the current study was to examine the effect of rocker shoes on the foot plantar pressure in running. A sample of healthy female runners was chosen because a higher incidence rate of overuse injuries is reported for females [19], [20], [21]. We hypothesized that during running, the rocker shoes would significantly reduce forefoot plantar pressure when compared with standard running shoes. Secondary outcome of this research was shoe comfort, since this factor might influence the regular use of footwear.
Section snippets
Participants
In this study, female runners were recruited from local running clubs. To be eligible, female runners needed to be between 18 and 50 years old, run at least twice per week and at least five km per run, and be healthy with no history of injuries to the back or lower limb. The experimental protocol of this research was approved by the local Medical Ethics Committee (METc 2012.014).
Shoe conditions
In this study a standard running shoe was used as the baseline condition (Fig. 1A). Another pair of these shoes (same
Results
Eighteen female endurance runners between 19 and 31 years participated in this study. The demographic information (mean ± standard deviation) was as follows: age = 23.6 ± 3 years, height = 171.5 ± 6 cm, and weight = 61.7 ± 7 kg.
The mean and 95% confidence intervals for each outcome measure and the result of statistical comparisons between the two shoe conditions are presented in Table 1. The analyses showed no significant order effects for any of the parameters. There was no difference between two shoe
Discussion
To the best of our knowledge, this is the first study that examined the plantar loading patterns in response to a rocker shoe design in running. As hypothesized, the plantar loading in the forefoot region was reduced considerably by the rocker shoes. PP, MMP, and FTI were significantly reduced in the central and lateral forefoot during running with rocker shoes. MMP and FTI were also reduced significantly in the medial forefoot when running with rocker shoes. The reduction in PP in the forefoot
Conclusion
In conclusion, the current study provide initial evidence that the shoes with a stiffened rocker profile, with the apex positioned proximal to the metatarsal region, significantly reduce the forefoot loading in running. Therefore, rocker shoes might be beneficial for runners who are recovering from metatarsalgia or stress fractures of the forefoot region. However, a load transfer to the heel region may be present as a side-effect. Moreover, running with rocker shoes was less comfortable than
Conflict of interest
The authors have no conflict of interest in this work.
Acknowledgments
No sources of funding were used to assist in the preparation of this article. The authors would like to thank graduate students of the Sports Field Lab, School of Sports Studies, Hanze University of Applied Sciences, and also the runners who participated in this study.
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