Neuromuscular Research Laboratory, Department of Sports Medicine and Nutrition, University of Pittsburgh, Pittsburgh, PA, USA.
Neuromuscular Research Laboratory, Department of Sports Medicine and Nutrition, University of Pittsburgh, Pittsburgh, PA, USA.
Gait Posture. 2021 Jul;88:22-27. doi: 10.1016/j.gaitpost.2021.04.040. Epub 2021 Apr 27.
Military personnel in combat roles often perform gait tasks with additional load, which can affect the contributions of joint mechanical work (positive and negative). Furthermore, different locomotion patterns can also affect joint specific work contributions. While mean behavior of joint work is important to understanding gait, changes in joint kinetic modulation, or the regulation/control of stride-to-stride joint work variability is necessary to elucidate locomotor system function. Suboptimal modulation exhibited as a stochastic time-series (large fluctuation followed by an opposite smaller fluctuation) could potentially affect locomotion efficiency and portend injury risk. It remains unclear how the locomotor system responds to a combination of load perturbations and varying locomotion patterns.
What are the interactive effects of load magnitude and locomotion pattern on joint positive/negative work and joint work modulation in healthy, active, recruit-aged women?
Eleven healthy, active, recruit-aged (18-33 years) women ran and forced-marched (walking at a velocity an individual would typically jog) in bodyweight (BW), an additional 25 % of BW (+25 %BW) and an additional 45 % of BW (+45 %BW) conditions at a velocity above their gait transition velocity. Joint work was calculated as the time integral of joint power. Joint work modulation was assessed with detrended fluctuation analysis (DFA) on consecutive joint work time-series.
Joint work contributions shifted proximally for forced-marching demonstrated by lesser (p < .001) positive/negative ankle work but greater (p = .001) positive hip work contributions compared to running. Running exhibited optimal positive ankle work modulation compared to forced-marching (p = .040). Knee and ankle negative joint work modulation was adversely impacted compared to the hip during forced-marching (p < .001).
Employing forced-marching gait while under loads of 25 and 45 % of BW reduces the ability of the plantar-flexors and knee extensors to optimally contribute to energy absorption and propulsion in recruit-aged women, potentially reducing metabolic efficiency and increasing injury risk.
在战斗角色中，军事人员经常在额外负荷下执行步态任务，这可能会影响关节机械功（正功和负功）的贡献。此外，不同的运动模式也会影响关节特定工作的贡献。虽然关节工作的平均行为对于理解步态很重要，但关节动力学调制的变化，或者说步幅间关节工作变异性的调节/控制，对于阐明运动系统功能是必要的。表现为随机时间序列的次优调制（大波动后跟随小相反波动）可能会影响运动效率并预示受伤风险。目前尚不清楚运动系统如何应对负荷扰动和不同运动模式的组合。
在健康、活跃、新兵年龄段的女性中，负荷大小和运动模式对关节正/负功和关节工作调制的交互影响是什么？
11 名健康、活跃、新兵年龄段（18-33 岁）的女性以高于步态过渡速度的速度跑步和强制行军（以个人通常慢跑的速度行走），分别处于体重（BW）、25%体重附加（+25%BW）和 45%体重附加（+45%BW）条件下。关节功被计算为关节功率的时间积分。关节工作调制通过连续关节工作时间序列的去趋势波动分析（DFA）进行评估。
与跑步相比，强制行军的表现为踝关节的正/负功贡献向近端转移，导致正/负功（p < .001）减少，但髋关节的正功贡献更大（p = .001）。与强制行军相比，跑步时踝关节的正功调制表现出最佳状态（p = .040）。与髋关节相比，在强制行军时，膝关节和踝关节的负关节工作调制受到不利影响（p < .001）。
在 25%和 45%体重负荷下采用强制行军步态会降低新兵年龄段女性跖屈肌和伸膝肌对能量吸收和推进的最佳贡献能力，这可能会降低代谢效率并增加受伤风险。
