Department of Defense Biotechnology High Performance Computing Software Applications Institute, Telemedicine and Advanced Technology Research Center, United States Army Medical Research and Development Command, FCMR-TT, 504 Scott Street, Fort Detrick, MD, 21702-5012, USA.
The Henry M. Jackson Foundation for the Advancement of Military Medicine, Inc, Bethesda, MD, 20817, USA.
BMC Musculoskelet Disord. 2023 Jul 24;24(1):604. doi: 10.1186/s12891-023-06733-y.
Tibial stress fracture is a debilitating musculoskeletal injury that diminishes the physical performance of individuals who engage in high-volume running, including Service members during basic combat training (BCT) and recreational athletes. While several studies have shown that reducing stride length decreases musculoskeletal loads and the potential risk of tibial injury, we do not know whether stride-length reduction affects individuals of varying stature differently.
We investigated the effects of reducing the running stride length on the biomechanics of the lower extremity of young, healthy women of different statures. Using individualized musculoskeletal and finite-element models of women of short (N = 6), medium (N = 7), and tall (N = 7) statures, we computed the joint kinematics and kinetics at the lower extremity and tibial strain for each participant as they ran on a treadmill at 3.0 m/s with their preferred stride length and with a stride length reduced by 10%. Using a probabilistic model, we estimated the stress-fracture risk for running regimens representative of U.S. Army Soldiers during BCT and recreational athletes training for a marathon.
When study participants reduced their stride length by 10%, the joint kinetics, kinematics, tibial strain, and stress-fracture risk were not significantly different among the three stature groups. Compared to the preferred stride length, a 10% reduction in stride length significantly decreased peak hip (p = 0.002) and knee (p < 0.001) flexion angles during the stance phase. In addition, it significantly decreased the peak hip adduction (p = 0.013), hip internal rotation (p = 0.004), knee extension (p = 0.012), and ankle plantar flexion (p = 0.026) moments, as well as the hip, knee, and ankle joint reaction forces (p < 0.001) and tibial strain (p < 0.001). Finally, for the simulated regimens, reducing the stride length decreased the relative risk of stress fracture by as much as 96%.
Our results show that reducing stride length by 10% decreases musculoskeletal loads, tibial strain, and stress-fracture risk, regardless of stature. We also observed large between-subject variability, which supports the development of individualized training strategies to decrease the incidence of stress fracture.
胫骨应力性骨折是一种使人虚弱的肌肉骨骼损伤，会降低从事高负荷跑步的个体的身体表现，包括基本战斗训练（BCT）期间的军人和娱乐运动员。虽然有几项研究表明，缩短步幅可以降低肌肉骨骼负荷和胫骨受伤的潜在风险，但我们不知道步幅缩短是否会对不同身高的个体产生不同的影响。
我们研究了降低跑步步幅对不同身高年轻健康女性下肢生物力学的影响。使用短（N=6）、中（N=7）和高（N=7）身材女性的个体化肌肉骨骼和有限元模型，我们计算了每位参与者在跑步机上以 3.0 m/s 的速度以他们的首选步幅和减少 10%的步幅跑步时的下肢关节运动学和动力学以及胫骨应变。使用概率模型，我们估计了 BCT 期间代表美国陆军士兵和马拉松训练的娱乐运动员的跑步方案的骨折风险。
当研究参与者将步幅缩短 10%时，三个身高组之间的关节动力学、运动学、胫骨应变和骨折风险没有显著差异。与首选步幅相比，步幅缩短 10%显著降低了站立阶段的髋关节（p=0.002）和膝关节（p<0.001）屈曲角度的峰值。此外，它还显著降低了髋关节内收（p=0.013）、髋关节内旋（p=0.004）、膝关节伸展（p=0.012）和踝关节跖屈（p=0.026）的峰值时刻，以及髋关节、膝关节和踝关节的关节反作用力（p<0.001）和胫骨应变（p<0.001）。最后，对于模拟方案，步幅缩短将骨折风险的相对风险降低了多达 96%。
我们的研究结果表明，将步幅缩短 10%可以降低肌肉骨骼负荷、胫骨应变和骨折风险，而与身高无关。我们还观察到较大的个体间变异性，这支持制定个体化训练策略以降低骨折发生率。
