The influence of motion control shoes on the running gait of mature and young females

Abstract

Background

This study compared the running gait of mature and young females, and investigated the effect of a motion control shoe. First, it was hypothesised that in a neutral shoe, mature females would display significantly greater rearfoot eversion, knee internal rotation and external adductor moments when compared to a younger group. Secondly, the motion control shoe would reduce rearfoot eversion and knee internal rotation in both groups. Thirdly it was hypothesised that the motion control shoe would increase knee external adductor moment, through an increase in knee varus and moment arm.

Methods

15 mature (40–60 years) and 15 young (18–25 years) females performed 10 running trials at 3.5 m s⁻¹ ± 5% over a force platform. Two shoes were tested, the Adidas Supernova Glide (neutral), and the Adidas Supernova Sequence (motion control). Ankle and knee joint dynamics were analysed for the right leg, and the mean of ten trials was calculated. Joint moments were calculated using inverse dynamics.

Findings

In the neutral condition, mature females presented greater peak rearfoot eversion, knee internal rotation, and external adductor moments than young females (p < 0.05). A motion control shoe significantly reduced peak rearfoot eversion and knee internal rotation among both groups (p < 0.05). No between shoe differences in knee external adductor moment were observed.

Interpretation

A motion control shoe is recommended to reduce risk of injury associated with rearfoot eversion and knee internal rotation in mature females. However since the knee external adductor moment is a variable commonly associated with medial knee loading it is suggested that alternative design features are required to influence this moment.

Introduction

It is widely acknowledged that participation in running as a recreational or competitive activity contributes positively to health and fitness outcomes [1]. However, this activity is also associated with high rates of musculoskeletal injury, evidenced by a study reporting one running injury to occur every 100 training hours [2]. Among the twenty-six most common conditions to affect runners, women have been shown to have higher incidences of patella femoral pain syndrome, iliotibial band friction syndrome, plantar fasciitis, meniscal damage and pathology of the patella, Achilles tendinopathy and osteoarthritis of the knee compared to men [3]. Increased age, specifically >50 years, has also been found to be associated with a higher incidence of overuse running injuries [3]. The higher incidence of running related overuse injuries in women compared to men, and in runners over the age of 50 years indicates that mature female runners are particularly susceptible to injury occurrence.

Mature female runners have been found to yield significantly greater magnitudes of rearfoot eversion, knee internal rotation, knee external adductor moment and peak loading rate (of vertical ground reaction force) compared to younger runners [4]. While this study did not control for footwear, these age-related changes in female running gait may indicate biomechanical risk factors for overuse injury development and progression of degenerative conditions. Footwear provides an accessible method for changing patterns of running gait [5]. Thus investigation of the influence of footwear manipulation on mature female running gait is important in order to investigate the potential for reducing biomechanical risk factors associated with overuse injury and degenerative conditions that may be exacerbated by regular participation in running.

Motion control aspects of a shoe aim to reduce excessive rearfoot motion and subsequent internal rotation of the lower leg and knee valgus, through altering deformation rates and geometry between the medial and lateral sides of the shoe [6]. Although a magnitude of rearfoot eversion is essential to produce a flexible forefoot to enhance shock absorbency and allow adaptation to irregularities in the running surface [7], excessive movement has been frequently associated with certain running-related overuse injuries [8]. Excessive rearfoot motion is suggested to increase knee pain and overuse injury risk via elevated levels of lower limb strain [9], increased knee internal rotation and a forefoot loading [10], [11], [12]. Studies investigating the ability of greater medial support in footwear to reduce rearfoot eversion and lower leg internal rotation during running, have found promising results [13].

However, a negative effect of motion control shoes has been an increase in knee external adductor moment during running [14]. High values of this moment are related to increased loading of the medial knee [15], and are primarily contributed to by the frontal plane moment arm length of the ground reaction force about the knee joint centre [15]. This moment arm length may increase due to a varus position of the knees, or a medial shift in the location of the centre of pressure of the ground reaction force. Increased medial support in shoes can potentially move the line of action of the ground reaction force medially, thereby increasing the moment arm at the knee [16]. This is in contrast to the alternative method often prescribed to reduce knee external adductor moments, and subsequent loading of the medial knee, which involves wedging the lateral sole [17]. It is therefore important to assess whether medial support has any negative influence on the knee external adductor moment for the population of mature female runners.

The first aim of this study was to test the conclusions of the previous study comparing running gait in mature and young females [4] by repeating this comparison but with a consistent neutral trainer. The second aim was to investigate the influence of a motion control shoe on lower limb biomechanics of both study groups. It was hypothesised that (a) a neutral shoe would result in higher peak rearfoot eversion, knee internal rotation angle and knee external adductor moment for mature compared to younger females; (b) the motion control shoe would yield reduced magnitudes of rearfoot eversion and knee internal rotation in both groups compared to a neutral shoe and (c) the motion control shoe would increase knee external adductor moment.