Effects of peak ankle dorsiflexion angle on lower extremity biomechanics and pelvic motion during walking and jogging

In this study the variation in ground reaction force parameters was investigated with respect to adaptations to speed and mode of progression, and to type of foot-strike. Twelve healthy male subjects were studied during walking (1.0-3.0 m s-1) and running (1.5-6.0 m s-1). The subjects were selected with respect to foot-strike pattern during running. Six subjects were classified as rearfoot strikers and six as forefoot strikers. Constant speeds were accomplished by pacer lights beside an indoor straightway and controlled by means of a photo-electronic device. The vertical, anteroposterior and mediolateral force components were recorded with a force platform. Computer software was used to calculate durations, amplitudes and impulses of the reaction forces. The amplitudes were normalized with respect to body weight (b.w.). Increased speed was accompanied by shorter force periods and larger peak forces. The peak amplitude of the vertical reaction force in walking and running increased with speed from approximately 1.0 to 1.5 b.w. and 2.0 to 2.9 b.w. respectively. The anteroposterior peak force and mediolateral peak-to-peak force increased about 2 times with speed in walking and about 2-4 times in running (the absolute values were on average about 10 times smaller than the vertical). The transition from walking to running resulted in a shorter support phase duration and a change in the shape of the vertical reaction force curve. The vertical peak force increased whereas the vertical impulse and the anteroposterior impulses and peak forces decreased. In running the vertical force showed an impact peak at touch-down among the rearfoot strikers but generally not among the forefoot strikers. The first mediolateral force peak was laterally directed (as in walking) for the rearfoot strikers but medially for the forefoot strikers. Thus, there is a change with speed in the complex interaction between vertical and horizontal forces needed for propulsion and equilibrium during human locomotion. The differences present between walking and running are consequences of fundamental differences in motor strategies between the two major forms of human progression.

Plantar fasciitis is one of the more common soft-tissue disorders of the foot, yet little is known about its etiology. The purpose of the present study was to use an epidemiological design to determine whether risk factors for plantar fasciitis could be identified. Specifically, we examined the risk factors of limited ankle dorsiflexion with the knee extended, obesity, and time spent weight-bearing. We used a matched case-control design, with two controls for each patient. The matching criteria were age and gender. We identified fifty consecutive patients with unilateral plantar fasciitis who met the inclusion criteria. The data that were collected included height, weight, whether the subject spent the majority of the workday weight-bearing, and whether the subject was a jogger or runner. We used a reliable goniometric method to measure passive ankle dorsiflexion bilaterally. The main outcome measure was the adjusted odds ratio of plantar fasciitis associated with varying degrees of limitation of ankle dorsiflexion, different levels of body mass, and the subjects' reports on weight-bearing. Individuals with 10 degrees of ankle dorsiflexion. Individuals who had a body-mass index of >30 kg/m (2) had an odds ratio of 5.6 (95% confidence interval, 1.9 to 16.6) when compared with the referent group of individuals who had a body-mass index of 30 kg/m (2) are also at increased risk for the development of plantar fasciitis. Reduced ankle dorsiflexion, obesity, and work-related weight-bearing appear to be independent risk factors for plantar fasciitis. Reduced ankle dorsiflexion appears to be the most important risk factor.