The Isometric Knee Extension Moment-Angle Relationship: Experimental Data and Predictions Based on Cadaver Data

Abstract

The influence of parameter values (i.e., fiber optimum lengths and moment arms) and simplification of the geometry of a Hill-type muscle model on the prediction of normalized maximal isometric knee extension moment to knee joint angle relationship was studied. For that purpose, the geometry of m. quadriceps femoris was modeled in considerable detail, and all parameter values were determined on one set of cadaver specimens that had been selected for muscular appearance. The predicted relationship was compared to that measured in human subjects over the full range of physiological knee angles, and a good correspondence was found (r = .96). The good correspondence could be attributed to the substitution of realistic parameter values into the model. Incorporating complex muscle geometry into the model resulted in a small additional improvement of the prediction. It was speculated that the variation in results of cadaver measurements among studies reflects true differences caused by individuals' levels of physical activity in the period preceding death.Key Words: m. quadriceps femoris, muscle model, geometry, human cadavers Insight into the factors determining performance of motor tasks will benefit practitioners in athletics and rehabilitation. It is generally recognized that performance depends on properties of the musculoskeletal system and on control, with the effects of control being determined by the stimulation patterns that the nervous system sends to the muscles. In order to gain insight into the importance of system properties and control, it is necessary to systematically manipulate these factors and monitor the effects on performance. Unfortunately, system properties cannot be changed in living subjects for obvious reasons, and subjects are unable to systematically manipulate their control. For that reason, researchers have turned to models of the neuromusculoskeletal system. These models may be constructed such that the input consists of muscle stimulation patterns and the output is the movement and therewith the performance on the task (Levine,

Contribution of mono- and biarticular muscles to extending knee joint moments in runners and cyclists

“…This is similar to the difference reported by Herzog et al (6). As in the RF muscle, the muscle fiber length is 25% of the muscle length (16,24); a 20% shorter optimal muscle length for cyclists implies 80% less sarcomeres in series. This is beyond imagination.…”

Musculo-skeletal modelling of NMES-evoked knee extension in spinal cord injury

“…The present authors therefore prefer the option of forcing all quadriceps to peak at the same angle, rather than an arbitrary grouping of three vastii and allowing only rectus femoris to vary. It should be noted, however, that the method of Meijer et al (1998) was trailed for the present study, and resulted in changes to rectus femoris and vastus tendon lengths of only 3% and 1.5%, respectively. The tendon slack lengths resulting from the current study are shown in Table 1, together with those previously reported by Hoy et al (1990) and Meijer et al (1998).…”

“…The present study and that of Hoy et al (1990) adjusted slack lengths for vastus and rectus femoris in order to have both muscles generating peak torque at the knee angle coincident with that generating maximum torque in vivo. Meijer et al (1998) allowed rectus femoris and vastus to achieve peak torques at different knee angles, thus widening the active torque-angle curve. Forcing three vastii to behave as a single group, and allowing only rectus femoris to vary seems, however, to be an artificial solution.…”

“…vastii muscles have been modelled as a single muscle by the present study, in common with the methods of Hoy et al (1990) and Meijer et al (1998), because of the similarity of anatomical properties within the group. The present study and that of Hoy et al (1990) adjusted slack lengths for vastus and rectus femoris in order to have both muscles generating peak torque at the knee angle coincident with that generating maximum torque in vivo.…”

“…For example, Perumal et al (2002) used a single quadratic equation to characterise the change in quadriceps torque with knee angle. By contrast, Meijer et al (1998) used a quadratic function to characterise the variation in single fibre force with fibre length, a helical model for fibre length as a function of muscle length, another quadratic function to give muscle length changes with joint angle and repeated these equations for each of the four quadricep muscles. The latter method, although more numerically complex, has the potential to provide a greater understanding of the underlying mechanisms determining muscle performance.…”