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您的检索式：作者名="Timothy R.Derrick"
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| 1 | 前脚掌着地和后脚跟着地跑步中的冲击震动频率成分及衰减(英文)显示文摘背景:研究显示,与脚后跟着地跑步模式相比,前脚掌着地跑步模式可通过降低冲击相关参数来降低引发跑步相关的过劳性损伤的风险。但现有研究仅比较了不同着地模式冲击参数的时域部分。由于冲击震动的频率成分和衰减度可能对损伤风险及预防非常重要,因此本研究旨在探究后脚跟着地和前脚掌着地跑步者的头部和胫骨加速信号功率以及冲击衰减方面的差别。方法:选取惯用后脚跟和前脚掌着地的跑步者各19名,让其按照各自习惯使用的着地模式,以3.5m/s的速度在跑步机上跑步,收集其胫骨和头部加速数据,计算第1和第2个头部加速峰值的量级和胫骨正向加速度峰值。计算各个信号的功率谱密度来转换头部加速度的频域部分,用相当于胫骨的头部信号的转换函数计算冲击衰减。结果:后脚跟着地时胫骨的正向加速度峰值和信号功率在较低和较高的范围内明显大于前脚掌着地(p<0.05)。第1和第2个头部加速度峰值和头部信号功率在两种跑步模式下均无明显差异(p>0.05)。后脚跟着地跑步模式下,由于胫骨加速度增大,冲击衰减度在较低和较高的范围内均会增大(p<0.05)。结论:不同跑步模式冲击震动频率成分不同,说明衰减的主要机制有差异。虽然冲击衰减机制和运动损伤间的关系尚不清晰,但因冲击成分不同,也许两种跑步模式都无法有效避免损伤,不同模式中的持续损伤类型各不相同。 | Allison H.Gruber Katherine A.Boyer Timothy R.Derrick Joseph Hamill | 2014 | Journal of Sport and Health Science2014，3，2： | 2 |
| 2 | Speed and surface steepness affect internal tibial loading during running显示文摘Background:Internal tibial loading is influenced by modifiable factors with implications for the risk of stress injury.Runners encounter varied surface steepness(gradients)when running outdoors and may adapt their speed according to the gradient.This study aimed to quantify tibial bending moments and stress at the anterior and posterior peripheries when running at different speeds on surfaces of different gradients.Methods:Twenty recreational runners ran on a treadmill at 3 different speeds(2.5 m/s,3.0 m/s,and 3.5 m/s)and gradients(level:0%;uphill:+5%,+10%,and+15%;downhill:-5%,-10%,and-15%).Force and marker data were collected synchronously throughout.Bending moments were estimated at the distal third centroid of the tibia about the medial-lateral axis by ensuring static equilibrium at each 1%of stance.Stress was derived from bending moments at the anterior and posterior peripheries by modeling the tibia as a hollow ellipse.Two-way repeated-measures analysis of variance were conducted using both functional and discrete statistical analyses.Results:There were significant main effects for running speed and gradient on peak bending moments and peak anterior and posterior stress.Higher running speeds resulted in greater tibial loading.Running uphill at+10%and+15%resulted in greater tibial loading than level running.Running downhill at-10%and-15%resulted in reduced tibial loading compared to level running.There was no difference between+5%or-5%and level running.Conclusion:Running at faster speeds and uphill on gradients≥+10%increased internal tibial loading,whereas slower running and downhill running on gradients≥-10%reduced internal loading.Adapting running speed according to the gradient could be a protective mechanism,providing runners with a strategy to minimize the risk of tibial stress injuries. | Hannah Rice Markus Kurz Patrick Mai Leon Robertz Kevin Bill Timothy R.Derrick Steffen Willwacher | 2024 | Journal of Sport and Health Science2024，13，1： | 1 |
| 3 | Finite Element Analysis of Femoral Strains in Older Adults During Stair Ascent and Descent显示文摘Purpose Understanding the femur load environment during daily activity is necessary for the understanding of risk of femoral pain,pain related falls,and femoral fractures,which could help the design of osteogenic exercises or the preventa-tive methods for older adults.Methods Using the finite element femur analysis,this study was to estimate the femoral strains at 9 cross-sections along the long axis of femur for stair ascent and descent(n=17;age:50-65 years).Motion analysis and inverse dynamics were com-bined with musculoskeletal modelling and optimization,then were used as input to a 3-D femur model to estimate femoral strains.Strains at the hip contact force peaks were calculated.Results The compressive and tensile strains during stair descent were greater than ascent for all or most cross-sections,especially for the proximal cross-sections of the femur:stair ascent produced−324.0±103.8 to−483.7±191.0μεcompressive strains and descent produced−608.8±288.4 to 1016.0±444.1με;stair ascent produced 336.2±105.4 to 391.8±136.9μεtensile strains and descent produced 546.9±252.8 to 741.7±333.6με.Conclusion Strains represent the material deformation effect on the bone due to the sum of all the bone external loads.Using bone strains could help future studies analyze load conditions in a more comprehensive way for other physical activities,which predicts the risk of stress fractures and tests if alternative methods(gait type change)could reduce stress and strain effectively. | Chen Deng Jason C.Gillette Timothy R.Derrick | 2022 | Journal of Science in Sport and Exercise2022，4，2： | 0 |
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