The relationship between two different mechanical cost functions and muscle oxygen consumption

Praagman, M.; Chadwick, Edward K.; Helm, F.C.T. van der; Veeger, H.E.J.

doi:10.1016/j.jbiomech.2004.11.034

Cited by 117 publications

(120 citation statements)

References 22 publications

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“…Since the model includes more muscles than degrees of freedom, a nonlinear constrained optimization routine is used to resolve these torques into individual muscle forces. The optimization aims to minimize muscle energy consumption, using a cost function proposed by Praagman et al [20]. This method showed good correspondence with experimental muscle activity approximated using surface EMG.…”

Section: Simulationsmentioning

confidence: 99%

Selection of muscle and nerve-cuff electrodes for neuroprostheses using customizable musculoskeletal model

Blana¹,

Hincapie²,

Chadwick³

et al. 2013

JRRD

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Abstract-Neuroprosthetic systems based on functional electrical stimulation aim to restore motor function to individuals with paralysis following spinal cord injury. Identifying the optimal electrode set for the neuroprosthesis is complicated because it depends on the characteristics of the individual (such as injury level), the force capacities of the muscles, the movements the system aims to restore, and the hardware limitations (number and type of electrodes available). An electrode-selection method has been developed that uses a customized musculoskeletal model. Candidate electrode sets are created based on desired functional outcomes and the hardware limitations of the proposed system. Inverse-dynamic simulations are performed to determine the proportion of target movements that can be accomplished with each set; the set that allows the most movements to be performed is chosen as the optimal set. The technique is demonstrated here for a system recently developed by our research group to restore whole-arm movement to individuals with high-level tetraplegia. The optimal set included selective nerve-cuff electrodes for the radial and musculocutaneous nerves; single-channel cuffs for the axillary, suprascapular, upper subscapular, and long-thoracic nerves; and muscle-based electrodes for the remaining channels. The importance of functional goals, hardware limitations, muscle and nerve anatomy, and surgical feasibility are highlighted.

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Section: Simulationsmentioning

confidence: 99%

Selection of muscle and nerve-cuff electrodes for neuroprostheses using customizable musculoskeletal model

Blana¹,

Hincapie²,

Chadwick³

et al. 2013

JRRD

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show abstract

“…By means of inverse dynamic simulation, muscle forces required to satisfy both the mechanical force equilibrium and moment equilibrium were calculated. Two different load sharing criteria were applied: a stress cost function, i.e., minimization of summed squared muscle stresses, and a compound linear and quadratic energy cost function [19]. Based on the estimated muscle forces, the Principal Actions for the muscles in the DSEM were calculated (PA sim ) [3,4].…”

Section: Model Simulationsmentioning

confidence: 99%

“…Praagman et al [19] introduced a combination of a linear stress and a quadratic energy cost function, which turned out to fit best with non-linear in vivo obtained muscle energy expenditure around the elbow using near infrared spectroscopy. They stated that most cost functions are chosen rather arbitrary, mainly due to the fact that validation is difficult since muscle force cannot be measured accurately in vivo.…”

Section: Introductionmentioning

confidence: 99%

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Arm load magnitude affects selective shoulder muscle activation

Steenbrink

Meskers

Vliet

et al. 2009

Med Biol Eng Comput

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For isometric tasks, shoulder muscle forces are assumed to scale linearly with the external arm load magnitude, i.e., muscle force ratios are constant. Inverse dynamic modeling generally predicts such linear scaling behavior, with a critical role for the arbitrary load sharing criteria, i.e., the ''cost function''. We tested the linearity of the relation between external load magnitude exerted on the humerus and shoulder muscle activation. Six isometric force levels ranging from 17 to 100% of maximal arm force were exerted in 24 directions in a plane perpendicular to the longitudinal axis of the humerus. The direction of maximum muscle activation, the experimentally observed so called Principal Action (PA), was determined for each force magnitude in 12 healthy subjects. This experiment was also simulated with the Delft Shoulder and Elbow Model (DSEM) using two cost functions: (1) minimizing muscle stress and (2) a compound, energy related cost function. PA, both experimental (PA exp ) and simulated (PA sim ), was expected not to change with arm forces magnitudes. PA exp of the mm. trapezius pars descendens, deltoideus pars medialis and teres major changed substantially as a function of external force magnitude, indicating external load dependency of shoulder muscle activation. In DSEM simulations, using the stress cost function, small non-linearities in the muscle forceexternal load dependency were observed, originating from gravitational forces working on clavicular and scapular bone masses. More pronounced non-linearities were introduced by using the compound energy related cost function, but no similarity was observed between PA exp and PA sim .

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“…Although the general opinion was that musculoskeletal modeling has taken a great flight and has been and will be of great importance for understanding and quantifying musculoskeletal function, it was also clear that two major issues prevent widespread clinical use. Firstly, the general models available now need to be more thoroughly validated and tested: results by Steenbrink et al [16] indicated that there is no perfect simulation-experiment match as yet, although new cost functions [15] appear to improve results. Secondly, and also influencing the validation issue, it is quite likely that for clinical purposes models need to be individualized.…”

Section: Introductionmentioning

confidence: 99%

Shoulder biomechanics: today’s consensus and tomorrow’s perspectives

Cutti

Veeger

2009

Med Biol Eng Comput

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Shoulder biomechanics is a fast growing field, which is progressively expanding its focus to include more applied research. The papers included in this Special Issue confirm this trend. After a classification of the papers as dealing with fundamental or applied research through theoretical or experimental methods, in this Editorial we tried to summarize the elements of consensus and the open issues discussed during the last International Shoulder Group meeting, held in Bologna (Italy) in 2008.

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The relationship between two different mechanical cost functions and muscle oxygen consumption

Cited by 117 publications

References 22 publications

Selection of muscle and nerve-cuff electrodes for neuroprostheses using customizable musculoskeletal model

Selection of muscle and nerve-cuff electrodes for neuroprostheses using customizable musculoskeletal model

Arm load magnitude affects selective shoulder muscle activation

Shoulder biomechanics: today’s consensus and tomorrow’s perspectives

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