Lyght Michael, Nockerts Matthew, Kernozek Thomas W, Ragan Robert
La Crosse Institute for Movement Science, Department of Health Professions-Physical Therapy Program, University of Wisconsin-La Crosse, La Crosse, WI.
J Appl Biomech. 2016 Aug;32(4):365-72. doi: 10.1123/jab.2015-0183. Epub 2016 Mar 8.
Achilles tendon (AT) injuries are common in runners. The AT withstands high magnitudes of stress during running which may contribute to injury. Our purpose was to examine the effects of foot strike pattern and step frequency on AT stress and strain during running utilizing muscle forces based on a musculoskeletal model and subject-specific ultrasound-derived AT cross-sectional area. Nineteen female runners performed running trials under 6 conditions, including rearfoot strike and forefoot strike patterns at their preferred cadence, +5%, and -5% preferred cadence. Rearfoot strike patterns had less peak AT stress (P < .001), strain (P < .001), and strain rate (P < .001) compared with the forefoot strike pattern. A reduction in peak AT stress and strain were exhibited with a +5% preferred step frequency relative to the preferred condition using a rearfoot (P < .001) and forefoot (P=.005) strike pattern. Strain rate was not different (P > .05) between step frequencies within each foot strike condition. Our results suggest that a rearfoot pattern may reduce AT stress, strain, and strain rate. Increases in step frequency of 5% above preferred frequency, regardless of foot strike pattern, may also lower peak AT stress and strain.
跟腱损伤在跑步者中很常见。跟腱在跑步过程中承受着高强度的压力，这可能会导致损伤。我们的目的是利用基于肌肉骨骼模型的肌肉力量和受试者特定的超声衍生跟腱横截面积，研究跑步时着地方式和步频对跟腱应力和应变的影响。19名女性跑步者在6种条件下进行跑步试验，包括以她们偏好的节奏、偏好节奏+5%和偏好节奏-5%进行后足着地和前足着地模式。与前足着地模式相比，后足着地模式的跟腱峰值应力（P < .001）、应变（P < .001）和应变率（P < .001）更小。相对于使用后足（P < .001）和前足（P = .005）着地模式的偏好条件，当步频比偏好步频增加5%时，跟腱峰值应力和应变会降低。在每种着地条件下，步频之间的应变率没有差异（P > .05）。我们的结果表明，后足着地模式可能会降低跟腱应力、应变和应变率。无论着地模式如何，步频比偏好频率增加5%也可能会降低跟腱峰值应力和应变。
