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Bright TE, Handford MJ, Mundy P, Lake J, Theis N, Hughes JD. Building for the Future: A Systematic Review of the Effects of Eccentric Resistance Training on Measures of Physical Performance in Youth Athletes. Sports Med 2023; 53:1219-1254. [PMID: 37097414 PMCID: PMC10185653 DOI: 10.1007/s40279-023-01843-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/17/2023] [Indexed: 04/26/2023]
Abstract
BACKGROUND Eccentric resistance training is recognised as an effective stimulus for enhancing measures of muscular strength and power in adult populations; however, its value in youth athletes is currently not well understood. OBJECTIVE The aim of this systematic review was to critically appraise the effects of eccentric resistance training on measures of physical performance (i.e. muscular strength, jump, sprint and change of direction) in youth athletes 18 years of age and under. METHODS Original journal articles published between 1950 and June 2022 were retrieved from electronic search engines of PubMed, SPORTDiscus and Google Scholar's advanced search option. Full journal articles investigating the acute and chronic effects of eccentric resistance training on measures of physical performance in youth athletes (i.e. a person 18 years of age or under who competes in sport) were included. The methodological quality and bias of each study were assessed prior to data extraction using a modified Downs and Black checklist. RESULTS The search yielded 749 studies, of which 436 were duplicates. Three-hundred studies were excluded based upon title and abstract review and a further 5 studies were removed following the modified Downs and Black checklist. An additional 14 studies were identified during backward screening. Accordingly, 22 studies were included in our systematic review. The Nordic hamstring exercise and flywheel inertial training were the most frequently used eccentric resistance training methods in youth athletes. Improvements in physical performance following the Nordic hamstring exercise are dependent upon an increase in the breakpoint angle, rather than training volume (sets and repetitions), and are further elevated with the addition of hip extension exercises or high-speed running. A minimum of 3 familiarisation trials is necessary to elicit meaningful adaptations following flywheel inertial training. Furthermore, an emphasis should be placed upon decelerating the rotating flywheel during the final one to two thirds of the eccentric phase, rather than gradually throughout the entire eccentric phase. CONCLUSIONS The findings of this systematic review support the inclusion of eccentric resistance training in youth athletes to improve measures of muscular strength, jump, sprint and change of direction performance. The current eccentric resistance training methods are predominantly limited to the Nordic hamstring exercise and flywheel inertial training; however, the efficacy of accentuated eccentric loading to improve jump performance warrants attention in future investigations.
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Affiliation(s)
- Thomas E. Bright
- Cardiff School of Sport and Health Sciences, Cardiff Metropolitan University, Cardiff, UK
- School of Sport and Exercise, University of Gloucestershire, Gloucester, UK
- School of Sport, Health and Wellbeing, Plymouth Marjon University, Derriford Rd, Plymouth, PL6 8BH UK
| | - Matthew J. Handford
- Cardiff School of Sport and Health Sciences, Cardiff Metropolitan University, Cardiff, UK
- School of Sport and Exercise, University of Gloucestershire, Gloucester, UK
| | | | - Jason Lake
- Department of Sport and Exercise Sciences, Chichester University, Chichester, UK
- School of Medical and Health Sciences, Edith Cowan University, Joondalup, WA Australia
| | - Nicola Theis
- School of Sport and Exercise, University of Gloucestershire, Gloucester, UK
| | - Jonathan D. Hughes
- Cardiff School of Sport and Health Sciences, Cardiff Metropolitan University, Cardiff, UK
- School of Sport and Exercise, University of Gloucestershire, Gloucester, UK
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Lulic-Kuryllo T, Greig Inglis J. Sex differences in motor unit behaviour: A review. J Electromyogr Kinesiol 2022; 66:102689. [DOI: 10.1016/j.jelekin.2022.102689] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Revised: 07/28/2022] [Accepted: 07/29/2022] [Indexed: 10/15/2022] Open
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Green LA, McGuire J, Gabriel DA. Effects of the Proprioceptive Neuromuscular Facilitation Contraction Sequence on Motor Skill Learning-Related Increases in the Maximal Rate of Wrist Flexion Torque Development. Front Hum Neurosci 2021; 15:764660. [PMID: 34803640 PMCID: PMC8595484 DOI: 10.3389/fnhum.2021.764660] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Accepted: 10/13/2021] [Indexed: 11/30/2022] Open
Abstract
Background: The proprioceptive neuromuscular facilitation (PNF) reciprocal contraction pattern has the potential to increase the maximum rate of torque development. However, it is a more complex resistive exercise task and may interfere with improvements in the maximum rate of torque development due to motor skill learning, as observed for unidirectional contractions. The purpose of this study was to examine the cost-benefit of using the PNF exercise technique to increase the maximum rate of torque development. Methods: Twenty-six participants completed isometric maximal extension-to-flexion (experimental PNF group) or flexion-only (control group) contractions at the wrist. Ten of the assigned contractions were performed on each of three sessions separated by 48-h for skill acquisition. Retention was assessed with 5 contractions performed 2-weeks after acquisition. Torque and surface electromyographic (sEMG) activity were analyzed for evidence of facilitated contractions between groups, as well as alterations in muscle coordination assessed across test sessions. The criterion measures were: mean maximal isometric wrist flexion toque; the maximal rate of torque development (dτ/dtmax); root-mean-square error (RMSE) variability of the rate of torque versus torque phase-plane; the rate of wrist flexion muscle activation (Q30); a coactivation ratio for wrist flexor and extensor sEMG activity; and wrist flexor electromechanical delay (EMD). Results: There were no significant differences between groups with respect to maximal wrist flexion torque, dτ/dtmax or RMSE variability of torque trajectories. Both groups exhibited a progressive increase in maximal strength (+23.35% p < 0.01, η2 = 0.655) and in dτ/dtmax (+19.84% p = 0.08, η2 = 0.150) from the start of acquisition to retention. RMSE was lowest after a 2-week rest interval (−18.2% p = 0.04, η2 = 0.198). There were no significant differences between groups in the rate of muscle activation or the coactivation ratio. There was a reduction in coactivation that was retained after a 2-week rest interval (−32.60%, p = 0.02, η2 = 0.266). Alternatively, EMD was significantly greater in the experimental group (Δ 77.43%, p < 0.01, η2 = 0.809) across all sessions. However, both groups had a similar pattern of improvement to the third consecutive day of testing (−16.82%, p = 0.049, η2 = 0.189), but returned close to baseline value after the 2-week rest interval. Discussion: The wrist extension-to-flexion contraction pattern did not result in a greater maximal rate of torque development than simple contractions of the wrist flexors. There was no difference between groups with respect to motor skill learning. The main adaptation in neuromotor control was a decrease in coactivation, not the maximal rate of muscle activation.
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Affiliation(s)
- Lara A Green
- Electromyographic Kinesiology Laboratory, Faculty of Applied Health Sciences, Brock University, St. Catharines, ON, Canada.,Exercise Neuroscience Laboratory, Department of Kinesiology, Wilfrid Laurier University, Waterloo, ON, Canada
| | - Jessica McGuire
- Electromyographic Kinesiology Laboratory, Faculty of Applied Health Sciences, Brock University, St. Catharines, ON, Canada
| | - David A Gabriel
- Electromyographic Kinesiology Laboratory, Faculty of Applied Health Sciences, Brock University, St. Catharines, ON, Canada
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Portela MA, Sánchez-Romero JI, Pérez VZ, Betancur MJ. Estimación de par basada en electromiografía de superficie: potencial herramienta para la rehabilitación de rodilla. REVISTA DE LA FACULTAD DE MEDICINA 2020. [DOI: 10.15446/revfacmed.v68n3.75214] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Introducción. Múltiples estudios de procesamiento de señales han reportado la aplicación de las señales de electromiografía de superficie (sEMG) en robótica y en procesos de rehabilitación motora.Objetivo. Realizar una revisión de la literatura sobre el uso de señales de sEMG como alternativa para la estimación del par de rodilla con el fin de medir objetivamente el progreso de los pacientes en las diferentes etapas de rehabilitación de lesiones de rodilla.Materiales y métodos. Se realizó una revisión de la literatura publicada entre 1986 y 2018, sin límites geográficos, en las bases de datos Engineering Village, IEEE Xplore, ScienceDirect, Web of Science, Scopus y PubMed mediante la combinación de 8 términos de búsqueda.Resultados. Al finalizar la búsqueda inicial se obtuvieron 355 registros. Luego de realizar la remoción de duplicados esta cifra descendió a 308, los cuales fueron analizados para determinar si cumplían con los criterios de inclusión. Finalmente se incluyeron 18 estudios que describen de forma comparativa cómo estimar el par a partir de señales de sEMG.Conclusiones. El uso de señales de sEMG para calcular el par en una articulación es una herramienta alternativa que permite al terapeuta acceder a parámetros cuantitativos y, de esta forma, valorar el progreso de los pacientes durante el proceso de rehabilitación de rodilla.
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Neuromuscular and Torque Kinetic Changes After 10 Months of Explosive Sport Training in Prepubertal Gymnasts. Pediatr Exerc Sci 2019; 31:77-84. [PMID: 30606075 DOI: 10.1123/pes.2018-0034] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
PURPOSE To determine neuromuscular and torque kinetic changes after 10 months of explosive sport training in the elbow of prepubertal gymnasts compared with untrained age-matched controls. METHODS In 15 young gymnasts (9.02 [0.41] y) and 15 age-matched untrained males (8.76 [0.51] y), the rate of torque development (RTD) using the Biodex System 4 and the coactivation index were evaluated using electromyography. Explosive strength variables were normalized to the peak torque. Measures were determined twice: before and after a 10-month period of gymnastic training. Covariation analysis was used to account for differences in baseline values between gymnasts and controls. RESULTS After 10 months of training, gymnasts demonstrated a significantly (P < .05) greater increase in normalized peak RTD values in elbow flexion compared with controls (7.76% vs 0.65%). Covariation analysis also revealed a significantly (P < .05) greater reduction in the coactivation index of elbow extension in the gymnasts (-7.81% [5.44%] points) compared with controls (-1.23% [6.32%] points). CONCLUSIONS Compared with physical development alone, 10 months of explosive-strength training of young gymnasts is sufficient to increase torque-normalized RTD in the elbow joint of prepubertal boys. The RTD changes the authors observed in antagonistic elbow functions vary among gymnasts due to the specific demands of gymnastic training.
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The Influence of Verbal Instruction on Measurement Reliability and Explosive Neuromuscular Performance of the Knee Extensors. J Hum Kinet 2018; 65:21-34. [PMID: 30687416 PMCID: PMC6341959 DOI: 10.2478/hukin-2018-0031] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
The current study aimed to examine the effect of verbal instruction on explosive force production and between-session measurement reliability during maximal voluntary contractions of knee extensors. Following familiarization, 20 healthy males performed 3 maximal contractions with a “hard-and-fast” instruction and 3 maximal contractions with a “fast” instruction during 2 test-retest sessions. Knee extension maximal voluntary force (Fmax) and the maximal rate of force development (RFDmax) were measured. Maximal electromechanical delay (EMDmax), and the maximal rate of muscle activation (RMAmax) of quadriceps muscles were determined. No significant effect of instruction was observed on Fmax (p > 0.05). The RFDmax and RMAmax were significantly higher with the “fast” compared to the “hard-and-fast” instruction (36.07%, ES = 1.99 and 37.24%, ES = 0.92, respectively), whereas EMDmax was significantly lower with the “fast” instruction compared to the “hard-and-fast” instruction (-3.79%, ES = - 0.29). No significant differences between test and retest measurements were found (p < 0.05). However, the reliability of the RFDmax was higher with the fast instruction compared to the hard-and-fast instruction (CV: 7.3 vs. 16.2%; ICC: 0.84 vs. 0.56). Besides, the RFDmax was associated with the RMAmax and EMDmax with a significant effect of instruction. Data showed that the instruction given prior contracting muscle affected explosive force production and associated neuromuscular variables. As a result, the “fast” instruction may be preferred in the assessment of explosive force capacity of skeletal muscle during maximal efforts.
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Jaafar H, Lajili H. Separate and combined effects of time of day and verbal instruction on knee extensor neuromuscular adjustments. Appl Physiol Nutr Metab 2018; 43:54-62. [DOI: 10.1139/apnm-2017-0343] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
We examined the effects of time of day and verbal instruction, separately and combined, on knee extensor neuromuscular adjustments, with special reference to rapid muscle force production capacity. Ten healthy male participants performed 4 experimental trials in counterbalanced order: morning “hard-and-fast” instruction, evening hard-and-fast instruction, morning “fast” instruction, and evening fast instruction. During each experimental trial, neuromuscular performance was assessed from the completion of 6 maximal isometric voluntary contractions (rest = 2 min) of the knee extensors with concomitant quadriceps surface electromyography recordings. For each contraction, we determined maximal voluntary force (Fmax), maximal rate of force development (RFDmax) and associated maximal electromechanical delay (EMDmax), and maximal rate of muscle activation (RMAmax). Globally, oral temperature (+2.2%), Fmax (+4.9%) and accompanying median frequency (+6.6%)/mean power frequency (+6.0%) as well as RFDmax (+13.5%) and RMAmax (+15.5%) were significantly higher in the evening than morning (p < 0.05). Conversely, evening in reference to morning values were lower for EMDmax (–4.3%, p < 0.05). Compared with a hard-and-fast instruction, RFDmax (+30.6%) and corresponding root mean square activity (+18.6%) were globally higher using a fast instruction (p < 0.05), irrespectively of the time of day. There was no significant interaction effect of time of day and verbal instruction on any parameter, except for EMDmax (p = 0.028). Despite diurnal variation in maximal or explosive force production of knee extensors and associated neuromuscular parameters, these adjustments occurred essentially independently of the verbal instruction provided.
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Affiliation(s)
- Hamdi Jaafar
- Institut du savoir Montfort – Recherche, Ottawa, 713 Chemin Montréal, Ottawa, ON K1K 0T2, Canada
- Faculty of Medicine, Biochemistry, Microbiology and Immunology Department, University of Ottawa, Ottawa, Ontario, Canada
| | - Hanene Lajili
- Centre de Rééducation et de Réadaptation Fonctionnelle La Châtaigneraie, Menucourt, France
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Rodríguez-Rosell D, Pareja-Blanco F, Aagaard P, González-Badillo JJ. Physiological and methodological aspects of rate of force development assessment in human skeletal muscle. Clin Physiol Funct Imaging 2017; 38:743-762. [DOI: 10.1111/cpf.12495] [Citation(s) in RCA: 76] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2017] [Accepted: 11/29/2017] [Indexed: 12/22/2022]
Affiliation(s)
- David Rodríguez-Rosell
- Centro de Investigación en Rendimiento Físico y Deportivo, Universidad Pablo de Olavide, Seville, Spain
| | - Fernando Pareja-Blanco
- Centro de Investigación en Rendimiento Físico y Deportivo, Universidad Pablo de Olavide, Seville, Spain
| | - Per Aagaard
- Department of Sports Science and Clinical Biomechanics, SDU Muscle Research Cluster (SMRC), University of Southern Denmark, Odense, Denmark
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Silva-Batista C, Corcos DM, Barroso R, David FJ, Kanegusuku H, Forjaz C, DE Mello MT, Roschel H, Tricoli V, Ugrinowitsch C. Instability Resistance Training Improves Neuromuscular Outcome in Parkinson's Disease. Med Sci Sports Exerc 2017; 49:652-660. [PMID: 27851668 DOI: 10.1249/mss.0000000000001159] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
PURPOSE This study compared the effects of resistance training (RT) and RT with instability (RTI) on neuromuscular and total training volume (TTV) outcomes obtained as part of the Instability Resistance Training Trial in Parkinson's disease. It also used a linear multiple regression (forward stepwise method) to identify the contribution of neuromuscular outcomes to previously published improvements in the timed-up-and-go test and the Unified Parkinson's Disease Rating Scale, motor subscale score. METHODS Thirty-nine patients with moderate to severe Parkinson's disease were randomly assigned to three groups: control (C), RT, and RTI. RT and RTI groups performed resistance exercises twice a week for 12 wk, and only the RTI group used unstable devices to perform resistance exercises. The following neuromuscular outcomes were assessed: quadriceps muscle cross-sectional area, root mean square and mean spike frequency of electromyographic signal, peak torque, rate of torque development, and half relaxation time of the knee extensors and plantarflexors during maximum ballistic voluntary isometric contractions. TTV was calculated for lower limb exercises. RESULTS From pre- to posttraining, RTI improved all of the neuromuscular outcomes (P < 0.05) except half relaxation time of the knee extensors (P = 0.068), despite the lower TTV than RT (P < 0.05). RTI was more effective than RT in increasing the root mean square values of vastus medialis, mean spike frequency of gastrocnemius medialis, and rate of torque development of plantarflexors (P < 0.05). Stepwise regression identified the changes in mean spike frequency of gastrocnemius medialis as the best predictor of improvements in timed-up-and-go test (R = 0.58, P = 0.002) and on-medication Unified Parkinson's Disease Rating Scale, motor subscale scores (R = 0.40, P = 0.020). CONCLUSION RTI optimizes neuromuscular adaptations, which partially explains mobility and motor sign improvements in patients with Parkinson's disease.
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Affiliation(s)
- Carla Silva-Batista
- 1Laboratory of Adaptations to Strength Training, School of Physical Education and Sport, University of São Paulo, São Paulo, BRAZIL; 2Department of Physical Therapy and Human Movement Sciences, Northwestern University, Chicago, IL; 3Department of Neurological Sciences, Rush University Medical Center, Chicago, IL; 4Department of Sport Sciences, State University of Campinas, Campinas, BRAZIL; 5Exercise Hemodynamic Laboratory, School of Physical Education and Sport, University of São Paulo at São Paulo, São Paulo, BRAZIL; and 6Center for Psychobiology and Exercise Studies, Federal University of São Paulo, São Paulo, BRAZIL
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Orizio C, Cogliati M, Bissolotti L, Gaffurini P, Marcolin G, Paoli A. Time color map and histogram of electromyography (EMG) sample amplitudes: possible tools for global electromyogram analysis by images. SPORT SCIENCES FOR HEALTH 2017. [DOI: 10.1007/s11332-017-0405-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Inglis JG, McIntosh K, Gabriel DA. Neural, biomechanical, and physiological factors involved in sex-related differences in the maximal rate of isometric torque development. Eur J Appl Physiol 2016; 117:17-26. [PMID: 27815705 PMCID: PMC5306324 DOI: 10.1007/s00421-016-3495-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2016] [Accepted: 10/21/2016] [Indexed: 11/17/2022]
Abstract
Objective Recent research has reported that lower maximal rate of torque development (dτ/dtmax) exhibited by females, relative to males, during knee extension can be accounted for by normalization to a maximal voluntary contraction (MVC); however, this was not seen in the upper limb. Purpose The aim of the current work was to examine the contribution of maximum strength (τmax), twitch contraction time (CT), muscle fiber condition velocity (MFCV), and rate of muscle activation (Q30) to sex-differences in the dτ/dtmax during maximal isometric dorsiflexion. Methods Thirty-eight participants (20 males; 18 females) performed both maximal voluntary and evoked isometric contractions of the tibialis anterior across 3 days. Ten maximal compound muscle action potentials were elicited and subsequently followed by three, 5-s contractions. From the recordings, MFCV, dτ/dtmax, τmax, CT, electromechanical delay (EMD), root-mean squared (RMS) amplitude, peak-to-peak voltage (Vpp), and Q30 were calculated. Results An ANCOVA showed that τmax accounted for all the sex-differences in dτ/dtmax (p = 0.96). There were no significant differences between groups with respect to MFCV, RMS amplitude, Vpp amplitude, or CT. However, there was a significant sex-difference in dτ/dtmax, τmax, and Q30. Females had longer evoked EMD times compared with males (15.69 ± 10.57 ms versus 9.95 ± 3.46 ms; p = 0.01), but the voluntary EMD times were not different. Conclusion The current research supports the work by Hannah et al. Exp Physiol 97:618–629, (2012) that normalization to MVC in the quadriceps is able to account for all sex-differences in rate of toque development in the lower limb.
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Affiliation(s)
- J Greig Inglis
- Electromyographic Kinesiology Laboratory, Faculty of Applied Health Sciences, Brock University, 1812 Sir Isaac Brock Way, St. Catharines, ON, L2S 3A1, Canada.
| | - Kyle McIntosh
- Electromyographic Kinesiology Laboratory, Faculty of Applied Health Sciences, Brock University, 1812 Sir Isaac Brock Way, St. Catharines, ON, L2S 3A1, Canada
| | - David A Gabriel
- Electromyographic Kinesiology Laboratory, Faculty of Applied Health Sciences, Brock University, 1812 Sir Isaac Brock Way, St. Catharines, ON, L2S 3A1, Canada
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Electromyogram features during linear torque decrement and their changes with fatigue. Eur J Appl Physiol 2014; 114:2105-17. [DOI: 10.1007/s00421-014-2928-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2013] [Accepted: 05/30/2014] [Indexed: 10/25/2022]
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Inglis JG, Vandenboom R, Gabriel DA. Sex-related differences in maximal rate of isometric torque development. J Electromyogr Kinesiol 2013; 23:1289-94. [DOI: 10.1016/j.jelekin.2013.09.005] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2012] [Revised: 09/04/2013] [Accepted: 09/20/2013] [Indexed: 11/29/2022] Open
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Dotan R, Mitchell CJ, Cohen R, Gabriel D, Klentrou P, Falk B. Explosive sport training and torque kinetics in children. Appl Physiol Nutr Metab 2013; 38:740-5. [PMID: 23980732 DOI: 10.1139/apnm-2012-0330] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A high rate of force development (RFD) is often more important than maximal force in daily and sports activities. In children, resistance training has been shown to increase maximal force. It is unclear whether, or to what extent, can children improve RFD and force kinetics. For this study, we compared strength and force kinetics of boy gymnasts with those of untrained boys and untrained men. Eight boy gymnasts (age, 9.5 ± 1.2 y), 20 untrained boys (age, 10.1 ± 1.3 y), and 20 untrained men (age, 22.9 ± 4.4 y) performed maximal, explosive, isometric elbow flexions (EF) and knee flexions (KF). Peak torque (maximal voluntary contraction (MVC)), elapsed times to 10%-100% MVC, peak rate of torque development (RTDpk), and other kinetics parameters were determined. When gymnasts were compared with untrained boys, size-normalized EF MVC was 11%-20% higher, RTDpk was 32% higher, and times to 30% and 80% MVC were 16% and 55% shorter, respectively (p < 0.05). No corresponding differences were observed in KF. Furthermore, although the normalized EF MVC was 28% lower in gymnasts than in men (p < 0.001), their torque kinetics parameters were similar. These findings highlight the specificity of gymnastics training, which markedly elevated the torque kinetics of young, prepubertal boys to adult levels, but only moderately affected peak torque. It is suggested that neurologic adaptations, such as enhanced firing and activation rates or increased type II motor-unit recruitment, as well as changes in musculotendinous stiffness, could explain these findings.
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Affiliation(s)
- Raffy Dotan
- Faculty of Applied Health Sciences, Brock University, 500 Glenridge Ave., St. Catharines, ON L2S 3A1, Canada.
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Spike shape analysis of surface electromyographic activity in wrist flexor and extensor muscles of the world's fastest drummer. Neurosci Lett 2012; 514:185-8. [PMID: 22414865 DOI: 10.1016/j.neulet.2012.02.089] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2011] [Revised: 02/11/2012] [Accepted: 02/26/2012] [Indexed: 11/20/2022]
Abstract
Spike shape analysis (SSA) is a method to infer motor unit (MU) activity by examining interference pattern of surface electromyography (sEMG). SSA has succeeded to assess neuromuscular adaptations after dynamic training; however, it has not been used to assess muscle activities during the dynamic movements as seen in music performance. The present study used SSA to investigate sEMG activities of wrist flexor and extensor muscles in the winner of a contest to find the world's fastest drummer (WFD) during performing rhythmic wrist flexion/extension movements with one hand using a handheld drumstick. SSA measures of the WFD were compared with those in the two control groups: non-drummers (NDs) and ordinary drummers (ODs). We found that the WFD showed significantly high mean spike frequency (MSF), short mean spike duration (MSD), and small mean number of peaks per spike (MNPPS) compared with the control groups. These results suggest that the WFD had exceptional MU activity such as higher MU discharge rate, more MU recruitment, and/or higher MU synchronization to achieve extraordinary fast 10-Hz drumming performance. SSA will be useful to investigate the muscle activity seen in music performance.
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Are training velocity and movement pattern important determinants of muscular rate of force development enhancement? Eur J Appl Physiol 2012; 112:3689-91. [DOI: 10.1007/s00421-012-2352-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2011] [Accepted: 02/04/2012] [Indexed: 10/14/2022]
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Bellumori M, Jaric S, Knight CA. The rate of force development scaling factor (RFD-SF): protocol, reliability, and muscle comparisons. Exp Brain Res 2011; 212:359-69. [DOI: 10.1007/s00221-011-2735-7] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2011] [Accepted: 05/15/2011] [Indexed: 12/22/2022]
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Abstract
UNLABELLED Previous studies in adults have demonstrated power athletes as having greater muscle force and muscle activation than nonathletes. Findings on endurance athletes are scarce and inconsistent. No comparable data on child athletes exist. PURPOSE This study compared peak torque (Tq), peak rate of torque development (RTD), and rate of muscle activation (EMG rise, Q30), in isometric knee extension (KE) and flexion (KF), in pre- and early-pubertal power- and endurance-trained boys vs minimally active nonathletes. METHODS Nine gymnasts, 12 swimmers, and 18 nonathletes (7-12 y), performed fast, maximal isometric KE and KF. Values for Tq, RTD, electromechanical delay (EMD), and Q30 were calculated from averaged torque and surface EMG traces. RESULTS No group differences were observed in Tq, normalized for muscle cross-sectional area. The Tq-normalized KE RTD was highest in power athletes (6.2 ± 1.9, 4.7 ± 1.2, 5.0 ± 1.5 N·m·s-1, for power, endurance, and nonathletes, respectively), whereas no group differences were observed for KF. The KE Q30 was significantly greater in power athletes, both in absolute terms and relative to peak EMG amplitude (9.8 ± 7.0, 5.9 ± 4.2, 4.4 ± 2.2 mV·ms and 1.7 ± 0.8, 1.1 ± 0.6, 0.9 ± 0.5 (mV·ms)/(mV) for power, endurance, and nonathletes, respectively), with no group differences in KF. The KE EMD tended to be shorter (P = .07) in power athletes during KE (71.0 ± 24.1, 87.8 ± 18.0, 88.4 ± 27.8 ms, for power, endurance, and nonathletes), with no group differences in KF. CONCLUSIONS Pre- and early-pubertal power athletes have enhanced rate of muscle activation in specifically trained muscles compared with controls or endurance athletes, suggesting that specific training can result in muscle activation-pattern changes before the onset of puberty.
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Gammage KL, Gabriel DA. Trait self-presentational concerns and performance in a maximal isometric strength test. J Strength Cond Res 2009; 23:1287-91. [PMID: 19528846 DOI: 10.1519/jsc.0b013e31819f1e40] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The purpose of the present study was to investigate (a) gender differences in performance (i.e., mean force) and trait self-presentational concerns (i.e., fear of negative evaluation [FNE] and social physique anxiety [SPA]) and (b) the relationship between trait self-presentational concerns and performance (force) on a maximal isometric strength test as commonly occurs in strength training studies. Participants consisted of 50 women and 46 men. All participants were right handed and physically active and were recruited from the general population of Brock University (Mage = 23.1 years, SD = 2.7). They completed measures of trait self-presentational concerns (SPA, FNE) before undergoing 5 maximal voluntary contractions of the elbow flexors. Results showed that, after adjusting for years weight training experience, men scored higher on force and women scored higher on SPA and FNE (all p's < 0.05). Further, for men, FNE significantly predicted force (p < 0.001). Thus, trait concerns over being evaluated by others are related to men's performance in a strength test. In strength testing settings, researchers and trainers should consider trait self-presentational concerns, which may impact actual performance.
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Affiliation(s)
- Kimberley L Gammage
- Department of Physical Education and Kinesiology, Exercise Intervention Laboratory and Electromyographic Kinesiology Laboratory, Brock University, St. Catharines, Ontario, Canada.
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Falk B, Usselman C, Dotan R, Brunton L, Klentrou P, Shaw J, Gabriel D. Child-adult differences in muscle strength and activation pattern during isometric elbow flexion and extension. Appl Physiol Nutr Metab 2009; 34:609-15. [PMID: 19767795 DOI: 10.1139/h09-020] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Muscle strength and activation were compared in boys and men during maximal voluntary elbow flexion and extension contractions. Peak torque, peak rate of torque development (d/dmax), rate of muscle activation, and electromechanical delay (EMD) were measured in 15 boys (aged 9.7 +/- 1.6 years) and 16 men (aged 22.1 +/- 2.8 years). During flexion, peak torque was significantly lower in boys than in men (19.5 +/- 5.8 vs. 68.5 +/- 11.0 Nm, respectively; p < 0.05), even when controlling for upper-arm cross-sectional area (CSA), and peak electromyography activity. Boys also exhibited a lower normalized d/dmax (7.2 +/- 1.7 vs. 9.5 +/- 1.6 (Nm.s-1).(Nm-1), respectively; p < 0.05) and a significantly longer EMD (75.5 +/- 28.4 vs. 47.6 +/- 17.5 ms, respectively). The pattern was similar for extension, except that group differences in peak torque were no longer significant when normalized for CSA. These results suggest that children may be less able to recruit or fully utilize their higher-threshold motor units, resulting in lower dimensionally normalized maximal torque and rate of torque development.
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Affiliation(s)
- Bareket Falk
- Department of Physical Education and Kinesiology, Brock University, St. Catharines, ON L2S 3A1, Canada.
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22
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Abstract
Ten prepubertal girls and 15 young women were tested for maximal torque, peak rate of torque development, electro-mechanical delay (EMD), and time to peak rate of torque development during isometric elbow flexion. Absolute peak torque (17.0 +/- 7.7 vs. 40.5 +/- 8.3 Nm) and peak rate of torque development (105.9 +/- 58.6 vs. 297.2 +/- 113.0 Nm s(-1)) were lower in the girls (p < .05). Normalized to muscle cross sectional area, torque was similar (8.27 +/- 2.74 vs. 8.44 +/- 1.65 Nm cm(-2)), as was peak rate of torque development, normalized to peak torque (6.21 +/- 1.94 vs. 7.30 +/- 2.26 Nm s(-1)/ Nm). Both, time to peak rate of torque development (123.8 +/- 36.0 vs. 110.5 +/- 52.6 ms) and EMD (73.2 +/- 28.6 vs. 51.9 +/- 25.6 ms), were longer in the girls, although EMD's difference only approached statistical significance (p = .06). Age-related isometric strength differences in females appear to be mainly muscle-size dependent. However, the time to peak torque and EMD findings suggest differential motor-unit activation which may functionally manifest itself in fast dynamic contractions.
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23
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Wijnberg ID, van Dam KG, Graaf-Roelfsema ED, Keizer HA, van Ginneken MME, Barneveld A, Breda EV, van der Kolk JH. (Over)training effects on quantitative electromyography and muscle enzyme activities in standardbred horses. J Appl Physiol (1985) 2008; 105:1746-53. [DOI: 10.1152/japplphysiol.01272.2007] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Too intensive training may lead to overreaching or overtraining. To study whether quantitative needle electromyography (QEMG) is more sensitive to detect training (mal)adaptation than muscle enzyme activities, 12 standardbred geldings trained for 32 wk in age-, breed-, and sex-matched fixed pairs. After a habituation and normal training (NT) phase ( phases 1 and 2, 4 and 18 wk, respectively), with increasing intensity and duration and frequency of training sessions, an intensified training (IT) group ( phase 3, 6 wk) and a control group (which continued training as in the last week of phase 2) were formed. Thereafter, all horses entered a reduced training phase ( phase 4, 4 wk). One hour before a standardized exercise test (SET; treadmill), QEMG analysis and biochemical enzyme activity were performed in muscle or in biopsies from vastus lateralis and pectoralis descendens muscle in order to identify causes of changes in exercise performance and eventual (mal)adaptation in skeletal muscle. NT resulted in a significant adaptation of QEMG parameters, whereas in muscle biopsies hexokinase activity was significantly decreased. Compared with NT controls, IT induced a stronger adaptation (e.g., higher amplitude, shorter duration, and fewer turns) in QEMG variables resembling potentially synchronization of individual motor unit fiber action potentials. Despite a 19% decrease in performance of the SET after IT, enzyme activities of 3-hydroxyacyl dehydrogenase and citrate synthase displayed similar increases in control and IT animals. We conclude that 1) QEMG analysis is a more sensitive tool to monitor training adaptation than muscle enzyme activities but does not discriminate between overreaching and normal training adaptations at this training level and 2) the decreased performance as noted in this study after IT originates most likely from a central (brain) rather than peripheral level.
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Tonson A, Ratel S, Le Fur Y, Cozzone P, Bendahan D. Effect of maturation on the relationship between muscle size and force production. Med Sci Sports Exerc 2008; 40:918-25. [PMID: 18408605 DOI: 10.1249/mss.0b013e3181641bed] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
PURPOSE Although it is well accepted that an increase in muscle size is linked to an increase in muscle force, the relationship between muscle size and maximal strength during maturation is still discussed. In the present study we aimed at determining whether maturation affects the relationship between muscle size and maximal strength, and we investigated the reasons accounting for the discrepancies among previous studies. METHODS Maximal isometric handgrip force (Fmax) and forearm muscle size were measured in 14 prepubertal boys (11.3 +/- 0.8 yr old), 16 adolescents (13.3 +/- 1.4 yr old), and 16 men (35.4 +/- 6.4 yr old). Anatomic maximal cross-sectional area (MCSA) and muscle volume (VM) were measured using MRI, and these results were compared with muscle volume (VL) obtained from anthropometric measurements. RESULTS Fmax was linearly correlated with VM (r2 = 0.90), VL (r2 = 0.85), and MCSA (r2 = 0.87), while VM was strongly correlated with VL (r2 = 0.90). The Fmax/VM ratio did not differ among groups, whereas Fmax/VL and Fmax/MCSA ratios were significantly higher in adults than in children and adolescents. These results demonstrated that, when compared with MRI, anthropometric measurements led to a systematic overestimation of muscle volume. In addition, this overestimation was significantly larger in children (43.1%) and adolescents (38.5%) as compared with adults (20.5%) (P < 0.05). CONCLUSION Our results showed that the maximal isometric strength exerted by the forearm muscles in humans is proportional to their size whatever the age, and that VM is the best index of muscle size during growth. The previously reported increased ability to produce maximal strength from childhood to adulthood could be explained by systematic bias introduced by the method used to characterize muscle size instead of physiological or neural changes.
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Affiliation(s)
- Anne Tonson
- Center for Magnetic Resonance in Biology and Medicine, Medical School of Marseille, Marseille, France
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25
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Gabriel DA, Lester SM, Lenhardt SA, Cambridge EDJ. Analysis of surface EMG spike shape across different levels of isometric force. J Neurosci Methods 2007; 159:146-52. [PMID: 16942800 DOI: 10.1016/j.jneumeth.2006.07.004] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2006] [Revised: 07/04/2006] [Accepted: 07/06/2006] [Indexed: 11/16/2022]
Abstract
This research evaluated changes in surface electromyographic (SEMG) spike shape across different levels of isometric force. Ninety-six subjects generated three 5-s isometric step contractions of the elbow flexors at 40, 60, 80, and 100% of maximal voluntary contraction (MVC). Force and bipolar SEMG activity were monitored concurrently. The mean spike amplitude (MSA) exhibited a linear increase across the four levels of force. The mean spike frequency (MSF) remained stable from 40 to 80% of MVC; it then decreased from 80 to 100% of MVC. There was a concomitant increase in mean spike slope (MSS) that indicates that the biceps brachii (BB) relied on the recruitment of higher threshold motor units (MUs) from 40 to 80% of MVC. However, there progressive decrease in the mean number of peaks per spike (MNPPS) that suggests that MU synchronization was additionally required to increase force from 80 to 100% of MVC. The spike shape measures, taken together, indicate that the decrease in frequency content of the signal was due to synchronization, not an increased probability of temporal overlap due an increase in rate-coding.
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Affiliation(s)
- David A Gabriel
- Electromyographic Kinesiology Laboratory, Brock University, 500 Glenridge Avenue, St. Catharines, Ontario, Canada L2S 3A1.
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26
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Barak Y, Ayalon M, Dvir Z. Spectral EMG changes in vastus medialis muscle following short range of motion isokinetic training. J Electromyogr Kinesiol 2006; 16:403-12. [PMID: 16324851 DOI: 10.1016/j.jelekin.2005.09.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2005] [Revised: 09/10/2005] [Accepted: 09/15/2005] [Indexed: 10/25/2022] Open
Abstract
This study was aimed at exploring the carryover effect of short range of motion (RoM) isokinetic conditioning on vastus medialis (VM) motor unit recruitment (MUR) across the full RoM. Fifty-five women were randomly assigned to one of four groups: G1 (n = 14) and G2 (n = 14) trained concentrically at 30 and 90 degrees /s, respectively whereas G3 (n = 13) and G4 (n = 14) trained similarly but using the eccentric mode. All 4 groups trained within 30-60 degrees of knee flexion. The training protocol consisted of 4 sets of 10 maximal repetitions, 3 times a week for 6 weeks. sEMG was recorded from the VM for analysis of mean frequency of the EMG power spectrum prior to the training period and 2 days after its termination. The EMG assessments took place during dynamic contractions within 3 angular RoM's: 85-60 degrees (R1), 60-30 degrees (R2) and 30-5 degrees (R3). In addition MUR was evaluated during isometric contractions at 10 degrees , 45 degrees and 80 degrees . Significant increases were observed in the MUR at R1, R2, and R3 during dynamic contractions as well as in all 3 angles during isometric contractions. These findings applied equally regardless of the mode of contraction and motion speed during training. The fact that MUR increased significantly within untrained RoM's may point out to the potential benefits of short RoM conditioning, particularly in those cases where, during specific phases of rehabilitation, a wider RoM may be contraindicative.
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Affiliation(s)
- Yaron Barak
- Department of Physical Therapy, Faculty of Social Welfare and Health Studies, Haifa University, Mount Carmel, Haifa 31905, Israel
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27
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Christos K, Konstantinos H, Dimitrios P, Eleni B. Differences in fatigability between the sexes during a sustained submaximal contraction protocol in prepubertal children. J Sports Sci 2006; 24:817-24. [PMID: 16815775 DOI: 10.1080/02640410500244598] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
The aim of this study was to determine whether there are differences in the fatigability of plantar flexor muscles during sustained submaximal contractions in prepubertal boys and girls. Fifteen boys (age 10.0 +/- 1.0 years) and 15 girls (age 9.8 +/- 0.9 years) participated in the study. The fatigue protocol consisted of a 10 min isometric plantar flexion at 20% of the maximal voluntary contraction. Immediately after this, five maximal isometric contractions were performed with a 3 min interval between contractions. During the experiment, electromyograms of the agonist muscles soleus and medial gastrocnemius and antagonist tibialis anterior were recorded. We observed no differences between the sexes (P < 0.05) in the decrease in torque or in the recovery rate after the fatigue protocol. Nor were there any differences between the sexes (P < 0.05) in agonist or antagonist muscle activation during the fatigue protocol and recovery period. The results indicate that there are no differences in fatigability between prepubertal boys and girls during submaximal sustained contractions, probably because the agonist and antagonist muscles were activated similarly in both sexes.
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Affiliation(s)
- Kotzamanidis Christos
- Department of Physical Education and Sport Science, Aristotelian University, Thessaloniki, Greece.
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28
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Calder KM, Gabriel DA. Adaptations during familiarization to resistive exercise. J Electromyogr Kinesiol 2006; 17:328-35. [PMID: 16740395 DOI: 10.1016/j.jelekin.2006.02.006] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2005] [Revised: 02/07/2006] [Accepted: 02/25/2006] [Indexed: 10/24/2022] Open
Abstract
This study focused on adaptations during familiarization to resistive exercise. It was also determined if familiarization requires one or more sessions. Twenty-six sedentary, college-aged females were matched and randomly assigned to one of two groups. Measurements were obtained during the initial familiarization period (Group 1: 15 trials on 1 day, Group 2: 5 trials on each of three consecutive days), and during retention tests scheduled two weeks and 3 months after the first test session. Elbow flexion torque and surface electromyography (SEMG) of the biceps and triceps were monitored concurrently. There were no significant differences between groups for any of the criterion measures. There was a significant (p<0.05) increase (12.4 Nm, or 38.8%) in maximal isometric elbow flexion torque. Biceps (agonist) root-mean-square (RMS) SEMG exhibited a significant (p<0.05) increase of 95 microV (29%). Triceps (antagonist) RMS SEMG underwent alternating decreases then increases, and each change was significant (p<0.05). The ratio of biceps to triceps RMS SEMG was used to assess cocontraction, and it followed the same pattern of change as triceps RMS SEMG. We concluded that both groups responded in the same way to testing, regardless of the pattern of the first 15 contractions. The increase in maximal isometric elbow flexion torque was due to neural drive to the bicep (agonist). There was a low level of triceps (antagonist) cocontraction to provide joint stability, and it was adjusted throughout the duration of testing.
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Affiliation(s)
- Kristina M Calder
- Department of Physical Education and Kinesiology, Kinesiological Electromyographic Kinesiology Laboratory, Brock University, St. Catharines, Ont., Canada L2S 3A1
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29
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Abstract
It is generally accepted that neural factors play an important role in muscle strength gains. This article reviews the neural adaptations in strength, with the goal of laying the foundations for practical applications in sports medicine and rehabilitation. An increase in muscular strength without noticeable hypertrophy is the first line of evidence for neural involvement in acquisition of muscular strength. The use of surface electromyographic (SEMG) techniques reveal that strength gains in the early phase of a training regimen are associated with an increase in the amplitude of SEMG activity. This has been interpreted as an increase in neural drive, which denotes the magnitude of efferent neural output from the CNS to active muscle fibres. However, SEMG activity is a global measure of muscle activity. Underlying alterations in SEMG activity are changes in motor unit firing patterns as measured by indwelling (wire or needle) electrodes. Some studies have reported a transient increase in motor unit firing rate. Training-related increases in the rate of tension development have also been linked with an increased probability of doublet firing in individual motor units. A doublet is a very short interspike interval in a motor unit train, and usually occurs at the onset of a muscular contraction. Motor unit synchronisation is another possible mechanism for increases in muscle strength, but has yet to be definitely demonstrated. There are several lines of evidence for central control of training-related adaptation to resistive exercise. Mental practice using imagined contractions has been shown to increase the excitability of the cortical areas involved in movement and motion planning. However, training using imagined contractions is unlikely to be as effective as physical training, and it may be more applicable to rehabilitation. Retention of strength gains after dissipation of physiological effects demonstrates a strong practice effect. Bilateral contractions are associated with lower SEMG and strength compared with unilateral contractions of the same muscle group. SEMG magnitude is lower for eccentric contractions than for concentric contractions. However, resistive training can reverse these trends. The last line of evidence presented involves the notion that unilateral resistive exercise of a specific limb will also result in training effects in the unexercised contralateral limb (cross-transfer or cross-education). Peripheral involvement in training-related strength increases is much more uncertain. Changes in the sensory receptors (i.e. Golgi tendon organs) may lead to disinhibition and an increased expression of muscular force. Agonist muscle activity results in limb movement in the desired direction, while antagonist activity opposes that motion. Both decreases and increases in co-activation of the antagonist have been demonstrated. A reduction in antagonist co-activation would allow increased expression of agonist muscle force, while an increase in antagonist co-activation is important for maintaining the integrity of the joint. Thus far, it is not clear what the CNS will optimise: force production or joint integrity. The following recommendations are made by the authors based on the existing literature. Motor learning theory and imagined contractions should be incorporated into strength-training practice. Static contractions at greater muscle lengths will transfer across more joint angles. Submaximal eccentric contractions should be used when there are issues of muscle pain, detraining or limb immobilisation. The reversal of antagonists (antagonist-to-agonist) proprioceptive neuromuscular facilitation contraction pattern would be useful to increase the rate of tension development in older adults, thus serving as an important prophylactic in preventing falls. When evaluating the neural changes induced by strength training using EMG recording, antagonist EMG activity should always be measured and evaluated.
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Affiliation(s)
- David A Gabriel
- Department of Physical Education and Kinesiology, Brock University, St Catharines, Ontario, Canada.
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Gabriel DA. Changes in kinematic and EMG variability while practicing a maximal performance task. J Electromyogr Kinesiol 2002; 12:407-12. [PMID: 12223174 DOI: 10.1016/s1050-6411(02)00026-3] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
Abstract
This paper examines changes in the variability of electromyographic (EMG) activity and kinematics as a result of practicing a maximal performance task. Eight subjects performed rapid elbow flexion to a target in the horizontal plane. Four hundred trials were distributed equally over four practice sessions. A potentiometer at the elbow axis of rotation of a manipulandum recorded the angular displacement. The EMG activity of the biceps and the triceps brachii was monitored using Beckman surface electrodes. Limb speed increased while both target error and trajectory (velocity versus position) variability decreased. There was an increase in the absolute measure of total EMG variability (the first standard deviation at each point of the biceps and triceps waveform multiplied together). However, the coefficient of variation (the first standard deviation divided by the mean and the result multiplied by 100) of the mean amplitude value of the individual EMG bursts decreased. The variability of triceps motor time also decreased while the variability biceps motor time remained unchanged. The results demonstrated a clear relationship between kinematic and EMG variability. The EMG and the trajectory data suggest that practice resulted in greater central nervous system control over both the spatial-temporal aspects of movement and the magnitude of the biceps and triceps muscle force-impulses.
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Affiliation(s)
- David A Gabriel
- Biomechanics Laboratory, Brock University, St Catharines, ON, Canada L2S 3A1.
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Gabriel DA, Basford JR, An KN. Assessing fatigue with electromyographic spike parameters. IEEE ENGINEERING IN MEDICINE AND BIOLOGY MAGAZINE : THE QUARTERLY MAGAZINE OF THE ENGINEERING IN MEDICINE & BIOLOGY SOCIETY 2001; 20:90-6. [PMID: 11838263 DOI: 10.1109/51.982280] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- D A Gabriel
- Department of Physical Education and Kinesiology, Brock University.
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