Roberts Thomas J, Belliveau Richard A
Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA.
J Exp Biol. 2005 May;208(Pt 10):1963-70. doi: 10.1242/jeb.01555.
During uphill running limb muscles must perform net mechanical work to increase the body's potential energy, while during level running the net mechanical work required is negligible as long as speed is constant. The increased demands for work as running incline increases might be met by an increase in power output at all joints, or only a subset of joints. We used inverse dynamics to determine which joints modulate net work output in humans running uphill. We measured joint kinematics and ground reaction force during moderate speed running at 0 degrees , 6 degrees and 12 degrees inclines. Muscle force, joint power and work per step were determined at the ankle, knee and hip using inverse dynamics calculations. We found that virtually all of the increase in work output with increasing incline resulted from increases in net work done at the hip (-0.25+/-0.23 J kg(-1), level, vs 0.88+/-0.10 J kg(-1), 12 degrees incline), while the knee and ankle performed similar functions at all inclines. The increase in work output at the hip resulted primarily from a large increase in average net muscle moment during stance (2.07+/-17.84 Nm, level, vs 87.30+/-13.89 Nm, 12 degrees incline); joint excursion increased by only 20% (41.22+/-3.41 degrees , level, vs 49.22+/-2.35 degrees , 12 degrees incline). The increase in hip muscle moment and power was associated with a poorer mechanical advantage for producing force against the ground. The increase in hip moment with running incline allows for the production of the power necessary to lift the body. This power may be developed by hip extensors or by transfer of power from muscles at other joints via biarticular muscles.
在上坡跑时，肢体肌肉必须进行净机械功以增加身体的势能，而在平地上跑时，只要速度恒定，所需的净机械功就可以忽略不计。随着跑步坡度增加对功的需求增加，可能通过所有关节功率输出的增加来满足，或者仅通过一部分关节来满足。我们使用逆动力学来确定在上坡跑的人类中哪些关节调节净功输出。我们在0度、6度和12度坡度的中等速度跑步过程中测量了关节运动学和地面反作用力。使用逆动力学计算确定了踝关节、膝关节和髋关节处的肌肉力、关节功率和每步的功。我们发现，随着坡度增加，几乎所有功输出的增加都源于髋关节处净功的增加（水平时为-0.25±0.23 J·kg⁻¹，12度坡度时为0.88±0.10 J·kg⁻¹），而膝关节和踝关节在所有坡度下执行类似功能。髋关节处功输出的增加主要源于支撑期平均净肌肉力矩的大幅增加（水平时为2.07±17.84 N·m，12度坡度时为87.30±13.89 N·m）；关节活动范围仅增加了20%（水平时为41.22±3.41度，12度坡度时为49.22±2.35度）。髋关节肌肉力矩和功率的增加与产生地面反作用力的机械优势较差有关。随着跑步坡度增加髋关节力矩的增加使得能够产生提升身体所需的功率。这种功率可能由髋关节伸肌产生，或者通过双关节肌肉从其他关节的肌肉传递功率来产生。
