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Walter T, Stutzig N, Siebert T. Active exoskeleton reduces erector spinae muscle activity during lifting. Front Bioeng Biotechnol 2023; 11:1143926. [PMID: 37180043 PMCID: PMC10168292 DOI: 10.3389/fbioe.2023.1143926] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Accepted: 04/10/2023] [Indexed: 05/15/2023] Open
Abstract
Musculoskeletal disorders (MSD) are a widespread problem, often regarding the lumbar region. Exoskeletons designed to support the lower back could be used in physically demanding professions with the intention of reducing the strain on the musculoskeletal system, e.g., by lowering task-related muscle activation. The present study aims to investigate the effect of an active exoskeleton on back muscle activity when lifting weights. Within the framework of the study, 14 subjects were asked to lift a 15 kg box with and without an active exoskeleton which allows the adjustment of different levels of support, while the activity of their M. erector spinae (MES) was measured using surface electromyography. Additionally, the subjects were asked about their overall rating of perceived exertion (RPE) during lifting under various conditions. Using the exoskeleton with the maximum level of support, the muscle activity was significantly lower than without exoskeleton. A significant correlation was found between the exoskeleton's support level and the reduction of MES activity. The higher the support level, the lower the observed muscle activity. Furthermore, when lifting with the maximum level of support, RPE was found to be significantly lower than without exoskeleton too. A reduction in the MES activity indicates actual support for the movement task and might indicate lower compression forces in the lumbar region. It is concluded that the active exoskeleton supports people noticeably when lifting heavy weights. Exoskeletons seem to be a powerful tool for reducing load during physically demanding jobs and thus, their use might be helpful in lowering the risk of MSD.
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Affiliation(s)
- Tobias Walter
- Motion and Exercise Science, University of Stuttgart, Stuttgart, Germany
| | - Norman Stutzig
- Motion and Exercise Science, University of Stuttgart, Stuttgart, Germany
| | - Tobias Siebert
- Motion and Exercise Science, University of Stuttgart, Stuttgart, Germany
- Stuttgart Center for Simulation Science, University of Stuttgart, Stuttgart, Germany
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2
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Kempter F, Lantella L, Stutzig N, Fehr J, Siebert T. Role of Rotated Head Postures on Volunteer Kinematics and Muscle Activity in Braking Scenarios Performed on a Driving Simulator. Ann Biomed Eng 2023; 51:771-782. [PMID: 36224484 PMCID: PMC10023650 DOI: 10.1007/s10439-022-03087-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2022] [Accepted: 09/20/2022] [Indexed: 11/01/2022]
Abstract
Occupants exposed to low or moderate crash events can already suffer from whiplash-associated disorders leading to severe and long-lasting symptoms. However, the underlying injury mechanisms and the role of muscle activity are not fully clear. Potential increases in injury risk of non-nominal postures, i.e., rotated head, cannot be evaluated in detail due to the lack of experimental data. Examining changes in neck muscle activity to hold and stabilize the head in a rotated position during pre-crash scenarios might provide a deeper understanding of muscle reflex contributions and injury mechanisms. In this study, the influence of two different head postures (nominal vs. rotation of the head by about 63 ± 9° to the right) on neck muscle activity and head kinematics was investigated in simulated braking experiments inside a driving simulator. The braking scenario was implemented by visualization of the virtual scene using head-mounted displays and a combined translational-rotational platform motion. Kinematics of seventeen healthy subjects was tracked using 3D motion capturing. Surface electromyography were used to quantify muscle activity of left and right sternocleidomastoideus (SCM) and trapezius (TRP) muscles. The results show clear evidence that rotated head postures affect the static as well as the dynamic behavior of muscle activity during the virtual braking event. With head turned to the right, the contralateral left muscles yielded higher base activation and delayed muscle onset times. In contrast, right muscles had much lower activations and showed no relevant changes in muscle activation between nominal and rotated head position. The observed delayed muscle onset times and increased asymmetrical muscle activation patterns in the rotated head position are assumed to affect injury mechanisms. This could explain the prevalence of rotated head postures during a crash reported by patients suffering from WAD. The results can be used for validating the active behavior of human body models in braking simulations with nominal and rotated head postures, and to gain a deeper understanding of neck injury mechanisms.
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Affiliation(s)
- Fabian Kempter
- Institute of Engineering and Computational Mechanics, University of Stuttgart, Pfaffenwaldring 9, 70569, Stuttgart, Germany
| | - Lorena Lantella
- Institute of Sport and Movement Science, University of Stuttgart, Allmandring 28, 70569, Stuttgart, Germany
| | - Norman Stutzig
- Institute of Sport and Movement Science, University of Stuttgart, Allmandring 28, 70569, Stuttgart, Germany
| | - Jörg Fehr
- Institute of Engineering and Computational Mechanics, University of Stuttgart, Pfaffenwaldring 9, 70569, Stuttgart, Germany.
| | - Tobias Siebert
- Institute of Sport and Movement Science, University of Stuttgart, Allmandring 28, 70569, Stuttgart, Germany
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3
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Klaiber LR, Schlechtweg S, Wiedemann R, Alt W, Stutzig N. Local displacement within the Achilles tendon induced by electrical stimulation of the single gastrocnemius muscles. Clin Biomech (Bristol, Avon) 2023; 102:105901. [PMID: 36791484 DOI: 10.1016/j.clinbiomech.2023.105901] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/12/2022] [Revised: 01/13/2023] [Accepted: 01/26/2023] [Indexed: 02/17/2023]
Abstract
BACKGROUND The Achilles tendon consists of three subtendons, but their functional meaning is still unknown. There are several approaches for the examination in-vivo using sonographic imaging, however, there is no approach for in-vivo examination with respect to the single subtendons of the m. triceps surae. The study's aim was to reveal the single subtendons of the m. triceps surae. METHODS The Achilles tendon of 17 subjects was analysed. The muscles (m. gastrocnemius lateralis and medialis) were stimulated separately using neuromuscular electrical stimulation. The intensity of muscle contraction was controlled using electromyographic data. Sonographic videos of the Achilles tendon were recorded during muscle contraction. A speckle tracking algorithm was used to analyse the moving areas within the Achilles tendon during the initial phase of contraction. FINDINGS The muscles were activated at 10-20% of the maximal M-wave. Isolated contraction of m. gastrocnemius lateralis led to local displacement in the lateral part of the Achilles tendon's cross-section whereas isolated contraction of m. gastrocnemius medialis led to displacement in the medial part and to a larger size of the area where initial displacement took place (m. gastrocnemius lateralis to medialis approximately 1:2). INTERPRETATION The results demonstrate that isolated contractions of m. gastrocnemius lateralis and medialis lead to individual displacements which significantly differ. The differences in position and size of the area of the local displacement indicate an independent individual function. Unlike other studies generally investigating the AT in-vivo using muscle stimulation and ultrasonic imaging, this study investigated the AT's cross-section which had never been investigated before.
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Affiliation(s)
| | - Sascha Schlechtweg
- Institute of Sport and Movement Science, University of Stuttgart, Germany
| | - Rika Wiedemann
- Institute of Sport and Movement Science, University of Stuttgart, Germany
| | - Wilfried Alt
- Institute of Sport and Movement Science, University of Stuttgart, Germany
| | - Norman Stutzig
- Institute of Sport and Movement Science, University of Stuttgart, Germany
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Nitzsche N, Siebert T, Schulz H, Stutzig N. Effect of plyometric training on dynamic leg strength and jumping performance in rhythmic gymnastics: A preliminary study. ISOKINET EXERC SCI 2022. [DOI: 10.3233/ies-210148] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND: Reactive performance is an important component of rhythmic gymnastics. So far, it is unclear whether additional plyometric training in female gymnasts shows an increase in performance. OBJECTIVE: The aim of the study was to examine the effect of additional plyometric training in rhythmic gymnastics on the reactive jumping performance and strength of the lower leg muscles. METHODS: Fifteen rhythmic gymnasts (age: 12.3 ± 2.6 years, height: 1.47 ± 0.12 m, body weight: 37.3 ± 9.3 kg, BMI: 16.7 ± 2.1 kg*m-2; competition level: national and international championships, Tanner stages I–III) participated in the study. The athletes were assigned to an experimental (EG) and a control group (CG). The EG performed plyometric exercises three times per week in addition to the regular training. Before and after six weeks of training the reactive jump performance, the work of dorsi flexors and plantar flexors performed during isokinetic plantarflexion, as well as the performance in two sport-specific tests were measured. RESULTS: In contrast to the CG, in the EG the jump height (pre: 24.8; post: 27.25 cm; p< 0.05) and the reactive-strength-index (pre: 1.01; post: 1.19; p< 0.01) increased significantly. The EG achieved significant improvements in the counter movement jump test (pre: 27.0 cm; post: 31.5 cm; p< 0.01) and in the sport specific double rope jump test (jumps per minute, pre: 18.0; post: 23.0; p< 0.01). Furthermore, a significant increase in work performed during plantarflexion was found in the EG for the right leg (pre: 24.9 J; post: 29.7 J; p< 0.01) and a tendency to increase for the left leg (pre: 26.4 J; post: 37.7 J; p= 0.05). CONCLUSION: Both reactive strength and dynamic force can be efficiently increased by plyometric training. It may be recommended to include plyometric exercises in the training regime of rhythmic gymnasts.
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Affiliation(s)
- Nico Nitzsche
- Department of Sports Medicine/Sports Biology, Institute of Human Movement Science and Health, Technische Universität Chemnitz, Chemnitz, Germany
| | - Tobias Siebert
- Department of Motion and Exercise Science, Institute of Sport and Movement Science, University of Stuttgart, Stuttgart, Germany
| | - Henry Schulz
- Department of Sports Medicine/Sports Biology, Institute of Human Movement Science and Health, Technische Universität Chemnitz, Chemnitz, Germany
| | - Norman Stutzig
- Department of Motion and Exercise Science, Institute of Sport and Movement Science, University of Stuttgart, Stuttgart, Germany
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Fuchs K, Krauskopf T, Lauck TB, Klein L, Mueller M, Herget GW, Von Tscharner V, Stutzig N, Stieglitz T, Pasluosta C. Influence of Augmented Visual Feedback on Balance Control in Unilateral Transfemoral Amputees. Front Neurosci 2021; 15:727527. [PMID: 34588950 PMCID: PMC8473899 DOI: 10.3389/fnins.2021.727527] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Accepted: 08/24/2021] [Indexed: 11/16/2022] Open
Abstract
Patients with a lower limb amputation rely more on visual feedback to maintain balance than able-bodied individuals. Altering this sensory modality in amputees thus results in a disrupted postural control. However, little is known about how lower limb amputees cope with augmented visual information during balance tasks. In this study, we investigated how unilateral transfemoral amputees incorporate visual feedback of their center of pressure (CoP) position during quiet standing. Ten transfemoral amputees and ten age-matched able-bodied participants were provided with real-time visual feedback of the position of their CoP while standing on a pressure platform. Their task was to keep their CoP within a small circle in the center of a computer screen placed at eye level, which could be achieved by minimizing their postural sway. The visual feedback was then delayed by 250 and 500 ms and was combined with a two- and five-fold amplification of the CoP displacements. Trials with eyes open without augmented visual feedback as well as with eyes closed were further performed. The overall performance was measured by computing the sway area. We further quantified the dynamics of the CoP adjustments using the entropic half-life (EnHL) to study possible physiological mechanisms behind postural control. Amputees showed an increased sway area compared to the control group. The EnHL values of the amputated leg were significantly higher than those of the intact leg and the dominant and non-dominant leg of controls. This indicates lower dynamics in the CoP adjustments of the amputated leg, which was compensated by increasing the dynamics of the CoP adjustments of the intact leg. Receiving real-time visual feedback of the CoP position did not significantly reduce the sway area neither in amputees nor in controls when comparing with the eyes open condition without visual feedback of the CoP position. Further, with increasing delay and amplification, both groups were able to compensate for small visual perturbations, yet their dynamics were significantly lower when additional information was not received in a physiologically relevant time frame. These findings may be used for future design of neurorehabilitation programs to restore sensory feedback in lower limb amputees.
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Affiliation(s)
- Katharina Fuchs
- Department of Microsystems Engineering, Laboratory for Biomedical Microtechnology, University of Freiburg, Freiburg im Breisgau, Germany
| | - Thomas Krauskopf
- Department of Microsystems Engineering, Laboratory for Biomedical Microtechnology, University of Freiburg, Freiburg im Breisgau, Germany.,BrainLinks-BrainTools, University of Freiburg, Freiburg im Breisgau, Germany
| | - Torben B Lauck
- Department of Microsystems Engineering, Laboratory for Biomedical Microtechnology, University of Freiburg, Freiburg im Breisgau, Germany
| | - Lukas Klein
- Department of Orthopedics and Trauma Surgery, Medical Center, Faculty of Medicine, University of Freiburg, Freiburg im Breisgau, Germany
| | - Marc Mueller
- Sanitätshaus Pfänder, Freiburg im Breisgau, Germany
| | - Georg W Herget
- Department of Orthopedics and Trauma Surgery, Medical Center, Faculty of Medicine, University of Freiburg, Freiburg im Breisgau, Germany
| | | | - Norman Stutzig
- Department of Motion and Exercise Science, University of Stuttgart, Stuttgart, Germany
| | - Thomas Stieglitz
- Department of Microsystems Engineering, Laboratory for Biomedical Microtechnology, University of Freiburg, Freiburg im Breisgau, Germany.,BrainLinks-BrainTools, University of Freiburg, Freiburg im Breisgau, Germany.,Bernstein Center Freiburg, University of Freiburg, Freiburg im Breisgau, Germany
| | - Cristian Pasluosta
- Department of Microsystems Engineering, Laboratory for Biomedical Microtechnology, University of Freiburg, Freiburg im Breisgau, Germany
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6
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Ryan DS, Stutzig N, Helmer A, Siebert T, Wakeling JM. The Effect of Multidirectional Loading on Contractions of the M. Medial Gastrocnemius. Front Physiol 2021; 11:601799. [PMID: 33536934 PMCID: PMC7848218 DOI: 10.3389/fphys.2020.601799] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Accepted: 12/16/2020] [Indexed: 11/13/2022] Open
Abstract
Research has shown that compression of muscle can lead to a change in muscle force. Most studies show compression to lead to a reduction in muscle force, although recent research has shown that increases are also possible. Based on methodological differences in the loading design between studies, it seems that muscle length and the direction of transverse loading influence the effect of muscle compression on force production. Thus, in our current study we implement these two factors to influence the effects of muscle loading. In contrast to long resting length of the medial gastrocnemius (MG) in most studies, we use a shorter MG resting length by having participant seated with their knees at a 90° angle. Where previous studies have used unidirectional loads to compress the MG, in this study we applied a multidirectional load using a sling setup. Multidirectional loading using a sling setup has been shown to cause muscle force reductions in previous research. As a result of our choices in experimental design we observed changes in the effects of muscle loading compared to previous research. In the present study we observed no changes in muscle force due to muscle loading. Muscle thickness and pennation angle showed minor but significant increases during contraction. However, no significant changes occurred between unloaded and loaded trials. Fascicle thickness and length showed different patterns of change compared to previous research. We show that muscle loading does not result in force reduction in all situations and is possibly linked to differences in muscle architecture and muscle length.
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Affiliation(s)
- David S Ryan
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, Canada
| | - Norman Stutzig
- Department of Motion and Exercise Science, University of Stuttgart, Stuttgart, Germany
| | - Andreas Helmer
- Department of Motion and Exercise Science, University of Stuttgart, Stuttgart, Germany
| | - Tobias Siebert
- Department of Motion and Exercise Science, University of Stuttgart, Stuttgart, Germany
| | - James M Wakeling
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, Canada
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7
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Haeufle DFB, Siegel J, Hochstein S, Gussew A, Schmitt S, Siebert T, Rzanny R, Reichenbach JR, Stutzig N. Energy Expenditure of Dynamic Submaximal Human Plantarflexion Movements: Model Prediction and Validation by in-vivo Magnetic Resonance Spectroscopy. Front Bioeng Biotechnol 2020; 8:622. [PMID: 32671034 PMCID: PMC7332772 DOI: 10.3389/fbioe.2020.00622] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Accepted: 05/21/2020] [Indexed: 11/30/2022] Open
Abstract
To understand the organization and efficiency of biological movement, it is important to evaluate the energy requirements on the level of individual muscles. To this end, predicting energy expenditure with musculoskeletal models in forward-dynamic computer simulations is currently the most promising approach. However, it is challenging to validate muscle models in-vivo in humans, because access to the energy expenditure of single muscles is difficult. Previous approaches focused on whole body energy expenditure, e.g., oxygen consumption (VO2), or on thermal measurements of individual muscles by tracking blood flow and heat release (through measurements of the skin temperature). This study proposes to validate models of muscular energy expenditure by using functional phosphorus magnetic resonance spectroscopy (31P-MRS). 31P-MRS allows to measure phosphocreatine (PCr) concentration which changes in relation to energy expenditure. In the first 25 s of an exercise, PCr breakdown rate reflects ATP hydrolysis, and is therefore a direct measure of muscular enthalpy rate. This method was applied to the gastrocnemius medialis muscle of one healthy subject during repetitive dynamic plantarflexion movements at submaximal contraction, i.e., 20% of the maximum plantarflexion force using a MR compatible ergometer. Furthermore, muscle activity was measured by surface electromyography (EMG). A model (provided as open source) that combines previous models for muscle contraction dynamics and energy expenditure was used to reproduce the experiment in simulation. All parameters (e.g., muscle length and volume, pennation angle) in the model were determined from magnetic resonance imaging or literature (e.g., fiber composition), leaving no free parameters to fit the experimental data. Model prediction and experimental data on the energy supply rates are in good agreement with the validation phase (<25 s) of the dynamic movements. After 25 s, the experimental data differs from the model prediction as the change in PCr does not reflect all metabolic contributions to the energy expenditure anymore and therefore underestimates the energy consumption. This shows that this new approach allows to validate models of muscular energy expenditure in dynamic movements in vivo.
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Affiliation(s)
- Daniel F B Haeufle
- Multi-level Modeling in Motor Control and Rehabilitation Robotics, Hertie Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany
| | - Johannes Siegel
- Multi-level Modeling in Motor Control and Rehabilitation Robotics, Hertie Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany.,Department of Motion and Exercise Science, Institute of Sport and Movement Science, University of Stuttgart, Stuttgart, Germany
| | - Stefan Hochstein
- Motion Science, Institute of Sport Science, Martin-Luther-University Halle, Halle, Germany
| | - Alexander Gussew
- Department of Radiology, University Hospital Halle (Saale), Halle, Germany
| | - Syn Schmitt
- Computational Biophysics and Biorobotics, Institute for Modelling and Simulation of Biomechanical Systems, University of Stuttgart, Stuttgart, Germany.,Stuttgart Center of Simulation Science, University of Stuttgart, Stuttgart, Germany
| | - Tobias Siebert
- Department of Motion and Exercise Science, Institute of Sport and Movement Science, University of Stuttgart, Stuttgart, Germany
| | - Reinhard Rzanny
- Medical Physics Group, Institute of Diagnostic and Interventional Radiology, Jena University Hospital - Friedrich Schiller University, Jena, Germany
| | - Jürgen R Reichenbach
- Medical Physics Group, Institute of Diagnostic and Interventional Radiology, Jena University Hospital - Friedrich Schiller University, Jena, Germany
| | - Norman Stutzig
- Department of Motion and Exercise Science, Institute of Sport and Movement Science, University of Stuttgart, Stuttgart, Germany
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8
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Rockenfeller R, Günther M, Stutzig N, Haeufle DFB, Siebert T, Schmitt S, Leichsenring K, Böl M, Götz T. Exhaustion of Skeletal Muscle Fibers Within Seconds: Incorporating Phosphate Kinetics Into a Hill-Type Model. Front Physiol 2020; 11:306. [PMID: 32431619 PMCID: PMC7214688 DOI: 10.3389/fphys.2020.00306] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Accepted: 03/19/2020] [Indexed: 12/01/2022] Open
Abstract
Initiated by neural impulses and subsequent calcium release, skeletal muscle fibers contract (actively generate force) as a result of repetitive power strokes of acto-myosin cross-bridges. The energy required for performing these cross-bridge cycles is provided by the hydrolysis of adenosine triphosphate (ATP). The reaction products, adenosine diphosphate (ADP) and inorganic phosphate (P i ), are then used-among other reactants, such as creatine phosphate-to refuel the ATP energy storage. However, similar to yeasts that perish at the hands of their own waste, the hydrolysis reaction products diminish the chemical potential of ATP and thus inhibit the muscle's force generation as their concentration rises. We suggest to use the term "exhaustion" for force reduction (fatigue) that is caused by combined P i and ADP accumulation along with a possible reduction in ATP concentration. On the basis of bio-chemical kinetics, we present a model of muscle fiber exhaustion based on hydrolytic ATP-ADP-P i dynamics, which are assumed to be length- and calcium activity-dependent. Written in terms of differential-algebraic equations, the new sub-model allows to enhance existing Hill-type excitation-contraction models in a straightforward way. Measured time courses of force decay during isometric contractions of rabbit M. gastrocnemius and M. plantaris were employed for model verification, with the finding that our suggested model enhancement proved eminently promising. We discuss implications of our model approach for enhancing muscle models in general, as well as a few aspects regarding the significance of phosphate kinetics as one contributor to muscle fatigue.
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Affiliation(s)
| | - Michael Günther
- Institute for Modelling and Simulation of Biomechanical Systems, Computational Biophysics and Biorobotics, University of Stuttgart, Stuttgart, Germany
- Friedrich-Schiller-University, Jena, Germany
| | - Norman Stutzig
- Department of Motion and Exercise Science, University of Stuttgart, Stuttgart, Germany
| | - Daniel F. B. Haeufle
- Hertie-Institute for Clinical Brain Research and Center for Integrative Neuroscience, Eberhard-Karls-University, Tübingen, Germany
| | - Tobias Siebert
- Department of Motion and Exercise Science, University of Stuttgart, Stuttgart, Germany
| | - Syn Schmitt
- Institute for Modelling and Simulation of Biomechanical Systems, Computational Biophysics and Biorobotics, University of Stuttgart, Stuttgart, Germany
| | - Kay Leichsenring
- Institute of Solid Mechanics, Technical University Braunschweig, Braunschweig, Germany
| | - Markus Böl
- Institute of Solid Mechanics, Technical University Braunschweig, Braunschweig, Germany
| | - Thomas Götz
- Mathematical Institute, University of Koblenz-Landau, Koblenz, Germany
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9
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Siebert T, Donath L, Borsdorf M, Stutzig N. Effect of Static Stretching, Dynamic Stretching, and Myofascial Foam Rolling on Range of Motion During Hip Flexion: A Randomized Crossover Trial. J Strength Cond Res 2020; 36:680-685. [PMID: 34379375 DOI: 10.1519/jsc.0000000000003517] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Siebert, T, Donath, L, Borsdorf, M, and Stutzig, N. Effect of static stretching, dynamic stretching, and myofascial foam rolling on range of motion during hip flexion: A randomized crossover trial. J Strength Cond Res XX(X): 000-000, 2020-Static and dynamic stretching (DS) are commonly used in sports and physical therapy to increase the range of motion (ROM). However, prolonged static stretching (SS) can deteriorate athletic performance. Alternative methods to increase ROM are thus needed. Foam rolling (FR) may initiate muscle relaxation, improve muscular function, physical performance, and ROM. Previous studies that examined effects of FR on ROM did not control for increased tissue compliance or shifted pain threshold. In this study, the isolated influence of altered tissue compliance on ROM after FR, SS, and DS was investigated using a randomized crossover design. Hip flexion ROM at given joint torques before and after SS, DS, and FR was randomly assessed in 14 young male adults (age: 23.7 +/- 1.3 years; height: 182 +/- 8 cm; body mass: 79.4 +/- 6.9 kg). Hip flexion ROM was measured in the sagittal plane with the subjects lying in a lateral position (no gravitational effects on ROM measurements). Surface electromyographic (EMG) analysis of 2 representative hip extensors (M. biceps femoris and M. semitendinosus) was applied to control for active muscle contribution during ROM measurements. Significant increases in ROM for SS (3.8 +/- 1.1[degrees]; p < 0.001) and DS (3.7 +/- 1.8[degrees]; p < 0.001) were observed, but not for FR (0.8 +/- 3.1[degrees]; p = 0.954). Because stretch forces on tendon and muscle tissue during SS and DS predominately act in longitudinal direction, FR induces mainly transversal forces in the muscle tissue. Thus, increased ROM after FR reported in the literature is more likely due to a shift in the pain threshold. These results provide a better understanding of differential loading conditions during SS, DS, and FR for coaches and practitioners.
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Affiliation(s)
- Tobias Siebert
- Department of Motion and Exercise Science, University of Stuttgart, Stuttgart, Germany
| | - Lars Donath
- Department of Intervention Research in Exercise Training, German Sport University Cologne, Cologne, Germany
| | - Mischa Borsdorf
- Department of Motion and Exercise Science, University of Stuttgart, Stuttgart, Germany
| | - Norman Stutzig
- Department of Motion and Exercise Science, University of Stuttgart, Stuttgart, Germany
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Scharschmidt R, Derlien S, Siebert T, Herbsleb M, Stutzig N. Intraday and interday reliability of pelvic floor muscles electromyography in continent woman. Neurourol Urodyn 2019; 39:271-278. [PMID: 31642114 DOI: 10.1002/nau.24187] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2019] [Accepted: 10/02/2019] [Indexed: 11/08/2022]
Abstract
AIMS Vaginal surface electromyography (sEMG) is a tool used for the diagnosis and therapeutic intervention of urinary incontinence. Current sEMG systems differ in regard to electrode arrangement and data reproducibility. The aim of this study was to determine the intrasession, intraday, and interday reliabilities of sEMG parameters using a probe with circumferential electrode-position. METHODS The intrasession, intraday, and interday reliabilities of maximum isometric voluntary contractions (MVC) of the pelvic floor muscles were assessed for 19 healthy continent women. Three sEMG parameters that are used to describe muscle activity were verified: maximal EMG (EMGmax ), mean over 500 ms around EMGmax (EMGA0.5 ), and mean over 2 seconds during MVC plateau (EMGA2-4 ). Relative and absolute reliability parameters were calculated, and the statistical methods described by Bland and Altman were applied to the data. RESULTS We observed substantial reliabilities for all obtained parameters (EMGmax , EMGA2-4 , and EMGA0.5 ) in regard to the intrasession measurements (ICC = 0.93-0.97; CI = 0.86-0.99). Overall, the intraday reliability has been moderate (ICC = 0.64-0.75; CI = 0.27-0.90). EMGmax (ICC = 0.75; CI = 0.45-0.90) and EMGA2-4 (ICC = 0.73, CI = 0.42-0.89) were higher than EMGA0.5 (ICC = 0.64; CI = 0.27-0.85). However, the interday reliability was only fair for EMGmax (ICC = 0.48; CI = 0.04-0.77) and EMGA0.5 (ICC = 0.51; CI = 0.07-0.78) but moderate for EMGA2-4 (ICC = 0.65; CI = 0.28-0.85). CONCLUSIONS This intrasession, intraday, and interday reliability results are similar to the results reported in the literature using probes with longitudinally oriented bars. The mean sEMG signal over 2 seconds (EMGA2-4 ) exhibited the highest reliability and is recommended for further studies. The interday reliability might be enhanced by considering the menstruation cycle.
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Affiliation(s)
| | - Steffen Derlien
- Institute of Physiotherapy, University Hospital Jena, Jena, Germany
| | - Tobias Siebert
- Institute of Sport and Movement Science, University of Stuttgart, Stuttgart, Germany
| | - Marco Herbsleb
- Department of Sports Medicine and Health Promotion, University of Jena, Jena, Germany
| | - Norman Stutzig
- Institute of Sport and Movement Science, University of Stuttgart, Stuttgart, Germany
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11
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Ryan DS, Stutzig N, Siebert T, Wakeling JM. Passive and dynamic muscle architecture during transverse loading for gastrocnemius medialis in man. J Biomech 2019; 86:160-166. [PMID: 30792071 DOI: 10.1016/j.jbiomech.2019.01.054] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2018] [Revised: 01/20/2019] [Accepted: 01/31/2019] [Indexed: 11/24/2022]
Abstract
External forces from our environment impose transverse loads on our muscles. Studies in rats have shown that transverse loads result in a decrease in the longitudinal muscle force. Changes in muscle architecture during contraction may contribute to the observed force decrease. The aim of this study was to quantify changes in pennation angle, fascicle dimensions, and muscle thickness during contraction under external transverse load. Electrical stimuli were elicited to evoke maximal force twitches in the right calf muscles of humans. Trials were conducted with transverse loads of 2, 4.5, and 10 kg. An ultrasound probe was placed on the medial gastrocnemius in line with the transverse load to quantify muscle characteristics during muscle twitches. Maximum twitch force decreased with increased transverse muscle loading. The 2, 4.5, and 10 kg of transverse load showed a 9, 13, and 16% decrease in longitudinal force, respectively. Within the field of view of the ultrasound images, and thus directly beneath the external load, loading of the muscle resulted in a decrease in the muscle thickness and pennation angle, with higher loads causing greater decreases. During twitches the muscle transiently increased in thickness and pennation angle, as did fascicle thickness. Higher transverse loads showed a reduced increase in muscle thickness. Smaller increases in pennation angle and fascicle thickness strain also occurred with higher transverse loads. This study shows that increased transverse loading caused a decrease in ankle moment, muscle thickness, and pennation angle, as well as transverse deformation of the fascicles.
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Affiliation(s)
- David S Ryan
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, Canada.
| | - Norman Stutzig
- Department of Motion and Exercise Science, University of Stuttgart, Germany
| | - Tobias Siebert
- Department of Motion and Exercise Science, University of Stuttgart, Germany
| | - James M Wakeling
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, Canada
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12
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Borsdorf M, Tomalka A, Stutzig N, Morales-Orcajo E, Böl M, Siebert T. Locational and Directional Dependencies of Smooth Muscle Properties in Pig Urinary Bladder. Front Physiol 2019; 10:63. [PMID: 30787883 PMCID: PMC6372509 DOI: 10.3389/fphys.2019.00063] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Accepted: 01/21/2019] [Indexed: 12/11/2022] Open
Abstract
The urinary bladder is a distensible hollow muscular organ, which allows huge changes in size during absorption, storage and micturition. Pathological alterations of biomechanical properties can lead to bladder dysfunction and loss in quality of life. To understand and treat bladder diseases, the mechanisms of the healthy urinary bladder need to be determined. Thus, a series of studies focused on the detrusor muscle, a layer of urinary bladder made of smooth muscle fibers arranged in longitudinal and circumferential orientation. However, little is known about whether its active muscle properties differ depending on location and direction. This study aimed to investigate the porcine bladder for heterogeneous (six different locations) and anisotropic (longitudinal vs. circumferential) contractile properties including the force-length-(FLR) and force-velocity-relationship (FVR). Therefore, smooth muscle tissue strips with longitudinal and circumferential direction have been prepared from different bladder locations (apex dorsal, apex ventral, body dorsal, body ventral, trigone dorsal, trigone ventral). FLR and FVR have been determined by a series of isometric and isotonic contractions. Additionally, histological analyses were conducted to determine smooth muscle content and fiber orientation. Mechanical and histological examinations were carried out on 94 and 36 samples, respectively. The results showed that maximum active stress (pact ) of the bladder strips was higher in the longitudinal compared to the circumferential direction. This is in line with our histological investigation showing a higher smooth muscle content in the bladder strips in the longitudinal direction. However, normalization of maximum strip force by the cross-sectional area (CSA) of smooth muscle fibers yielded similar smooth muscle maximum stresses (165.4 ± 29.6 kPa), independent of strip direction. Active muscle properties (FLR, FVR) showed no locational differences. The trigone exhibited higher passive stress (ppass ) than the body. Moreover, the bladder exhibited greater ppass in the longitudinal than circumferential direction which might be attributed to its microstructure (more longitudinal arrangement of muscle fibers). This study provides a valuable dataset for the development of constitutive computational models of the healthy urinary bladder. These models are relevant from a medical standpoint, as they contribute to the basic understanding of the function of the bladder in health and disease.
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Affiliation(s)
- Mischa Borsdorf
- Institute for Sport and Exercise Science, Department of Movement and Exercise Science, University of Stuttgart, Stuttgart, Germany
| | - André Tomalka
- Institute for Sport and Exercise Science, Department of Movement and Exercise Science, University of Stuttgart, Stuttgart, Germany
| | - Norman Stutzig
- Institute for Sport and Exercise Science, Department of Movement and Exercise Science, University of Stuttgart, Stuttgart, Germany
| | - Enrique Morales-Orcajo
- Institute of Solid Mechanics, Department of Mechanical Engineering, Technical University of Braunschweig, Braunschweig, Germany
| | - Markus Böl
- Institute of Solid Mechanics, Department of Mechanical Engineering, Technical University of Braunschweig, Braunschweig, Germany
| | - Tobias Siebert
- Institute for Sport and Exercise Science, Department of Movement and Exercise Science, University of Stuttgart, Stuttgart, Germany
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13
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Stutzig N, Ryan D, Wakeling JM, Siebert T. Impact of transversal calf muscle loading on plantarflexion. J Biomech 2019; 85:37-42. [PMID: 30660380 DOI: 10.1016/j.jbiomech.2019.01.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2018] [Revised: 11/22/2018] [Accepted: 01/03/2019] [Indexed: 11/29/2022]
Abstract
Muscle compression commonly occurs in daily life (for instance wearing backpacks or compression garments, and during sitting). However, the effects of the compression on contraction dynamics in humans are not well examined. The aim of the study was to quantify the alterations of contraction dynamics and muscle architecture in human muscle with external transverse loads. The posterior tibialis nerve of 29 subjects was stimulated to obtain the maximal double-twitch force of the gastrocnemius muscle with and without transverse compression that was generated using an indentor. The muscle architecture was determined by a sonographic probe that was embedded within the indentor. Five stimulations each were conducted at 5 conditions: (1) pretest (unloaded), (2) indentor loading with 2 kg, (3) 4.5 kg, (4) 10 kg, and (5) posttest (unloaded). Compared to the pretest maximal force decreased by 9%, 13% and 16% for 2 kg, 4.5 kg and 10 kg, respectively. The half-relaxation time increased with increased transverse load whereas the rate of force development decreased from pretest to 2 kg and from 4.5 kg to 10 kg. The lifting height of the indentor increased with transverse load from 2 kg to 4.5 kg but decreased from 4.5 kg to 10 kg. Increases in pennation during the twitches were reduced at the highest transverse load. The results demonstrate changes of the contraction dynamics due to transversal muscle loading. Those alterations are associated with the applied pressure, changes in muscle architecture and partitioning of muscle force in transversal and longitudinal direction.
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Affiliation(s)
- Norman Stutzig
- Department of Motion and Exercise Science, University of Stuttgart, Germany.
| | - David Ryan
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Vancouver, Canada
| | - James M Wakeling
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Vancouver, Canada
| | - Tobias Siebert
- Department of Motion and Exercise Science, University of Stuttgart, Germany
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14
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Siebert T, Eb M, Ryan DS, Wakeling JM, Stutzig N. Impact of Multidirectional Transverse Calf Muscle Loading on Calf Muscle Force in Young Adults. Front Physiol 2018; 9:1148. [PMID: 30174622 PMCID: PMC6107699 DOI: 10.3389/fphys.2018.01148] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2018] [Accepted: 07/31/2018] [Indexed: 11/13/2022] Open
Abstract
It has been demonstrated that unidirectional transversal muscle loading induced by a plunger influences muscle shape and reduces muscle force. The interaction between muscle and transversal forces may depend on specific neuromuscular properties that change during a lifetime. Compression garments, applying forces from all directions in the transverse plane, are widely used in sports for example to improve performance. Differences in the loading direction (unidirectional vs. multidirectional) may have an impact on force generating capacity of muscle and, thus, on muscle performance. The aim of this study was to examine the effect of multidirectional transversal loads, using a sling looped around the calf, on the isometric force during plantarflexions. Young male adults (25.7 ± 1.5 years, n = 15) were placed in a prone position in a calf press apparatus. The posterior tibial nerve was stimulated to obtain the maximal double-twitch force of the calf muscles with (59.4 and 108.4 N) and without multidirectional transverse load. Compared to the unloaded condition, the rate of force development (RFD) was reduced by 5.0 ± 8.1% (p = 0.048) and 6.9 ± 10.7% (p = 0.008) for the 59.4 and 108.4 N load, respectively. No significant reduction (3.2 ± 4.8%, p = 0.141) in maximum muscle force (Fm ) was found for the lower load (59.4 N), but application of the higher load (108.4 N) resulted in a significant reduction of Fm by 4.8 ± 7.0% (p = 0.008). Mean pressures induced in this study (14.3 and 26.3 mm Hg corresponding to the 59.4 and 108.4 N loads, respectively) are within the pressure range reported for compression garments. Taking the results of the present study into account, a reduction in maximum muscle force would be expected for compression garments with pressures ≥26.3 mm Hg. However, it should be noted that the loading condition (sling vs. compression garment) differs and that compression garments may influence other mechanisms contributing to force generation. For example, wearing compression garments may enhance sport performance by enhanced proprioception and reduced muscle oscillation. Thus, superposition of several effects should be considered when analyzing the impact of compression garments on more complex sport performance.
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Affiliation(s)
- Tobias Siebert
- Department of Motion and Exercise Science, University of Stuttgart, Stuttgart, Germany
| | - Manuel Eb
- Department of Motion and Exercise Science, University of Stuttgart, Stuttgart, Germany
| | - David S. Ryan
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Vancouver, BC, Canada
| | - James M. Wakeling
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Vancouver, BC, Canada
| | - Norman Stutzig
- Department of Motion and Exercise Science, University of Stuttgart, Stuttgart, Germany
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15
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Siebert T, Stutzig N, Rode C. A hill-type muscle model expansion accounting for effects of varying transverse muscle load. J Biomech 2018; 66:57-62. [PMID: 29154088 DOI: 10.1016/j.jbiomech.2017.10.043] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2017] [Revised: 10/21/2017] [Accepted: 10/28/2017] [Indexed: 11/29/2022]
Abstract
Recent studies demonstrated that uniaxial transverse loading (FG) of a rat gastrocnemius medialis muscle resulted in a considerable reduction of maximum isometric muscle force (ΔFim). A hill-type muscle model assuming an identical gearing G between both ΔFim and FG as well as lifting height of the load (Δh) and longitudinal muscle shortening (ΔlCC) reproduced experimental data for a single load. Here we tested if this model is able to reproduce experimental changes in ΔFim and Δh for increasing transverse loads (0.64 N, 1.13 N, 1.62 N, 2.11 N, 2.60 N). Three different gearing ratios were tested: (I) constant Gc representing the idea of a muscle specific gearing parameter (e.g. predefined by the muscle geometry), (II) Gexp determined in experiments with varying transverse load, and (III) Gf that reproduced experimental ΔFim for each transverse load. Simulations using Gc overestimated ΔFim (up to 59%) and Δh (up to 136%) for increasing load. Although the model assumption (equal G for forces and length changes) held for the three lower loads using Gexp and Gf, simulations resulted in underestimation of ΔFim by 38% and overestimation of Δh by 58% for the largest load, respectively. To simultaneously reproduce experimental ΔFim and Δh for the two larger loads, it was necessary to reduce Fim by 1.9% and 4.6%, respectively. The model seems applicable to account for effects of muscle deformation within a range of transverse loading when using a linear load-dependent function for G.
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Affiliation(s)
- Tobias Siebert
- Institute of Sport and Motion Science, University of Stuttgart, Stuttgart, Germany.
| | - Norman Stutzig
- Institute of Sport and Motion Science, University of Stuttgart, Stuttgart, Germany
| | - Christian Rode
- Department of Motion Science, Friedrich-Schiller University Jena, Jena, Germany
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16
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von Laßberg C, Schneid JA, Graf D, Finger F, Rapp W, Stutzig N. Longitudinal sequencing in intramuscular coordination: A new hypothesis of dynamic functions in the human rectus femoris muscle. PLoS One 2017; 12:e0183204. [PMID: 28817715 PMCID: PMC5560678 DOI: 10.1371/journal.pone.0183204] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2016] [Accepted: 07/31/2017] [Indexed: 11/18/2022] Open
Abstract
The punctum fixum-punctum mobile model has been introduced in previous publications. It describes general principles of intersegmental neuromuscular succession patterns to most efficiently generate specific movement intentions. The general hypothesis of this study is that these principles—if they really do indicate a fundamental basis for efficient movement generation—should also be found in intramuscular coordination and should be indicated by “longitudinal sequencing” between fibers according to the principles of the punctum fixum-punctum mobile model. Based on this general hypothesis an operationalized model was developed for the rectus femoris muscle (RF), to exemplarily scrutinize this hypothesis for the RF. Electromyography was performed for 14 healthy male participants by using two intramuscular fine wire electrodes in the RF (placed proximal and distal), three surface electrodes over the RF (placed proximal, middle, and distal), and two surface electrodes over the antagonists (m. biceps femoris and m. semitendinosus). Three movement tasks were measured: kicking movements; deceleration after sprints; and passively induced backward accelerations of the leg. The results suggest that proximal fibers can be activated independently from distal fibers within the RF. Further, it was shown that the hypothesized function of “intramuscular longitudinal sequencing” does exist during dynamic movements. According to the punctum fixum-punctum mobile model, the activation succession between fibers changes direction (from proximal to distal or inversely) depending on the intentional context. Thus, the results seem to support the general hypothesis for the RF and could be principally in line with the operationalized “inter-fiber to tendon interaction model”.
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Affiliation(s)
- Christoph von Laßberg
- Department of Sports Medicine, Medical Clinic, University of Tübingen, Tübingen, Germany
- * E-mail:
| | - Julia A. Schneid
- Institute of Sports Science, University of Tübingen, Tübingen, Germany
| | - Dominik Graf
- Institute of Sports Science, University of Tübingen, Tübingen, Germany
| | - Felix Finger
- Institute of Sports Science, University of Tübingen, Tübingen, Germany
| | - Walter Rapp
- Institute of Sports and Sport Science, University of Freiburg, Freiburg, Germany
| | - Norman Stutzig
- Department of Sport and Motion Science, University of Stuttgart, Stuttgart, Germany
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17
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Moll K, Gussew A, Hein C, Stutzig N, Reichenbach JR. Combined spiroergometry and 31 P-MRS of human calf muscle during high-intensity exercise. NMR Biomed 2017; 30:e3723. [PMID: 28340292 DOI: 10.1002/nbm.3723] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2016] [Revised: 02/07/2017] [Accepted: 02/08/2017] [Indexed: 06/06/2023]
Abstract
Simultaneous measurements of pulmonary oxygen consumption (VO2 ), carbon dioxide exhalation (VCO2 ) and phosphorus magnetic resonance spectroscopy (31 P-MRS) are valuable in physiological studies to evaluate muscle metabolism during specific loads. Therefore, the aim of this study was to adapt a commercially available spirometric device to enable measurements of VO2 and VCO2 whilst simultaneously performing 31 P-MRS at 3 T. Volunteers performed intense plantar flexion of their right calf muscle inside the MR scanner against a pneumatic MR-compatible pedal ergometer. The use of a non-magnetic pneumotachograph and extension of the sampling line from 3 m to 5 m to place the spirometric device outside the MR scanner room did not affect adversely the measurements of VO2 and VCO2 . Response and delay times increased, on average, by at most 0.05 s and 0.79 s, respectively. Overall, we were able to demonstrate a feasible ventilation response (VO2 = 1.05 ± 0.31 L/min; VCO2 = 1.11 ± 0.33 L/min) during the exercise of a single calf muscle, as well as a good correlation between local energy metabolism and muscular acidification (τPCr fast and pH; R2 = 0.73, p < 0.005) and global respiration (τPCr fast and VO2 ; R2 = 0.55, p = 0.01). This provides improved insights into aerobic and anaerobic energy supply during strong muscular performances.
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Affiliation(s)
- K Moll
- Medical Physics Group, Institute of Diagnostic and Interventional Radiology, Jena University Hospital, Friedrich Schiller University Jena, Jena, Germany
| | - A Gussew
- Medical Physics Group, Institute of Diagnostic and Interventional Radiology, Jena University Hospital, Friedrich Schiller University Jena, Jena, Germany
| | - C Hein
- Ganshorn Medizin Electronic GmbH, Niederlauer, Germany
| | - N Stutzig
- Exercise Science, Institute of Sport and Movement Science, University of Stuttgart, Stuttgart, Germany
| | - J R Reichenbach
- Medical Physics Group, Institute of Diagnostic and Interventional Radiology, Jena University Hospital, Friedrich Schiller University Jena, Jena, Germany
- Michael Stifel Center for Data-Driven and Simulation Science Jena, Friedrich Schiller University Jena, Jena, Germany
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18
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Stutzig N, Zimmermann B, Büsch D, Siebert T. Analysis of game variables to predict scoring and performance levels in elite men’s volleyball. INT J PERF ANAL SPOR 2017. [DOI: 10.1080/24748668.2015.11868833] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Affiliation(s)
- Norman Stutzig
- Affiliation: Institute of Sport-and Movement Science, University of Stuttgart postal Address: Allmandring 28, 70569 Stuttgart
| | - Bernd Zimmermann
- Affiliation: Department of Technique-Tactics, Institute of Applied Exercise Science postal Address: Marschner Straße 29, 04109 Leipzig
| | - Dirk Büsch
- Affiliation: Department of Technique-Tactics, Institute of Applied Exercise Science postal Address: Marschner Straße 29, 04109 Leipzig
| | - Tobias Siebert
- Affiliation: Institute of Sport-and Movement Science, University of Stuttgart postal Address: Allmandring 28, 70569 Stuttgart
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19
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Stutzig N, Rzanny R, Moll K, Gussew A, Reichenbach JR, Siebert T. Interpretation of pH-heterogeneity in human muscle induced by neuromuscular electrical stimulation. Magn Reson Med 2016; 77:466. [PMID: 27928835 DOI: 10.1002/mrm.26568] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2016] [Accepted: 11/14/2016] [Indexed: 11/11/2022]
Affiliation(s)
- Norman Stutzig
- Exercise Science, Institute of Sport and Movement Science, University of Stuttgart, Stuttgart, Germany
| | - Reinhard Rzanny
- Medical Physics Group, Institute of Diagnostic and Interventional Radiology, University Hospital Jena, Jena, Germany
| | - Kevin Moll
- Medical Physics Group, Institute of Diagnostic and Interventional Radiology, University Hospital Jena, Jena, Germany
| | - Alexander Gussew
- Medical Physics Group, Institute of Diagnostic and Interventional Radiology, University Hospital Jena, Jena, Germany
| | - Jürgen R Reichenbach
- Medical Physics Group, Institute of Diagnostic and Interventional Radiology, University Hospital Jena, Jena, Germany
| | - Tobias Siebert
- Exercise Science, Institute of Sport and Movement Science, University of Stuttgart, Stuttgart, Germany
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20
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Rzanny R, Stutzig N, Hiepe P, Gussew A, Thorhauer HA, Reichenbach JR. The reproducibility of different metabolic markers for muscle fiber type distributions investigated by functional 31P-MRS during dynamic exercise. Z Med Phys 2016; 26:323-338. [PMID: 27527556 DOI: 10.1016/j.zemedi.2016.06.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2015] [Revised: 06/20/2016] [Accepted: 06/23/2016] [Indexed: 02/06/2023]
Abstract
PURPOSE The objective of the study was to investigate the reproducibility of exercise induced pH-heterogeneity by splitting of the inorganic phosphate (Pi) signal in the corresponding 31P-MRS spectra and to compare results of this approach with other fiber-type related markers, like phosphocreatine/adenosine triphosphate (PCr/ATP) ratio, and PCr-recovery parameters. MATERIAL AND METHODS Subjects (N=3) with different sportive background were tested in 10 test sessions separated by at least 3 days. A MR-compatible pedal ergometer was used to perform the exercise and to induce a pH-based splitting of the Pi-signal in 31P-MR spectra of the medial gastrocnemius muscle. The PCr recovery was analyzed using a non-negative least square algorithm (NNLS) and multi-exponential regression analysis to estimate the number of non-exponential components as well as their amplitude and time constant. The reproducibility of the estimated metabolic marker and the resulting fiber-type distributions between the 10 test sessions were compared. RESULTS The reproducibility (standard deviation between measurements) based on (1) Pi components varied from 2% to 4%, (2) PCr recovery time components varied from 10% to 12% and (3) phosphate concentrations at rest varied from 8% to 11% between test sessions. Due to the sportive activity differences between the 3 subjects were expected in view of fiber type distribution. All estimated markers indicate the highest type I percentage for volunteer 3 medium for volunteer 2 and the lowest for volunteer 1. CONCLUSIONS The relative high reproducibility of pH dependent Pi components during exercise indicates a high potential of this method to estimate muscle fiber-type distributions in vivo. To make this method usable not only to detect differences in muscle fiber distributions but also to determine individual fiber-type volume contents it is therefore recommended to validate this marker by histological methods and to reveal the effects of muscle fiber recruitments and fiber-type specific Pi concentrations on the intensity ratios between the splitted Pi-components.
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Affiliation(s)
- Reinhard Rzanny
- Medical Physics Group, Institute of Diagnostic and Interventional Radiology, University Hospital Jena, Germany.
| | - Norman Stutzig
- Exercise Science, Institute of Sport and Movement Science, University of Stuttgart, Germany
| | - Patrick Hiepe
- Medical Physics Group, Institute of Diagnostic and Interventional Radiology, University Hospital Jena, Germany
| | - Alexander Gussew
- Medical Physics Group, Institute of Diagnostic and Interventional Radiology, University Hospital Jena, Germany
| | | | - Jürgen R Reichenbach
- Medical Physics Group, Institute of Diagnostic and Interventional Radiology, University Hospital Jena, Germany
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21
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Stutzig N, Rzanny R, Moll K, Gussew A, Reichenbach JR, Siebert T. The pH heterogeneity in human calf muscle during neuromuscular electrical stimulation. Magn Reson Med 2016; 77:2097-2106. [PMID: 27436629 DOI: 10.1002/mrm.26329] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2016] [Revised: 06/02/2016] [Accepted: 06/12/2016] [Indexed: 12/30/2022]
Abstract
PURPOSE The aim of the study was to examine pH heterogeneity during fatigue induced by neuromuscular electrical stimulation (NMES) using phosphorus magnetic resonance spectroscopy (31 P-MRS). It is hypothesized that three pH components would occur in the 31 P-MRS during fatigue, representing three fiber types. METHODS The medial gastrocnemius of eight subjects was stimulated within a 3-Tesla whole body MRI scanner. The maximal force during stimulation (Fstim ) was examined by a pressure sensor. Phosphocreatine (PCr), adenosintriphosphate, inorganic phosphate (Pi), and the corresponding pH were estimated by a nonvolume-selective 31 P-MRS using a small loop coil at rest and during fatigue. RESULTS During fatigue, Fstim and PCr decreased to 27% and 33% of their initial levels, respectively. In all cases, the Pi peak increased when NMES was started and split into three different peaks. Based on the single Pi peaks during fatigue, an alkaline (6.76 ± 0.08), a medium (6.40 ± 0.06), and an acidic (6.09 ± 0.05) pH component were observed compared to the pH (7.02 ± 0.02) at rest. CONCLUSION It is suggested that NMES is able to induce pH heterogeneity in the medial gastrocnemius, and that the single Pi peaks represent the different muscle fiber types of the skeletal muscle. Magn Reson Med 77:2097-2106, 2017. © 2016 International Society for Magnetic Resonance in Medicine.
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Affiliation(s)
- Norman Stutzig
- Exercise Science, Institute of Sport and Movement Science, University of Stuttgart, Stuttgart, Germany
| | - Reinhard Rzanny
- Medical Physics Group, Institute of Diagnostic and Interventional Radiology, University Hospital Jena, Jena, Germany
| | - Kevin Moll
- Medical Physics Group, Institute of Diagnostic and Interventional Radiology, University Hospital Jena, Jena, Germany
| | - Alexander Gussew
- Medical Physics Group, Institute of Diagnostic and Interventional Radiology, University Hospital Jena, Jena, Germany
| | - Jürgen R Reichenbach
- Medical Physics Group, Institute of Diagnostic and Interventional Radiology, University Hospital Jena, Jena, Germany
| | - Tobias Siebert
- Exercise Science, Institute of Sport and Movement Science, University of Stuttgart, Stuttgart, Germany
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Siebert T, Rode C, Till O, Stutzig N, Blickhan R. Force reduction induced by unidirectional transversal muscle loading is independent of local pressure. J Biomech 2016; 49:1156-1161. [PMID: 26976226 DOI: 10.1016/j.jbiomech.2016.02.053] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2015] [Revised: 02/19/2016] [Accepted: 02/29/2016] [Indexed: 10/22/2022]
Abstract
Transversal unidirectional compression applied to muscles via external loading affects muscle contraction dynamics in the longitudinal direction. A recent study reported decreasing longitudinal muscle forces with increasing transversal load applied with a constant contact area (i.e., leading to a simultaneous increase in local pressure). To shed light on these results, we examine whether the decrease in longitudinal force depends on the load, the local pressure, or both. To this end, we perform isometric experiments on rat M. gastrocnemius medialis without and with transversal loading (i) changing the local pressure from 1.1-3.2Ncm(-2) (n=9) at a constant transversal load (1.62N) and (ii) increasing the transversal load (1.15-3.45N) at a constant local pressure of 2.3Ncm(-2) (n=7). While we did not note changes in the decrease in longitudinal muscle force in the first experiment, the second experiment resulted in an almost-linear reduction of longitudinal force between 7.5±0.6% and 14.1±1.7%. We conclude that the observed longitudinal force reduction is not induced by local effects such as malfunction of single muscle compartments, but that similar internal stress conditions and myofilament configurations occur when the local pressure changes given a constant load. The decreased longitudinal force may be explained by increased internal pressure and a deformed myofilament lattice that is likely associated with the decomposition of cross-bridge forces on the one hand and the inhibition of cross-bridges on the other hand.
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Affiliation(s)
- Tobias Siebert
- Institute of Sport and Motion Science, University of Stuttgart, Stuttgart, Germany.
| | - Christian Rode
- Department of Motion Science, Friedrich-Schiller University Jena, Jena, Germany
| | - Olaf Till
- Department of Motion Science, Friedrich-Schiller University Jena, Jena, Germany
| | - Norman Stutzig
- Institute of Sport and Motion Science, University of Stuttgart, Stuttgart, Germany
| | - Reinhard Blickhan
- Department of Motion Science, Friedrich-Schiller University Jena, Jena, Germany
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Abstract
The aim of the present study was to compare the H-reflex evoked at rest and at 20% maximal voluntary contraction (MVC) prior to and after fatiguing the lateral gastrocnemius (LG). The maximal H-reflex and M-wave were recorded in the LG, and soleus (SOL). Electrical evoked potentials were delivered to the posterior tibial nerve when muscles were inactivated and at 20% MVC. After fatigue, the Hmax /Mmax ratio of the fatigued LG was increased for both contraction levels (rest and 20% MVC) and remained unaltered for non-fatigued SOL. Before fatigue, the Hmax /Mmax ratio of SOL was enhanced at rest compared with the Hmax /Mmax ratio at 20% MVC. No differences were observed for LG. Fatigue of a single muscle leads to increased spinal reflex activity of the homonymous muscle. Contrary to previous recommendations in the literature, there appears to be no benefit with regard to the H-reflex amplitude in evoking electrical potentials during constant voluntary contractions at 20% MVC compared with inactivated muscles. The observed difference in SOL prior to fatigue was most likely due to hyperpolarization of the muscle fiber membrane.
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Affiliation(s)
- N Stutzig
- Department of Exercise Science, Institute of Sport- and Movement Science, University of Stuttgart, Stuttgart, Germany
| | - T Siebert
- Department of Exercise Science, Institute of Sport- and Movement Science, University of Stuttgart, Stuttgart, Germany
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Stutzig N, Siebert T. Reproducibility of electromyographic and mechanical parameters of the triceps surae during submaximal and maximal plantar flexions. Muscle Nerve 2016; 53:464-70. [PMID: 26173034 DOI: 10.1002/mus.24767] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/07/2015] [Indexed: 12/17/2022]
Abstract
INTRODUCTION Neuromuscular parameters must be reproducible to examine neuromuscular adaptations in interventional and clinical studies. The reproducibility of neuromuscular parameters for the soleus (SOL), lateral gastrocnemius (LG), and medial gastrocnemius (MG) was assessed over a period of 2 weeks. METHODS Thirteen subjects (27.4 years, 69.5 kg) were tested for numerous electromyographic (e.g., voluntary and electrical evoked EMG) and mechanical (e.g., voluntary activation level) parameters in 3 test sessions. RESULTS The majority of the data (28 of 34) revealed moderate and substantial reproducibility. Hmax20% /Mmax20% and Vsup /Msup were less reproducible in LG than in MG and SOL. Muscle activity and M-waves did not differ between muscles. The ICC for the mechanical data was >0.79. CONCLUSIONS The H-reflex during voluntary contraction of the LG should be considered with caution. Mechanical data on muscle activation level are reproducible. The reproducibility of neuromuscular parameters is sufficient for interventional studies.
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Affiliation(s)
- Norman Stutzig
- Institute of Sport and Movement Science, University of Stuttgart, Allmandring 28, 70569, Stuttgart, Germany
| | - Tobias Siebert
- Institute of Sport and Movement Science, University of Stuttgart, Allmandring 28, 70569, Stuttgart, Germany
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Siebert T, Leichsenring K, Rode C, Wick C, Stutzig N, Schubert H, Blickhan R, Böl M. Three-Dimensional Muscle Architecture and Comprehensive Dynamic Properties of Rabbit Gastrocnemius, Plantaris and Soleus: Input for Simulation Studies. PLoS One 2015; 10:e0130985. [PMID: 26114955 PMCID: PMC4482742 DOI: 10.1371/journal.pone.0130985] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2015] [Accepted: 05/26/2015] [Indexed: 11/19/2022] Open
Abstract
The vastly increasing number of neuro-muscular simulation studies (with increasing numbers of muscles used per simulation) is in sharp contrast to a narrow database of necessary muscle parameters. Simulation results depend heavily on rough parameter estimates often obtained by scaling of one muscle parameter set. However, in vivo muscles differ in their individual properties and architecture. Here we provide a comprehensive dataset of dynamic (n = 6 per muscle) and geometric (three-dimensional architecture, n = 3 per muscle) muscle properties of the rabbit calf muscles gastrocnemius, plantaris, and soleus. For completeness we provide the dynamic muscle properties for further important shank muscles (flexor digitorum longus, extensor digitorum longus, and tibialis anterior; n = 1 per muscle). Maximum shortening velocity (normalized to optimal fiber length) of the gastrocnemius is about twice that of soleus, while plantaris showed an intermediate value. The force-velocity relation is similar for gastrocnemius and plantaris but is much more bent for the soleus. Although the muscles vary greatly in their three-dimensional architecture their mean pennation angle and normalized force-length relationships are almost similar. Forces of the muscles were enhanced in the isometric phase following stretching and were depressed following shortening compared to the corresponding isometric forces. While the enhancement was independent of the ramp velocity, the depression was inversely related to the ramp velocity. The lowest effect strength for soleus supports the idea that these effects adapt to muscle function. The careful acquisition of typical dynamical parameters (e.g. force-length and force-velocity relations, force elongation relations of passive components), enhancement and depression effects, and 3D muscle architecture of calf muscles provides valuable comprehensive datasets for e.g. simulations with neuro-muscular models, development of more realistic muscle models, or simulation of muscle packages.
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Affiliation(s)
- Tobias Siebert
- Department of Sport and Motion Science, University of Stuttgart, Stuttgart, Germany
- * E-mail:
| | - Kay Leichsenring
- Department of Sport and Motion Science, University of Stuttgart, Stuttgart, Germany
| | - Christian Rode
- Institute of Motion Science, Friedrich-Schiller-University Jena, Jena, Germany
| | - Carolin Wick
- Institute of Motion Science, Friedrich-Schiller-University Jena, Jena, Germany
| | - Norman Stutzig
- Department of Sport and Motion Science, University of Stuttgart, Stuttgart, Germany
| | - Harald Schubert
- Institut für Versuchstierkunde und Tierschutz, Universitätsklinikum Jena, Jena, Germany
| | - Reinhard Blickhan
- Institute of Motion Science, Friedrich-Schiller-University Jena, Jena, Germany
| | - Markus Böl
- Institute of Solid Mechanics, Technical University at Braunschweig, Braunschweig, Germany
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Stutzig N, Siebert T. Influence of joint position on synergistic muscle activity after fatigue of a single muscle head. Muscle Nerve 2015; 51:259-67. [PMID: 24890377 DOI: 10.1002/mus.24305] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2014] [Revised: 05/21/2014] [Accepted: 05/29/2014] [Indexed: 11/11/2022]
Abstract
INTRODUCTION We investigated synergistic muscle activity after fatigue of a single muscle in different joint positions. METHODS Two experimental groups (n = 12 each) performed maximal voluntary contractions (MVCs) before and after fatiguing the gastrocnemius lateralis (GL), using neuromuscular electrical stimulation (NMES). Neuromuscular tests, including muscle activity during MVC, H-reflex, and twitch interpolation, were performed. One group completed the experiment in a knee-extended position with the second group in a knee-flexed position. RESULTS In the knee-flexed position, the muscle activity increased in non-stimulated synergistic muscles. In contrast, in the knee-extended position, muscle activity of the synergistic muscles remained unaltered. The MVC force remained unaltered in the flexed position and decreased in the extended position. CONCLUSIONS Synergistic muscles compensate for the fatigued muscle in the flexed position but not in the extended position. Compensation mechanisms seem to depend on joint position.
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Affiliation(s)
- Norman Stutzig
- Exercise Science, Institute of Sport and Movement Science, University of Stuttgart, Allmandring 28, 70569, Stuttgart, Germany; Exercise Science, Institute of Sport Science, Friedrich Schiller University Jena, Seidelstraße 20, 07749 Jena, Germany
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Siebert T, Till O, Stutzig N, Günther M, Blickhan R. Muscle force depends on the amount of transversal muscle loading. J Biomech 2014; 47:1822-8. [PMID: 24725439 DOI: 10.1016/j.jbiomech.2014.03.029] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2013] [Revised: 02/06/2014] [Accepted: 03/18/2014] [Indexed: 11/16/2022]
Abstract
Skeletal muscles are embedded in an environment of other muscles, connective tissue, and bones, which may transfer transversal forces to the muscle tissue, thereby compressing it. In a recent study we demonstrated that transversal loading of a muscle with 1.3Ncm(-2) reduces maximum isometric force (Fim) and rate of force development by approximately 5% and 25%, respectively. The aim of the present study was to examine the influence of increasing transversal muscle loading on contraction dynamics. Therefore, we performed isometric experiments on rat M. gastrocnemius medialis (n=9) without and with five different transversal loads corresponding to increasing pressures of 1.3Ncm(-2) to 5.3Ncm(-2) at the contact area between muscle and load. Muscle loading was induced by a custom-made plunger which was able to move in transversal direction. Increasing transversal muscle loading resulted in an almost linear decrease in muscle force from 4.8±1.8% to 12.8±2% Fim. Compared to an unloaded isometric contraction, rate of force development decreased from 20.2±4.0% at 1.3Ncm(-2) muscle loading to 34.6±5.7% at 5.3Ncm(-2). Experimental observation of the impact of transversal muscle loading on contraction dynamics may help to better understand muscle tissue properties. Moreover, applying transversal loads to muscles opens a window to analyze three-dimensional muscle force generation. Data presented in this study may be important to develop and validate muscle models which enable simulation of muscle contractions under compression and enlighten the mechanisms behind.
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Affiliation(s)
- Tobias Siebert
- Institute of Sport and Motion Science, University of Stuttgart, Allmandring 28, D-70569 Stuttgart, Germany.
| | - Olaf Till
- Institute of Motion Science, Friedrich-Schiller-University Jena, Jena, Germany
| | - Norman Stutzig
- Institute of Sport and Motion Science, University of Stuttgart, Allmandring 28, D-70569 Stuttgart, Germany
| | - Michael Günther
- Institute of Sport and Motion Science, University of Stuttgart, Allmandring 28, D-70569 Stuttgart, Germany
| | - Reinhard Blickhan
- Institute of Motion Science, Friedrich-Schiller-University Jena, Jena, Germany
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Stutzig N, Siebert T, Granacher U, Blickhan R. Alteration of synergistic muscle activity following neuromuscular electrical stimulation of one muscle. Brain Behav 2012; 2:640-6. [PMID: 23139909 PMCID: PMC3489816 DOI: 10.1002/brb3.87] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/16/2012] [Revised: 07/10/2012] [Accepted: 07/16/2012] [Indexed: 11/08/2022] Open
Abstract
The aim of the study was to determine muscle activation of the m. triceps surae during maximal voluntary contractions (MVCs) following neuromuscular electrical stimulation (NMES) of the m. gastrocnemius lateralis (GL). The participants (n = 10) performed three MVC during pretest, posttest, and recovery, respectively. Subsequent to the pretest, the GL was stimulated by NMES. During MVC, force and surface electromyography (EMG) of the GL, m. gastrocnemius medialis (GM), and m. soleus (SOL) were measured. NMES of GL induced no significant decline (3%) in force. EMG activity of the GL decreased significantly to 81% (P < 0.05), whereas EMG activity of the synergistic SOL increased to 112% (P < 0.01). The GM (103%, P = 1.00) remained unaltered. Decreased EMG activity in the GL was most likely caused by failure of the electrical propagation at its muscle fiber membrane. The decline of EMG activity in GL was compensated by increased EMG activity of SOL during MVC. It is suggested that these compensatory effects are caused by central contributions induced by NMES.
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Affiliation(s)
- Norman Stutzig
- Institute of Sportscience, Friedrich-Schiller-University Seidelstraße 20, 07749, Jena, Germany
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Voelzke M, Stutzig N, Thorhauer HA, Granacher U. Promoting lower extremity strength in elite volleyball players: effects of two combined training methods. J Sci Med Sport 2012; 15:457-62. [PMID: 22484082 DOI: 10.1016/j.jsams.2012.02.004] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2011] [Revised: 02/03/2012] [Accepted: 02/24/2012] [Indexed: 10/28/2022]
Abstract
OBJECTIVES To compare the impact of short term training with resistance plus plyometric training (RT+P) or electromyostimulation plus plyometric training (EMS+P) on explosive force production in elite volleyball players. DESIGN Sixteen elite volleyball players of the first German division participated in a training study. METHODS The participants were randomly assigned to either the RT+P training group (n=8) or the EMS+P training group (n=8). Both groups participated in a 5-week lower extremity exercise program. Pre and post tests included squat jumps (SJ), countermovement jumps (CMJ), and drop jumps (DJ) on a force plate. The three-step reach height (RH) was assessed using a custom-made vertec apparatus. Fifteen m straight and lateral sprint (S15s and S15l) were assessed using photoelectric cells with interims at 5m and 10 m. RESULTS RT+P training resulted in significant improvements in SJ (+2.3%) and RH (+0.4%) performance. The EMS+P training group showed significant increases in performance of CMJ (+3.8%), DJ (+6.4%), RH (+1.6%), S15l (-3.8%) and after 5m and 10 m of the S15s (-2.6%; -0.5%). The comparison of training-induced changes between the two intervention groups revealed significant differences for the SJ (p=0.023) in favor of RT+P and for the S15s after 5m (p=0.006) in favor of EMS+P. CONCLUSIONS The results indicate that RT+P training is effective in promoting jump performances and EMS+P training increases jump, speed and agility performances of elite volleyball players.
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Affiliation(s)
- Mathias Voelzke
- Institute of Sport Science, Friedrich-Schiller-University, Jena, Germany
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Rzanny R, Stutzig N, Gussew A, Kaiser WA, Thorhauer HA, Reichenbach JR. 31P-MR-spektroskopische Untersuchungen des Muskelstoffwechsels an Probanden mit unterschiedlicher Faserverteilung. ROFO-FORTSCHR RONTG 2009. [DOI: 10.1055/s-0029-1221748] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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