PUMA publications for /group/simtech/EstimationTue Jul 19 11:10:29 CEST 2022Frontiers in Physiology05Exhaustion of Skeletal Muscle Fibers Within Seconds: Incorporating Phosphate Kinetics Into a Hill-Type Model112020biomechanics analysis endurance estimation fatigue optimization dynamics parameter sensitivity time first-order Tue Jul 19 11:10:29 CEST 2022Scientific Reports11119559Considerations on the human Achilles tendon moment arm for in vivo triceps surae muscle--tendon unit force estimates102020joint maximum range estimation the corresponding muscle of Far angle working force TS on 11Moment arm-angle functions (MA-a-functions) are commonly used to estimate in vivo muscle forces in humans. However, different MA-a-functions might not only influence the magnitude of the estimated muscle forces but also change the shape of the muscle's estimated force-angle relationship (F-a-r). Therefore, we investigated the influence of different literature based Achilles tendon MA-a-functions on the triceps surae muscle--tendon unit F-a-r. The individual in vivo triceps torque--angle relationship was determined in 14 participants performing maximum voluntary fixed-end plantarflexion contractions from 18.3{\textdegree}{\thinspace}{\textpm}{\thinspace}3.2{\textdegree} plantarflexion to 24.2{\textdegree}{\thinspace}{\textpm}{\thinspace}5.1{\textdegree} dorsiflexion on a dynamometer. The resulting F-a-r were calculated using 15 literature-based in vivo Achilles tendon MA-a-functions. MA-a-functions affected the F-a-r shape and magnitude of estimated peak active triceps muscle--tendon unit force. Depending on the MA-a-function used, the triceps was solely operating on the ascending limb (n{\thinspace}={\thinspace}2), on the ascending limb and plateau region (n{\thinspace}={\thinspace}12), or on the ascending limb, plateau region and descending limb of the F-a-r (n{\thinspace}={\thinspace}1). According to our findings, the estimated triceps muscle--tendon unit forces and the shape of the F-a-r are highly dependent on the MA-a-function used. As these functions are affected by many variables, we recommend using individual Achilles tendon MA-a-functions, ideally accounting for contraction intensity-related changes in moment arm magnitude.Tue Dec 07 20:40:52 CET 2021Kyoto, Japan17th International Symposium on Mathematical Theory of Networks and Systems{R}obust estimation with dynamic integral quadratic constraints2006peerReviewed Estimation iqc imng