Footwear and Injury Prevention Study

The proposed study will be a non-blinded prospective randomized cohort design.

Subjects will include adult runners of both genders with no history of injury in the 6 months prior to study enrollment. Eligible participants will have no history of surgery or trauma to the lower extremity that might compromise their walking or running gait, and all subjects must be able to comfortably fit into their selected footwear.

Three different foot posture sub-group classifications will be recruited: neutral, mild to moderate, and excessive. The subjects' foot posture will be classified using the Foot Posture Index (Redmond et al. (2006)(1). Twenty four subjects are estimated to be required within each foot posture sub-group; therefore 72 subjects will be our goal for enrollment. Subjects within each foot posture sub-group will be randomized into one of two separate footwear conditions: both the neutral group and the mild to moderate pronator group will be divided to receive either a neutral cushioned running shoe (a.k.a. 'neutral shoe'), or a shoe with mild stability components for controlling overpronation (a.k.a. 'stability shoe'); participants in the excessive pronator sub-group will be randomized to receive either a 'stability shoe' or a shoe will aggressive motion controlling features (a.k.a. 'motion control shoe').

All subjects will undergo an initial baseline test, including an entrance interview for participant eligibility, training history, running injury history and documentation of lower extremity anthropometry (i.e. arch height, knee alignment, standing rearfoot position). Subjects will be randomized during their baseline test to their shoe condition and receive their shoes, training diary and running programme at that time.

Once all subjects have completed their baseline testing, the official running clinic start date will commence on the following Saturday. A running clinic is established so that all subjects will have a chance to meet together, along with knowledgeable run leaders and a study co-investigator (MR), in order to increase group cohesion and provide an opportunity for data monitoring, programme feedback and subject questions. All subjects will begin the running programme at the official running clinic start date. The programme is designed to prepare individuals for a half-marathon (21 kilometre) running event in 13 weeks. Subjects will run on their own time, as indicating in their running programme, for the rest of the week until meeting again the following Saturday. This schedule will be repeated for the entire 13 week duration of the programme.

Outcome variables of interest in this study include: 1) number of injury events, defined as a missed run workout that is associated with running related pain; 2) McGill Pain Questionnaire score(2) ; and 3) Visual Analog Scale (VAS) items for pain at rest, activities of daily living, during or immediately after running, respectively(3) . Outcome variables will be assessed at baseline, at the 6 week point in the running programme, and at the conclusion to the running programme.

All data will be entered into a spreadsheet and statistical analysis software package JMP Version 4.0.0 (SAS Institute Inc., Cary, NC). In calculating statistical power for subject recruitment, a 20% difference in the VAS pain scores across groups will be considered to be a clinically meaningful difference. Accordingly, assuming a standard deviation of 2.3 in the VAS scores, an alpha of 5% and a beta error-level of 10%, twenty four subjects will be required within each foot posture sub-group; therefore 69 subjects will be our goal for enrollment. Each foot posture sub-group will undergo its own analysis procedure. Levene's test of equality of variance will precede a factorial analysis of variance in determining whether there are significant main effects for time and footwear condition, as well as an interaction effect, for all three dependent (or outcome) variables. Alpha will be set at 0.05 for this study.

1. Redmond AC, Crosbie J, Ouvrier RA. Development and validation of a novel rating system for scoring standing foot posture: The Foot Posture Index. Clin Biomech 2006;21:89-98.
2. Melzack R. The McGill Pain Questionnaire: Major properties and scoring methods. Pain. 1975; 1: 277-299.
3. Wewers M.E. \& Lowe N.K. A critical review of visual analogue scales in the measurement of clinical phenomena. Research in Nursing and Health 1990;13: 227-236.