Incidence of injuries and associated factors in treadmill runners: a prospective cohort study

Abstract Aims: To determine the incidence of injuries in exclusive treadmill runners and the main associated factors in 24 weeks. Methods: The incidence of injuries was investigated every two weeks by an electronic form. To analyze the associated factors, muscle force output, range of motion, and flexibility were investigated. To perform a descriptive analysis (baseline) and injury predictive factors (regression), we divided runners into two groups, injured and uninjured. Comparisons between groups were assessed evaluated by Student's t-test, Mann-Whitney, or Chi-square test. The relationship between associated factors and incidence of injuries was estimated by Logistic regression analysis. The model's accuracy was assessed by the receiver-operating characteristic curve (ROC). Thirty-seven runners completed the study. Results: The incidence of injuries was 6.8 per 1,000 hours of exposure. Among the associated factors, we highlight that runners with higher hip flexor force output were 4 times more likely not to injure (OR 4.0; CI 95% 1.03 -16.23) and lower knee extensor force output was related to a greater chance of injury (OR .24; 95% CI .65 - .93). The area under the ROC curve was 0.84. Conclusion: The incidence of injuries in treadmill runners was high. The factors associated with the injuries were the output of the flexor strength of the hip and the extensor force of the knee.

摘要
研究目的：旨在明确24周内纯跑步机跑者的运动损伤发生率及其主要相关影响因素。
研究方法：本研究通过电子问卷每两周对损伤发生率进行调研。为分析相关影响因素，本研究对受试者的肌肉力量输出、关节活动度及柔韧性进行了检测。为开展描述性分析（基线数据）及损伤预测因子（回归分析）研究，本研究将跑者分为损伤组与未损伤组两组。组间比较采用学生t检验（Student's t-test）、曼-惠特尼检验（Mann-Whitney test）或卡方检验（Chi-square test）进行评估。相关影响因素与损伤发生率之间的关联通过逻辑回归（Logistic regression）分析进行量化评估。模型的预测准确性通过受试者工作特征曲线（Receiver-operating characteristic curve, ROC）进行评价。最终共有37名跑者完成本研究。
研究结果：研究期间损伤发生率为每1000小时训练暴露量6.8例。在相关影响因素中，值得注意的是，髋屈肌力量输出较高的跑者未发生损伤的概率是其他跑者的4倍（优势比（Odds Ratio, OR）=4.0；95%置信区间（Confidence Interval, CI）：1.03~16.23）；而膝伸肌力量输出较低的跑者发生损伤的风险更高（优势比（Odds Ratio, OR）=0.24；95%置信区间（Confidence Interval, CI）：0.65~0.93）。受试者工作特征曲线下面积为0.84。
结论：纯跑步机跑者的运动损伤发生率较高。与损伤发生相关的影响因素为髋屈肌力量输出与膝伸肌力量输出。