Foot strike pattern during running, psychosocial factors and musculoskeletal pain in naval school candidates

Abstract

Introduction: Musculoskeletal disorders (MSDs) represent the second most common cause of disability around the globe. In the military, these disorders are the main cause of hospitalization and outpatient visits. They are more frequent in new recruits and are related to the demands of running. Given the economic and logistical impact of these dysfunctions, military studies are needed. There are few studies about the influence of the foot strike pattern (FSP) and psychosocial factors. Objective: To test the accuracy of self-report in the type of strike pattern; to analyse the association between the foot strike pattern on the ground during running and musculoskeletal pain in the lower limbs; to analyse the association between psychosocial factors and musculoskeletal pain in the lower limbs in midshipmen candidates from the naval academy. Methods: A longitudinal observational study was performed through a self-report questionnaire with sociodemographic, anthropometric information, location, intensity and frequency of pain, and psychosocial factors (stressful life events and common mental disorders). The foot strike pattern was evaluated by high-frequency video of running (240 HZ) using a video analysis program (Kinovea 0.8.15). In the data analysis, the sensitivity, specificity and likelihood ratios and respective confidence intervals (CI) of 95% were calculated for the validity analysis of the FSP self-report. Logistic regression analysis was used to test the association between exposure variables (FSP and psychosocial factors) and outcome variables (MSDs). Odds ratios (OD) and respective confidence intervals (CI) of 95% were presented. Results: The proportion of forefoot and midfoot strike pattern during the barefoot running were 31.9% and 21.1%, respectively. During the shod running the frequency of these patterns decreased to 9.2% and 9.7%, respectively. The self-report compared with the shod and barefoot video analysis showed, respectively, a sensitivity of 68% (95% CI 49-83) and 47% (95% CI 36- 58); and a specificity of 66% (95% CI 57-74) and 67% (95% CI 55-77). The LR+ was 1.99 (95% CI 1.42 to 2.79), increasing the post-test probability by only 15%. The LR- was 0.49 (95% CI 0.29 to 0.83), decreasing the post-test probability similarly by 15%. Logistic regression analysis (appendix, article 2) showed common mental disorders as a risk factor for musculoskeletal pain in lower limbs (OR 2.27 95% CI 1.01 to 5.08). Conclusion: Shod running induced a change from the forefoot or midfoot to a rearfoot strike pattern. The accuracy of the self-report when compared to the video analysis was higher for the shod running. However, self-report was not an accurate tool to substitute the video analysis. Common mental disorders increase the risk of musculoskeletal disorder in the lower limbs in the military during basic training at the naval academy.