Military Performance Division, United States Army Research Institute of Environmental Medicine, Natick, MA 01760, USA; Endocrine Unit, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114 , USA.
Department of Physical Medicine and Rehabilitation, Spaulding Rehabilitation Hospital, Harvard Medical School, Cambridge, MA 02138, USA.
J Sport Health Sci. 2023 May;12(3):406-413. doi: 10.1016/j.jshs.2022.02.004. Epub 2022 Feb 23.
Bone stress injuries (BSIs) are common in female runners, and recurrent BSI rates are high. Previous work suggests an association between higher impact loading during running and tibial BSI. However, it is unknown whether impact loading and fatigue-related loading changes discriminate women with a history of multiple BSIs. This study compared impact variables at the beginning of a treadmill run to exertion and the changes in those variables with exertion among female runners with no history of BSI as well as among those with a history of single or multiple BSIs.
We enrolled 45 female runners (aged 18-40 years) for this cross-sectional study: having no history of diagnosed lower extremity BSI (N-BSI, n = 14); a history of 1 lower extremity BSI (1-BSI, n = 16); and diagnosed by imaging, or a history of multiple (≥3) lower extremity BSIs (M-BSI, n = 15). Participants completed a 5-km race speed run on an instrumented treadmill while wearing an Inertial Measurement Unit. The vertical average loading rate (VALR), vertical instantaneous loading rate (VILR), vertical stiffness during impact via instrumented treadmill, and tibial shock determined as the peak positive tibial acceleration via Inertial Measurement Unit were measured at the beginning and the end of the run.
There were no differences between groups in VALR, VILR, vertical stiffness, or tibial shock in a fresh or exerted condition. However, compared to N-BSI, women with M-BSI had greater increase with exertion in VALR (-1.8% vs. 6.1%, p = 0.01) and VILR (1.5% vs. 4.8%, p = 0.03). Similarly, compared to N-BSI, vertical stiffness increased more with exertion among women with M-BSI (-0.9% vs. 7.3%, p = 0.006) and 1-BSI (-0.9% vs. 1.8%, p = 0.05). Finally, compared to N-BSI, the increase in tibial shock from fresh to exerted condition was greater among women with M-BSI (0.9% vs. 5.5%, p = 0.03) and 1-BSI (0.9% vs. 11.2%, p = 0.02).
Women with 1-BSI or M-BSIs experience greater exertion-related increases in impact loading than women with N-BSI. These observations imply that exertion-related changes in gait biomechanics may contribute to risk of BSI.
骨应力性损伤（BSI）在女性跑者中很常见，且复发性 BSI 发生率较高。既往研究提示，跑步过程中的冲击负荷与胫骨 BSI 之间存在相关性。然而，目前尚不清楚冲击负荷和与疲劳相关的负荷变化是否可以区分出有多次 BSI 病史的女性。本研究比较了无 BSI 病史（无 BSI，N-BSI）、单次 BSI 病史（1-BSI）和多次（≥3 次）BSI 病史（M-BSI）女性跑者在开始跑步机跑步时的冲击变量和随着跑步的进行这些变量的变化。
我们对 45 名女性跑步者（年龄 18-40 岁）进行了这项横断面研究：无下肢 BSI 病史（N-BSI，n=14）；下肢 BSI 病史 1 次（1-BSI，n=16）；通过影像学诊断或有下肢 BSI 病史≥3 次（M-BSI，n=15）。参与者在配备惯性测量单元的跑步机上完成 5km 比赛速度跑。在跑步开始和结束时，通过惯性测量单元测量垂直平均加载率（VALR）、垂直瞬时加载率（VILR）、仪器化跑步机上冲击时的垂直刚度以及胫骨冲击，即惯性测量单元测量的胫骨正向加速度峰值。
在新鲜或疲劳状态下，VALR、VILR、垂直刚度或胫骨冲击在各组之间无差异。然而，与 N-BSI 相比，M-BSI 女性在 VALR（-1.8% vs. 6.1%，p=0.01）和 VILR（1.5% vs. 4.8%，p=0.03）方面的负荷增加随运动而增加的幅度更大。同样，与 N-BSI 相比，M-BSI（-0.9% vs. 7.3%，p=0.006）和 1-BSI（-0.9% vs. 1.8%，p=0.05）女性的垂直刚度在运动中增加得更多。最后，与 N-BSI 相比，M-BSI（0.9% vs. 5.5%，p=0.03）和 1-BSI（0.9% vs. 11.2%，p=0.02）女性从新鲜状态到疲劳状态胫骨冲击的增加幅度更大。
1-BSI 或 M-BSI 女性在运动相关的冲击负荷增加方面的表现，要比 N-BSI 女性更为明显。这些观察结果表明，步态生物力学中与疲劳相关的变化可能是 BSI 风险的一个因素。
