Walter Herzog’s research while affiliated with University of Calgary and other places

... Frozen biopsies were transferred to a rigor/glycerol (50/50, v/v) solution for 18 h at − 20 • C and then skinned in a relaxing solution containing 1 % triton X-100 for 3 h on ice (Feng and Jin, 2020;Ma et al., 2022). This freezing and then skinning technique has been shown to preserve the active and passive properties of single muscle fibres (Joumaa et al., 2025). A single fibre was dissected and glued between a length controller and a force transducer (322C and 403A, respectively, Aurora Scientific Inc, Ontario, Canada). ...

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Maximal active force in skinned muscle fibres from children with cerebral palsy

... Participants performed a standardized warmup protocol 27,28 including self-selected lower-body static and dynamic stretching, 10 minutes of moderate-intensity cycling on an ergometer, and 4 bouts of maximal intensity cycling intervals utilizing a 10:50 seconds workto-rest ratio. Next, participants performed standardized warm up/ familiarization trials for the loaded CMJ testing protocol (ie, 1-2 practice trials at each load using an identical cueing protocol as described in the CMJ velocity-load testing subsection) and on a robotic servomotor isokinetic leg press (ie, 5 concentric and eccentric leg press actions completed at progressively increasing rates of perceived effort; Fv Seger, Treadmetrix). ...

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Predicting Multijoint Maximal Eccentric and Concentric Strength With Force-Velocity Jump Mechanics in Collegiate Athletes

... With the relation between kinetics and moment arm elucidated, it is clear how crucial moment arm is to biomechanical analysis. For example, for accurate musculoskeletal simulation, there has been a major focus on contraction dynamics, such as improving muscle models [21,22], investigating the sensitivity of muscle force estimation to musculotendon parameters [23][24][25], and performing large-scale human measurements for model calibration [26,27]. Nevertheless, these efforts contribute solely to the accuracy of F in Eq. (1), while r r r is equally crucial in predicting moment output or estimating muscle activation. ...

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Muscle Moment Arm-Joint Angle Relations in the Hip, Knee, and Ankle: A Visualization of Datasets

... The cytoskeleton resists deformation but can adapt to loading as per the tensegrity model (discussed in [215,216]). Deformation of cells in response to loading (discussed in [217,218]) leads to changes in gene expression and thus, the integrity of such a system is central to growth and maturation of these tissues. Similarly, loss of such mechanical stimulation is not a null event, as the cells in a tissue respond to such conditions by derepressing expression of a catabolic cascade of genes leading to tissue atrophy [219]. ...

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Regulation of Joint Tissues and Joint Function: Is There Potential for Lessons to Be Learned Regarding Regulatory Control from Joint Hypermobility Syndromes?

... For eccentric and concentric MVCs, a sled velocity of 0.2 m/s was selected based on previously reported average velocities obtained during 1 RM squat testing. 29 Finally, according to a previously established methodology, 30 participants performed CMJ velocity-load testing, which included unloaded CMJ testing and CMJ testing with an additional external load of 30% and 60% of the participants body weight. ...

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Predicting Multijoint Maximal Eccentric and Concentric Strength With Force-Velocity Jump Mechanics in Collegiate Athletes

... Knee injuries impose a substantial burden on athletes across all sports, with significantly higher rates observed in female compared to male athletes [1,2]. These injuries impact both immediate athletic performance and long-term joint health, while placing substantial demands on healthcare resources [3]. Traditional knee-injury prevention focuses on the knee itself [4,5]. ...

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Rethinking knee injury prevention strategies: joint-by-joint training approach paradigm versus traditional focused knee strengthening

... Having direct measures of muscle length trajectory offers the opportunity to expose muscles to temporally appropriate lengthening and shortening velocities, which are known to affect the force-generating capacity of a muscle and consequently the power produced (Askew andMarsh, 1997, 1998). These data are typically acquired using sonomicrometry (Ross et al., 2024), fluoromicrometry (Camp et al., 2016) or magnetomicrometry (Taylor et al., 2021) and provide unequivocal readouts of fibre length changes. Equally, EMGderived stimulation duration and phase are known to significantly alter predictions of muscle performance (Altringham and Johnston, 1990;Josephson, 1985a;Rice et al., 2023). ...

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The importance of muscle activation on the interpretation of muscle mechanical performance

... The calf musculature, consisting of the soleus (SOL), gastrocnemius (GAS) and plantaris (PLA) muscles, is often used as a research subject in muscle experiments (Lieber and Blevins, 1989;Gareis et al., 1992;Herzog et al., 1994;Prilutsky et al., 1996;Siebert et al., 2015;Baggaley et al., 2024). The single-joint SOL contributes to the generation of torque in the ankle joint. ...

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Age-dependent properties of the rabbit calf musculature—Relationship between mechanic and microstructure

... Electron microscopies, on the other hand, provide very-high resolutions to visualise and resolve collagen fibrils; however, their restricted field of view (FoV) and the extensive sample preparation impede the ability to examine the structural responses to load over the entire tissue depth [9,18,19]. Widefield polarized light microscopy leverages birefringence to detect and visualize broad patterns of light transmission influenced by the anisotropy of the sample, offering an overview of collagen organization [20]. However, its effectiveness is influenced by sample thickness, often necessitating delicate tissue sectioning, the effects of which on imaging outcomes remain uncertain. ...

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Zonal Characteristics of Collagen Ultrastructure and Responses to Mechanical Loading in Articular Cartilage

... de Brito Fontana et al. (1) argued that statistical differences between data captured using longitudinal versus transverse scans "seem to suggest the observed changes in EI are not determined by the changes in fascicle angle." We anticipated such differences because tissue direction affects sound reflection direction. ...

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