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Smith IC, Onasch F, Kryściak K, Celichowski J, Herzog W. Contractile history affects sag and boost properties of unfused tetanic contractions in human quadriceps muscles. Eur J Appl Physiol 2020; 121:645-658. [PMID: 33221935 DOI: 10.1007/s00421-020-04561-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Accepted: 11/11/2020] [Indexed: 10/22/2022]
Abstract
PURPOSE A period of extra-efficient force production ("boost") followed by a decline in force ("sag") is often observed at the onset of unfused tetanic contractions. We tested the hypothesis that in human muscle boost and sag are diminished in repeated contractions separated by short rest periods and are re-established or enhanced following long rest periods. METHODS Two sets of 3 unfused tetanic contractions were evoked in the right quadriceps muscle group of 29 participants via percutaneous stimulation of the femoral nerve. Contractions consisted of 20 pulses evoked at inter-pulse intervals of 1.25 × twitch time to peak torque. Contractions were evoked 5 s apart and sets were evoked 5 min apart. RESULTS The ratio of the angular impulse of pulses 1-10 to the angular impulse of pulses 11-20 was used as the boost indicator. By this metric, boost was higher (P < 0.05) in the first relative to the second and third contractions within a set, but did not differ between sets (Set 1: 1.31 ± 0.15, 1.18 ± 0.12, 1.14 ± 0.12 vs Set 2: 1.34 ± 0.17, 1.17 ± 0.13, 1.14 ± 0.13). Sag (the percent decline in torque within each contraction) was also higher (P < 0.05) in the first relative to the second and third contractions within a set, but did not differ between sets (Set 1: 40.8 ± 7.5%, 35.4 ± 6.8%, 33.2 ± 7.8% vs Set 2: 42.1 ± 8.0%, 35.5 ± 6.8%, 33.9 ± 7.2%). Participants' sex and resistance training background did not influence boost or sag. CONCLUSION Boost and sag are sensitive to contractile history in whole human quadriceps. Optimizing boost may have application in strength and power sports.
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Affiliation(s)
- Ian C Smith
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, 2500 University Drive NW Calgary, Alberta, T2N 1N4, Canada.
| | - Franziska Onasch
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, 2500 University Drive NW Calgary, Alberta, T2N 1N4, Canada
| | - Katarzyna Kryściak
- Department of Neurobiology, Poznan University of Physical Education, 27/39 Królowej Jadwigi Street, 61-871, Poznań, Poland
| | - Jan Celichowski
- Department of Neurobiology, Poznan University of Physical Education, 27/39 Królowej Jadwigi Street, 61-871, Poznań, Poland
| | - Walter Herzog
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, 2500 University Drive NW Calgary, Alberta, T2N 1N4, Canada.,Biomechanics Laboratory, School of Sports, Federal University of Santa Catarina, Florianopolis, SC, Brazil
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Ching TT, Chen YC, Li G, Liu J, Xu XZS, Hsu AL. Short-term enhancement of motor neuron synaptic exocytosis during early aging extends lifespan in Caenorhabditis elegans. Exp Biol Med (Maywood) 2020; 245:1552-1559. [PMID: 32854519 DOI: 10.1177/1535370220950639] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
IMPACT STATEMENT The functional decline of motor activity is a common feature in almost all aging animals that leads to frailty, loss of independence, injury, and even death in the elderly population. Thus, understanding the molecular mechanism that drives the initial stage of this functional decline and developing strategies to increase human healthspan and even lifespan by targeting this process would be of great interests to the field. In this study, we found that by precisely targeting the motor neurons to potentiate its synaptic releases either genetically or pharmacologically, we can not only delay the functional aging at NMJs but also slow the rate of aging at the organismal level. Most importantly, we have demonstrated that a critical window of time, that is the early stage of NMJs functional decline, is required for the beneficial effects. A short-term treatment within this time period is sufficient to extend the animals' lifespan.
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Affiliation(s)
- Tsui-Ting Ching
- Institute of Biopharmaceutical Sciences, National Yang Ming University, Taipei 112, Taiwan
| | - Yen-Chieh Chen
- Institute of Biopharmaceutical Sciences, National Yang Ming University, Taipei 112, Taiwan
| | - Guang Li
- Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA.,International Research Center for Sensory Biology and Technology of MOST, Key Laboratory of Molecular Biophysics of MOE, and College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China
| | - Jianfeng Liu
- International Research Center for Sensory Biology and Technology of MOST, Key Laboratory of Molecular Biophysics of MOE, and College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China
| | - X Z Shawn Xu
- Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA.,Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Ao-Lin Hsu
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI 48109, USA.,Institute of Biochemistry and Molecular Biology, National Yang Ming University, Taipei 112, Taiwan.,Department of Internal Medicine, Division of Geriatric and Palliative Medicine, University of Michigan, Ann Arbor, MI 48109, USA.,Research Center for Healthy Aging and Institute of New Drug Development, China Medical University, Taichung 404, Taiwan
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Smith IC, Adam H, Herzog W. A brief contraction has complex effects on summation of twitch pairs in human adductor pollicis. Exp Physiol 2020; 105:676-689. [PMID: 32052487 DOI: 10.1113/ep088401] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Accepted: 02/10/2020] [Indexed: 11/08/2022]
Abstract
NEW FINDINGS What is the central question of this study? How do contraction-induced reductions in twitch duration, without changes in twitch force, affect summation of twitch pairs into higher force contractions in skeletal muscle? What is the main finding and its importance? Abbreviating twitch duration with a brief contraction resulted in enhanced summation of fully fused twitch pairs, but impaired summation in partially fused twitch pairs even after accounting for the differences in relaxation of the first twitch. An inherent mechanism which enhances relaxation without sacrificing force generation in forceful contractions would benefit cyclic muscle activities, such as locomotion. ABSTRACT During electrically evoked contractions of skeletal muscle, the interplay between twitch duration and the time between electrical stimuli (inter-pulse interval, IPI) determines how effectively twitch forces summate into high force contractions. A brief muscle contraction can impair summation by abbreviating twitch duration, though it is not clear if these impairments occur at all physiologically relevant IPI. This study was designed to test how a brief contraction affects summation of nominally isometric twitch pairs with IPIs lasting 10-5000 ms. Left adductor pollicis muscles of human participants (n = 9) were electrically activated using stimulus pairs applied both before (Pre) and after (Post) a 10 Hz, 1.0 s contraction. Force-time records were mathematically separated into Pulse 1 (single twitch) and Pulse 2 (summated twitch) components. The ratio of Pulse 2 peak force to Pulse 1 peak force was used as our measure of summation effectiveness. Consistent with the observed decline of Pulse 1 duration at Post relative to Pre (4.7 ± 0.6%; P < 0.001; duration was defined as the time from stimulation to the time required for active force to decline by 50%), summation effectiveness was higher at Pre than at Post at IPIs of 100-333 ms. Summation effectiveness was not different between Pre and Post at IPIs of 50-83 ms or 500-5000 ms. Intriguingly, summation effectiveness was higher at Post than at Pre at IPIs of 10-25 ms. In summary, a brief contraction has complex effects on the relationship between inter-pulse interval and summation effectiveness. Future experiments are needed to reveal the mechanisms behind this novel observation.
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Affiliation(s)
- Ian C Smith
- Human Performance Lab, Faculty of Kinesiology, University of Calgary 2500 University Drive NW, Calgary, Alberta, Canada, T2N 1N4
| | - Helen Adam
- Human Performance Lab, Faculty of Kinesiology, University of Calgary 2500 University Drive NW, Calgary, Alberta, Canada, T2N 1N4
| | - Walter Herzog
- Human Performance Lab, Faculty of Kinesiology, University of Calgary 2500 University Drive NW, Calgary, Alberta, Canada, T2N 1N4
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Transitory force decrease following a sudden reduction in stimulation frequency in motor units of rat medial gastrocnemius. J Electromyogr Kinesiol 2019; 46:14-20. [PMID: 30878001 DOI: 10.1016/j.jelekin.2019.02.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Revised: 01/25/2019] [Accepted: 02/23/2019] [Indexed: 11/22/2022] Open
Abstract
Effects of a sudden decrease in the stimulation frequency for motor unit force were studied in rat medial gastrocnemius. For 161 functionally isolated single motor units of three types (S, FR, FF), unfused tetanic contractions were evoked by three-phase trains of stimuli (low-high-low frequency). The course of the tetanus at the onset of the third phase of the force recording was analyzed in tetani with variable fusion degree. For 78 units within the third phase of tetanus, a transitory force decrease to a level lower than in the first phase (identical frequency), was observed. This phenomenon was more frequent for fast fatigue resistant (65.9%) than for fast fatigable and slow motor units (27.1% and 35.5%, respectively). Moreover, the force decrease was strongest for fast resistant motor units (up to 36.5%) and when contractions evoked at variable frequencies of stimulation were compared, the highest amplitudes of the studied force decrease were noted for middle-fused tetani (0.50-0.90). A new phenomenon of transitory force decrease in tetanic contractions of motor units with a decrease in stimulation frequency was found. Most probably, the phenomenon is dependent on disturbances in the force transmission by collagen surrounding active muscles fibers.
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Abstract
PURPOSE We examined how muscle length and time between stimuli (inter-pulse interval, IPI) influence declines in force (sag) seen during unfused tetani in the human adductor pollicis muscle. METHODS A series of 16-pulse contractions were evoked with IPIs between 1 × and 5 × the twitch time to peak tension (TPT) at large (long muscle length) and small (short muscle length) thumb adduction angles. Unfused tetani were mathematically deconstructed into a series of overlapping twitch contractions to examine why sag exhibits length- and IPI-dependencies. RESULTS Across all IPIs tested, sag was 62% greater at short than long muscle length, and sag increased as IPI was increased at both muscle lengths. Force attributable to the second stimulus increased as IPI was decreased. Twitch force declined from maximal values across all IPI tested, with the greatest reductions seen at short muscle length and long IPI. At IPI below 2 × TPT, the twitch with highest force occurred earlier than the peak force of the corresponding unfused tetani. Contraction-induced declines in twitch duration (TPT + half relaxation time) were only observed at IPI longer than 1.75 × TPT, and were unaffected by muscle length. CONCLUSIONS Sag is an intrinsic feature of healthy human adductor pollicis muscle. The length-dependence of sag is related to greater diminution of twitch force at short relative to long muscle length. The dependence of sag on IPI is related to IPI-dependent changes in twitch duration and twitch force, and the timing of peak twitch force relative to the peak force of the associated unfused tetanus.
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Affiliation(s)
- Ian C Smith
- Human Performance Lab, Faculty of Kinesiology, University of Calgary, 2500 University Drive NW, Calgary, AB, T2N 1N4, Canada.
| | - Jahaan Ali
- Human Performance Lab, Faculty of Kinesiology, University of Calgary, 2500 University Drive NW, Calgary, AB, T2N 1N4, Canada
| | - Geoffrey A Power
- Human Health and Nutritional Sciences, College of Biological Sciences, University of Guelph, 50 Stone Rd E, Guelph, ON, N1G 2W1, Canada
| | - Walter Herzog
- Human Performance Lab, Faculty of Kinesiology, University of Calgary, 2500 University Drive NW, Calgary, AB, T2N 1N4, Canada
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A General Mathematical Algorithm for Predicting the Course of Unfused Tetanic Contractions of Motor Units in Rat Muscle. PLoS One 2016; 11:e0162385. [PMID: 27622581 PMCID: PMC5021327 DOI: 10.1371/journal.pone.0162385] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2016] [Accepted: 07/31/2016] [Indexed: 12/02/2022] Open
Abstract
An unfused tetanus of a motor unit (MU) evoked by a train of pulses at variable interpulse intervals is the sum of non-equal twitch-like responses to these stimuli. A tool for a precise prediction of these successive contractions for MUs of different physiological types with different contractile properties is crucial for modeling the whole muscle behavior during various types of activity. The aim of this paper is to develop such a general mathematical algorithm for the MUs of the medial gastrocnemius muscle of rats. For this purpose, tetanic curves recorded for 30 MUs (10 slow, 10 fast fatigue-resistant and 10 fast fatigable) were mathematically decomposed into twitch-like contractions. Each contraction was modeled by the previously proposed 6-parameter analytical function, and the analysis of these six parameters allowed us to develop a prediction algorithm based on the following input data: parameters of the initial twitch, the maximum force of a MU and the series of pulses. Linear relationship was found between the normalized amplitudes of the successive contractions and the remainder between the actual force levels at which the contraction started and the maximum tetanic force. The normalization was made according to the amplitude of the first decomposed twitch. However, the respective approximation lines had different specific angles with respect to the ordinate. These angles had different and non-overlapping ranges for slow and fast MUs. A sensitivity analysis concerning this slope was performed and the dependence between the angles and the maximal fused tetanic force normalized to the amplitude of the first contraction was approximated by a power function. The normalized MU contraction and half-relaxation times were approximated by linear functions depending on the normalized actual force levels at which each contraction starts. The normalization was made according to the contraction time of the first contraction. The actual force levels were calculated initially from the recorded tetanic curves and subsequently from the modeled curves obtained from the summation of all models of the preceding contractions (the so called “full prediction”). The preciseness of the prediction was verified by two coefficients estimating the error between the modeled and the experimentally recorded curves. The proposed approach was tested for 30 MUs from the database and for three additional MUs, not included in the initial set. It was concluded that this general algorithm can be successfully used for modeling of a unfused tetanus course of a single MU of fast and slow type.
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Kubasov IV, Arutyunyan RS, Matrosova EV. Transformation of individual contractile responses during tetanus in rat fast and slow skeletal muscles. J EVOL BIOCHEM PHYS+ 2016. [DOI: 10.1134/s0022093016010051] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Celichowski J, Raikova R, Aladjov H, Krutki P. Dynamic changes of twitchlike responses to successive stimuli studied by decomposition of motor unit tetanic contractions in rat medial gastrocnemius. J Neurophysiol 2014; 112:3116-24. [PMID: 25253476 DOI: 10.1152/jn.00895.2013] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Unfused tetanic contractions evoked by trains of stimuli at variable interpulse intervals (IPIs) were recorded for 10 fast fatigable (FF), 10 fast resistant (FR), and 10 slow (S) motor units (MUs) and subsequently decomposed with a mathematical algorithm into trains of twitch-shape responses to successive stimuli. The mean stimulation frequencies were matched for each MU to evoke tetani of similar fusion degrees, whereas the variability range of IPIs was in each case 50-150% of the mean IPI. Force and time parameters of decomposed twitches were analyzed and related to the first response. Considerable variability of the analyzed twitch parameters was observed in each MU, although the largest range of variability occurred in slow MUs. In general, the decomposed twitch responses had longer duration and higher force than single-twitch contractions, although for nine FF and six FR MUs some of the decomposed responses were slightly weaker (but not faster) than the first twitches of these MUs. Comparison of the strongest decomposed twitch to the first decomposed twitch revealed ratios of forces up to 2.35, 3.33, and 6.89 for FF, FR, and S MUs and ratios of force-time areas up to 3.54, 4.67, and 14.26 for FF, FR, and S MUs, whereas for the contraction times the ratios of the longest decomposed twitch to the first twitch amounted to 2.46, 2.07, and 3.52 for FF, FR, and S MUs, respectively. The results indicate that contractile responses to successive action potentials are considerably variable, especially for slow MUs.
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Affiliation(s)
- Jan Celichowski
- Department of Neurobiology, University School of Physical Education, Poznań, Poland; and
| | - Rositsa Raikova
- Department of Neurobiology, University School of Physical Education, Poznań, Poland; and Institute of Biophysics and Biomedical Engineering, Bulgarian Academy of Sciences, Sofia, Bulgaria
| | - Hristo Aladjov
- Institute of Biophysics and Biomedical Engineering, Bulgarian Academy of Sciences, Sofia, Bulgaria
| | - Piotr Krutki
- Department of Neurobiology, University School of Physical Education, Poznań, Poland; and
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MacIntosh BR, Glumpak JJ, Macnaughton MB, Rassier DE. Pattern of summation with fatigue and inhibition of calcium release in rat muscle. Muscle Nerve 2011; 44:410-7. [DOI: 10.1002/mus.22073] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Celichowski J, Dobrzyńska Z, Łochyński D, Krutki P. The tetanic depression in fast motor units of mammalian skeletal muscle can be evoked by lengthening of one initial interpulse interval. Exp Brain Res 2011; 214:19-26. [PMID: 21800254 PMCID: PMC3170117 DOI: 10.1007/s00221-011-2801-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2011] [Accepted: 07/12/2011] [Indexed: 11/28/2022]
Abstract
A lower than expected tetanic force (the tetanic depression) is regularly observed in fast motor units (MUs) when a higher stimulation frequency immediately follows a lower one. The aim of the present study was to determine whether prolongation of only the first interpulse interval (IPI) resulted in tetanic depression. The experiments were carried out on fast MUs of the medial gastrocnemius muscle in cats and rats. The tetanic depression was measured in each case as the force decrease of a tetanus with one IPI prolonged in relation to the tetanic force at the respective constant stimulation frequency. Force depression was observed in all cases studied and was considerably greater in cats. For cats, the mean values of force depression amounted to 28.64% for FR and 10.86% for FF MUs whereas for rats 9.30 and 7.21% for FR and FF motor units, respectively. Since the phenomenon of tetanic depression in mammalian muscle is commonly observed even after a change in only the initial interpulse interval within a stimulation pattern, it can effectively influence processes of force regulation during voluntary activity of a muscle, when motoneurones progressively increase the firing rate.
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Affiliation(s)
- J Celichowski
- Department of Neurobiology, University School of Physical Education, 55 Grunwaldzka St., 60-352 Poznan, Poland.
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Ogneva IV, Altaeva EG. Effects of nifedipine on the mechanical properties of sarcolemma and modulation of dynamics of the increase in the basal calcium level in fibers of rat soleus muscle under short-term hypogravity conditions. Biophysics (Nagoya-shi) 2010. [DOI: 10.1134/s0006350910050222] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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Experimentally verified mathematical approach for the prediction of force developed by motor units at variable frequency stimulation patterns. J Biomech 2010; 43:1546-52. [PMID: 20185140 DOI: 10.1016/j.jbiomech.2010.01.034] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2009] [Revised: 12/21/2009] [Accepted: 01/06/2010] [Indexed: 11/24/2022]
Abstract
During normal daily activity, muscle motor units (MUs) develop unfused tetanic contractions evoked by trains of motoneuronal firings at variable interpulse intervals (IPIs). The mechanical responses of a MU to successive impulses are not identical. The aim of this study was to develop a mathematical approach for the prediction of each response within the tetanus as well as the tetanic force itself. Experimental unfused tetani of fast and slow rat MUs, evoked by trains of stimuli at variable IPIs, were decomposed into series of twitch-shaped responses to successive stimuli using a previously described algorithm. The relationships between the parameters of the modeled twitches and the tetanic force level at which the next response begins were examined and regression equations were derived. Using these equations, profiles of force for the same and different stimulation patterns were mathematically predicted by summating modeled twitches. For comparison, force predictions were made by the summation of twitches equal to the first one. The recorded and the predicted tetanic forces were compared. The results revealed that it is possible to predict tetanic force with high accuracy by using regression equations. The force predicted in this way was much closer to the experimental record than the force obtained by the summation of equal twitches, especially for slow MUs. These findings are likely to have an impact on the development of realistic muscle models composed of MUs, and will assist our understanding of the significance of the neuronal code in motor control and the role of biophysical processes during MU contractions.
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Marino BDV, Stethem KJ. Cells to society: lactate and neuromuscular incapacitation devices. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2009; 2009:7052-6. [PMID: 19964199 DOI: 10.1109/iembs.2009.5333374] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Devices employed in electrical policing rely on fundamental responses of nerve and muscle to supraphysiologic current to quell disruptive behavior. Whilst widely deployed the use of neuromuscular incapacitation (NMI) remains controversial, in part, due to gaps in understanding of the underlying mechanisms related to injury. NMI device manufacturers are thus constrained by empirical evidence for safety and effectiveness for a specific device design. Here we examine published data for several NMI devices considering ex vivo signal characteristics and in vivo responses in relation to effectiveness and injury. The sensitivity of lactate production to NMI device signal frequency (Hz) and macro-dosimetry is explored as a primary device design factor in NMI modes of injury. The non-lethal approach to policing regardless of technology will result in fatalities due to compromised health and substance abuse status unknowable at the time of NMI application. Thus, research to establish a science-based understanding of NMI injury mechanisms, particularly for lactate production and limitations of deployment, are essential for social acceptance and improved NMI device design.
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Model-generated decomposition of unfused tetani of motor units evoked by random stimulation. J Biomech 2008; 41:3448-54. [PMID: 18990394 DOI: 10.1016/j.jbiomech.2008.09.013] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2008] [Revised: 09/05/2008] [Accepted: 09/08/2008] [Indexed: 11/20/2022]
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