Most Military Runners Report Recent Changes in Running Parameters Before Lower Limb Injury Onset
Authors: Fredette Major Anny , Roy Jean-Sébastien , Esculier Jean-Franç ois , Perreault Kadija 
Published: December 2020

ABSTRACT

Introduction
While running is a popular activity because of the health and fitness benefits it provides, the yearly incidence of running-related injuries (RRI) is high across all populations of runners, including military members. The etiology of RRI is multifactorial, and despite the numerous studies on risk factors for RRI, there is no clear consensus in the literature on the relative contribution of several intrinsic or extrinsic risk factors to the development of RRI. Furthermore, little is known on RRI profile and running parameters among Canadian military members. The objectives of this study were to (1) describe the clinical presentation of lower limb RRI and running profile among military members and (2) explore any association between recent changes in running parameters (volume or intensity) and specific RRI diagnoses.

Materials and Methods
This cross-sectional study was conducted in 107 military members from the Canadian Armed Forces (Valcartier Military Base) who presented with a restriction or interruption of running because of lower limb running-related pain. The following variables were collected during a physiotherapy evaluation: injury location and diagnosis, running kinematics (foot strike pattern and step rate), degree of minimalism of running shoes, running parameters in the last 3 months before consultation (volume, duration, frequency, and intensity), and recent changes in training before pain onset. Descriptive statistical analyses were conducted to describe the clinical presentation and running profile, while chi-square tests and multiple correspondence analysis were used to explore the association between recent changes in running parameters and diagnosis. This study was approved by the institutional ethics committee, and participants signed a detailed consent form.

Results
Among the 107 participants included in the study (mean age: 30.7 ± 8.9 years; 13 females), the most common diagnoses were patellofemoral pain (26.2%), medial tibial stress syndrome (11.2%), plantar fasciopathy (9.3%), and sciatica (9.3%). The average Minimalist Index of running shoes was 27.6 ± 18.5%. Step rate was 161.7 ± 10.3 steps per minute, and 73.3% of the participants used a rearfoot strike pattern. The majority of military runners reported previous RRI, gradual onset of symptoms, and recent changes in their training parameters (75.7%) before injury onset. No association was found between recent changes in running volume ((χ2(4) = 2.849; P = .606)) or intensity ((χ2(4) = 1.381; P = .855)) and diagnosis.

Conclusion
This is the first study to specifically investigate RRI and running profile among Canadian military members. The most common injuries were located at the knee, and the most frequent diagnosis was patellofemoral pain. The majority of military runners reported previous RRI as well as recent changes in their running parameters before injury onset, but unique types of recent changes were not associated with specific diagnoses. This study illustrates the need to further investigate the impact of training loads on the development of RRI.