Kautz S A, Hull M L, Neptune R R
Biomedical Engineering Graduate Group, University of California, Davis.
J Biomech. 1994 Dec;27(12):1459-67. doi: 10.1016/0021-9290(94)90195-3.
The hypothesis that the sum of the absolute changes in mechanical energy (internal work) is correlated with the muscular mechanical energy expenditure (MMEE) was tested using two elliptical chainrings, one that reduced and one that increased the internal work (compared to circular). Upper and lower bounds were put on the extra MMEE (work done by net joint torques in excess of the external work) with respect to the effect of intercompensation between joint torques due to biarticular muscles. This was done by having two measures of MMEE, one that allowed no intercompensation and one that allowed complete intercompensation between joints spanned by biarticular muscles. Energy analysis showed no correlation between internal work and the two measures of MMEE. When compared to circular, the chainring that reduced internal work increased MMEE, and phases of increased crank velocity associated with the elliptical shape resulted in increased power absorbed by the upstroke leg as it was accelerated against gravity. The resulting negative work necessitated additional positive work. Thus, the hypothesis that the internal work is correlated with MMEE was found to be invalid, and the total mechanical work done cannot be estimated by summing the internal and external work. Changes in the dynamics of cycling caused by a non-circular chainring may affect performance and must be considered during the non-circular chainring design process.
使用两个椭圆形链轮对机械能（内功）绝对变化之和与肌肉机械能消耗（MMEE）相关的假设进行了测试，其中一个椭圆形链轮会减少内功，另一个则会增加内功（与圆形链轮相比）。针对双关节肌肉引起的关节扭矩之间的相互补偿效应，确定了额外MMEE（净关节扭矩所做的功超过外部功）的上限和下限。这是通过对MMEE进行两种测量来实现的，一种测量不允许相互补偿，另一种测量允许双关节肌肉跨越的关节之间完全相互补偿。能量分析表明，内功与MMEE的两种测量之间没有相关性。与圆形链轮相比，减少内功的链轮会增加MMEE，并且与椭圆形形状相关的曲柄速度增加阶段会导致上冲程腿部在克服重力加速时吸收的功率增加。由此产生的负功需要额外的正功。因此，发现内功与MMEE相关的假设是无效的，并且不能通过将内功和外功相加来估计所做的总机械功。非圆形链轮引起的骑行动力学变化可能会影响性能，并且在非圆形链轮设计过程中必须予以考虑。
