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Göpfert B, Schärer C, Tacchelli L, Gross M, Lüthy F, Hübner K. Frequency Shifts in Muscle Activation during Static Strength Elements on the Rings before and after an Eccentric Training Intervention in Male Gymnasts. J Funct Morphol Kinesiol 2022; 7:jfmk7010028. [PMID: 35323611 PMCID: PMC8956077 DOI: 10.3390/jfmk7010028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Revised: 03/07/2022] [Accepted: 03/10/2022] [Indexed: 11/16/2022] Open
Abstract
During ring performance in men's gymnastics, static strength elements require a high level of maximal muscular strength. The aim of the study was to analyze the effect of a four-week eccentric-isokinetic training intervention in the frequency spectra of the wavelet-transformed electromyogram (EMG) during the two static strength elements, the swallow and support scale, in different time intervals during the performance. The gymnasts performed an instrumented movement analysis on the rings, once before the intervention and twice after. For both elements, the results showed a lower congruence in the correlation of the frequency spectra between the first and the last 0.5 s interval than between the first and second 0.5 s intervals, which was indicated by a shift toward the predominant frequency around the wavelet with a center frequency of 62 Hz (Wavelet W10). Furthermore, in both elements, there was a significant increase in the congruence of the frequency spectra after the intervention between the first and second 0.5 s intervals, but not between the first and last ones. In conclusion, the EMG wavelet spectra presented changes corresponding to the performance gain with the eccentric training intervention, and showed the frequency shift toward a predominant frequency due to acute muscular fatigue.
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Affiliation(s)
- Beat Göpfert
- Department Biomedical Engineering (DBE), University of Basel, 4001 Basel, Switzerland
- Correspondence:
| | - Christoph Schärer
- Swiss Federal Institute of Sport Magglingen (SFISM), 2532 Magglingen, Switzerland; (C.S.); (M.G.); (F.L.); (K.H.)
| | - Lisa Tacchelli
- Movement and Sport Science, Department of Medicine, University of Fribourg, 1700 Fribourg, Switzerland;
| | - Micah Gross
- Swiss Federal Institute of Sport Magglingen (SFISM), 2532 Magglingen, Switzerland; (C.S.); (M.G.); (F.L.); (K.H.)
| | - Fabian Lüthy
- Swiss Federal Institute of Sport Magglingen (SFISM), 2532 Magglingen, Switzerland; (C.S.); (M.G.); (F.L.); (K.H.)
| | - Klaus Hübner
- Swiss Federal Institute of Sport Magglingen (SFISM), 2532 Magglingen, Switzerland; (C.S.); (M.G.); (F.L.); (K.H.)
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Willberg C, Zentgraf K, Behringer M. The Effect of Lower-Body Blood Flow Restriction on Static and Perturbated Stable Stand in Young, Healthy Adults. Front Hum Neurosci 2021; 15:756230. [PMID: 34744667 PMCID: PMC8570169 DOI: 10.3389/fnhum.2021.756230] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2021] [Accepted: 10/04/2021] [Indexed: 11/13/2022] Open
Abstract
Muscular fatigue can affect postural control processes by impacting on the neuromuscular and somatosensory system. It is assumed that this leads to an increased risk of injury, especially in sports such as alpine skiing that expose the body to strong and rapidly changing external forces. In this context, posture constraints and contraction-related muscular pressure may lead to muscular deoxygenation. This study investigates whether these constraints and pressure affect static and dynamic postural control. To simulate impaired blood flow in sports within a laboratory task, oxygen saturation was manipulated locally by using an inflatable cuff to induce blood flow restriction (BFR). Twenty-three subjects were asked to stand on a perturbatable platform used to assess postural-related movements. Using a 2 × 2 within-subject design, each participant performed postural control tasks both with and without BFR. BFR resulted in lower oxygenation of the m. quadriceps femoris (p = 0.024) and was associated with a significantly lower time to exhaustion (TTE) compared to the non-restricted condition [F(1,19) = 16.22, p < 0.001, ηp2 = 0.46]. Perturbation resulted in a significantly increased TTE [F(1,19) = 7.28, p = 0.014, ηp2 = 0.277]. There were no significant effects on static and dynamic postural control within the saturation conditions. The present data indicate that BFR conditions leads to deoxygenation and a reduced TTE. Postural control and the ability to regain stability after perturbation were not affected within this investigation.
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Affiliation(s)
- Christina Willberg
- Institute of Sport Sciences, Movement Sciences and Training in Sports, Goethe University Frankfurt, Frankfurt, Germany
| | - Karen Zentgraf
- Institute of Sport Sciences, Movement Sciences and Training in Sports, Goethe University Frankfurt, Frankfurt, Germany
| | - Michael Behringer
- Institute of Sport Sciences, Sports Medicine and Exercise Physiology, Goethe University Frankfurt, Frankfurt, Germany
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Hoitz F, Vienneau J, Nigg BM. Influence of running shoes on muscle activity. PLoS One 2020; 15:e0239852. [PMID: 33027311 PMCID: PMC7540877 DOI: 10.1371/journal.pone.0239852] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Accepted: 09/14/2020] [Indexed: 11/28/2022] Open
Abstract
Studies on the paradigm of the preferred movement path are scarce, and as a result, many aspects of the paradigm remain elusive. It remains unknown, for instance, how muscle activity adapts when differences in joint kinematics, due to altered running conditions, are of low / high magnitudes. Therefore, the purpose of this work was to investigate changes in muscle activity of the lower extremities in runners with minimal (≤ 3°) or substantial (> 3°) mean absolute differences in the ankle and knee joint angle trajectories when subjected to different running footwear. Mean absolute differences in the integral of the muscle activity were quantified for the tibialis anterior (TA), peroneus longus (PL), gastrocnemius medialis (GM), soleus (SO), vastus lateralis (VL), and biceps femoris (BF) muscles during over ground running. In runners with minimal changes in 3D joint angle trajectories (≤ 3°), muscle activity was found to change drastically when comparing barefoot to shod running (TA: 35%; PL: 11%; GM: 17%; SO: 10%; VL: 27%; BF: 16%), and minimally when comparing shod to shod running (TA: 10%; PL: 9%; GM: 13%; SO: 8%; VL: 8%; BF: 12%). For runners who showed substantial changes in joint angle trajectories (> 3°), muscle activity changed drastically in barefoot to shod comparisons (TA: 39%; PL: 14%; GM: 16%; SO: 16%; VL: 25%; BF: 24%). It was concluded that a movement path can be maintained with small adaptations in muscle activation when running conditions are similar, while large adaptations in muscle activation are needed when running conditions are substantially different.
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Affiliation(s)
- Fabian Hoitz
- Biomedical Engineering, Schulich School of Engineering, University of Calgary, Calgary, Alberta, Canada
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada
- * E-mail:
| | - Jordyn Vienneau
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada
| | - Benno M. Nigg
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada
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Alcan V, Kaya H, Zinnuroğlu M, Karataş GK, Canal MR. A novel approach to the diagnostic assessment of carpal tunnel syndrome based on the frequency domain of the compound muscle action potential. ACTA ACUST UNITED AC 2020; 65:61-71. [PMID: 31377730 DOI: 10.1515/bmt-2018-0077] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Accepted: 03/18/2019] [Indexed: 11/15/2022]
Abstract
Conventional electrophysiological (EP) tests may yield ambiguous or false-negative results in some patients with signs and symptoms of carpal tunnel syndrome (CTS). Therefore, researchers tend to investigate new parameters to improve the sensitivity and specificity of EP tests. We aimed to investigate the mean and maximum power of the compound muscle action potential (CMAP) as a novel diagnostic parameter, by evaluating diagnosis and classification performance using the supervised Kohonen self-organizing map (SOM) network models. The CMAPs were analyzed using the fast Fourier transform (FFT). The mean and maximum power parameters were calculated from the power spectrum. A counter-propagation artificial neural network (CPANN), supervised Kohonen network (SKN) and XY-fused network (XYF) were compared to evaluate the classification and diagnostic performance of the parameters using the confusion matrix. The mean and maximum power of the CMAP were significantly lower in patients with CTS than in the normal group (p < 0.05), and the XYF network had the best total performance of classification with 91.4%. This study suggests that the mean and maximum power of the CMAP can be considered as less time-consuming parameters for the diagnosis of CTS without using additional EP tests which can be uncomfortable for the patient due to poor tolerance to electrical stimulation.
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Affiliation(s)
- Veysel Alcan
- Department of Software Engineering, Faculty of Technology, Tarsus University, Mersin 33400, Turkey
| | - Hilal Kaya
- Department of Computer Engineering, Faculty of Engineering and Natural Science, Ankara Yıldırım Beyazıt University, Ankara 06010, Turkey
| | - Murat Zinnuroğlu
- Department of Physical Medicine and Rehabilitation, School of Medicine, Gazi University, Ankara 06500, Turkey
| | - Gülçin Kaymak Karataş
- Department of Physical Medicine and Rehabilitation, School of Medicine, Gazi University, Ankara 06500, Turkey
| | - Mehmet Rahmi Canal
- Department of Biomedical Engineering, Faculty of Engineering, İnönü University, Malatya 44280, Turkey
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Mohr M, von Tscharner V, Emery CA, Nigg BM. Classification of gait muscle activation patterns according to knee injury history using a support vector machine approach. Hum Mov Sci 2019; 66:335-346. [PMID: 31146192 DOI: 10.1016/j.humov.2019.05.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2018] [Revised: 05/14/2019] [Accepted: 05/15/2019] [Indexed: 11/26/2022]
Abstract
Abnormal muscle activation patterns during gait following knee injury that persist past the acute injury and rehabilitation phase (>three years) are not well characterized but may be related to post-traumatic knee osteoarthritis. The aim was to characterize the abnormal muscle activity from electromyograms of five leg muscles that were recorded during treadmill walking for young adults with and without a previous knee injury 3-12 years prior. The wavelet transformed and amplitude normalized electromyograms yielded intensity patterns that reflect the muscle activity of these muscles resolved in time and frequency. Patterns belonging to the affected or unaffected leg in previously injured participants and patterns belonging to a previously injured vs. uninjured participant were grouped and then classified using a principal component analysis followed by a support vector machine. A leave-one-out cross-validation was used to test the model significance and generalization. The results showed that trained classifiers could successfully recognize whether muscle activation patterns belonged to the affected or unaffected leg of previously injured individuals. Classification rates of 83% were obtained for all subjects, 100% for females only, indicating sex-specific knee injury effects. In contrast, it was not possible to discriminate between patterns belonging to the previously injured legs or dominant legs of control subjects. For females, the injured leg showed a stronger muscle activity for hamstring muscles and a lower activity for the vastus lateralis. In conclusion, systematic knee injury effects on the neuromuscular control of the knee during gait were present 3-12 years later.
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Affiliation(s)
- Maurice Mohr
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Alberta, Canada; Sport Injury Prevention Research Centre, Faculty of Kinesiology, University of Calgary, Alberta, Canada.
| | - Vinzenz von Tscharner
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Alberta, Canada
| | - Carolyn A Emery
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Alberta, Canada; Sport Injury Prevention Research Centre, Faculty of Kinesiology, University of Calgary, Alberta, Canada; The Alberta Children's Hospital Research Institute and McCaig Institute for Bone and Joint Health, Cumming School of Medicine, University of Calgary, Alberta, Canada
| | - Benno M Nigg
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Alberta, Canada
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Brueckner D, Göpfert B, Kiss R, Muehlbauer T. Effects of motor practice on learning a dynamic balance task in healthy young adults: A wavelet-based time-frequency analysis. Gait Posture 2019; 70:264-269. [PMID: 30909006 DOI: 10.1016/j.gaitpost.2019.03.019] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Revised: 03/06/2019] [Accepted: 03/20/2019] [Indexed: 02/02/2023]
Abstract
BACKGROUND Previous research showed changes in amplitude- or time-derived measures of electromyographic (EMG) activity with motor learning. However, an analysis of the EMG spectral content (e.g., via wavelet technique) has not been included in these investigations yet. OBJECTIVE The aim of this study was to use conventional, amplitude-derived EMG parameters along with modern, wavelet-based time-frequency EMG measures to assess the effects of motor practice on learning a dynamic balance task. METHODS Nineteen young male adults (mean age: 26 ± 6 years) practiced a dynamic balance task for two days. Delayed retention test was performed on the third day. On a behavioral level, the root-mean-square error (RMSE) of the stability platform angle was calculated and used as outcome measure. On a neuromuscular level, EMG data from the tibialis anterior (TA) and the gastrocnemius medialis (GM) muscle were unilaterally recorded and analysed by calculating the integrated EMG (iEMG) and the EMG intensity (via continuous wavelet transforms). RESULTS Two days of practice resulted in significantly improved balance performance (i.e., lower RMSE) and TA/GM activation (i.e., reduced iEMG and EMG intensity) that was still present during the retention test on day 3. There was also evidence of practice-related changes in the EMG intensity pattern as indicated by an intensity shift from higher to lower frequency components. CONCLUSIONS We conclude that motor practice leads to improvements in movement effectiveness as indicated by reduced RMSE and in movement efficiency (i.e., decreased iEMG and EMG intensity, intensity shift). In addition to conventional amplitude-derived EMG parameters, modern, wavelet-based time-frequency EMG measures are appropriate to detect practice-related changes in muscle activation.
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Affiliation(s)
- Dennis Brueckner
- Division of Movement and Training Sciences/Biomechanics of Sport, University of Duisburg-Essen, Essen, Germany
| | - Beat Göpfert
- Center of Biomechanics and Biocalorimetry, Department of Biomedical Engineering, University of Basel, Basel, Switzerland
| | - Rainer Kiss
- Department of Health and Social Affairs, FHM Bielefeld - University of Applied Sciences, Bielefeld, Germany
| | - Thomas Muehlbauer
- Division of Movement and Training Sciences/Biomechanics of Sport, University of Duisburg-Essen, Essen, Germany.
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von Tscharner V, Ullrich M, Mohr M, Comaduran Marquez D, Nigg BM. A wavelet based time frequency analysis of electromyograms to group steps of runners into clusters that contain similar muscle activation patterns. PLoS One 2018; 13:e0195125. [PMID: 29668731 PMCID: PMC5906018 DOI: 10.1371/journal.pone.0195125] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2017] [Accepted: 03/16/2018] [Indexed: 11/18/2022] Open
Abstract
PURPOSE To wavelet transform the electromyograms of the vastii muscles and generate wavelet intensity patterns (WIP) of runners. Test the hypotheses: 1) The WIP of the vastus medialis (VM) and vastus lateralis (VL) of one step are more similar than the WIPs of these two muscles, offset by one step. 2) The WIPs within one muscle differ by having maximal intensities in specific frequency bands and these intensities are not always occurring at the same time after heel strike. 3) The WIPs that were recorded form one muscle for all steps while running can be grouped into clusters with similar WIPs. It is expected that clusters might have distinctly different, cluster specific mean WIPs. METHODS The EMG of the vastii muscles from at least 1000 steps from twelve runners were recorded using a bipolar current amplifier and yielded WIPs. Based on the weights obtained after a principal component analysis the dissimilarities (1-correlation) between the WIPs were computed. The dissimilarities were submitted to a hierarchical cluster analysis to search for groups of steps with similar WIPs. The clusters formed by random surrogate WIPs were used to determine whether the groups were likely to be created in a non-random manner. RESULTS The steps were grouped in clusters showing similar WIPs. The grouping was based on the frequency bands and their timing showing that they represented defining parts of the WIPs. The correlations between the WIPs of the vastii muscles that were recorded during the same step were higher than the correlations of WPIs that were recorded during consecutive steps, indicating the non-randomness of the WIPs. CONCLUSIONS The spectral power of EMGs while running varies during the stance phase in time and frequency, therefore a time averaged power spectrum cannot reflect the timing of events that occur while running. It seems likely that there might be a set of predefined patterns that are used upon demand to stabilize the movement.
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Affiliation(s)
- Vinzenz von Tscharner
- Faculty of Kinesiology, Human Performance Laboratory, University of Calgary, Calgary, Alberta, Canada
| | - Martin Ullrich
- Faculty of Kinesiology, Human Performance Laboratory, University of Calgary, Calgary, Alberta, Canada
| | - Maurice Mohr
- Faculty of Kinesiology, Human Performance Laboratory, University of Calgary, Calgary, Alberta, Canada
| | - Daniel Comaduran Marquez
- Faculty of Kinesiology, Human Performance Laboratory, University of Calgary, Calgary, Alberta, Canada
| | - Benno M. Nigg
- Faculty of Kinesiology, Human Performance Laboratory, University of Calgary, Calgary, Alberta, Canada
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8
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Grossi S, Grassi F, Galleani L, Bianchi F, Sibona Masi A, Conte MR. Atrial Conduction Velocity Correlates with Frequency Content of Bipolar Signal. PACING AND CLINICAL ELECTROPHYSIOLOGY: PACE 2016; 39:814-21. [PMID: 27196672 DOI: 10.1111/pace.12884] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2016] [Revised: 03/31/2016] [Accepted: 04/30/2016] [Indexed: 01/22/2023]
Abstract
BACKGROUND Anisotropy in conduction velocity (CV) is a key substrate abnormality influencing atrial arrhythmias. In skeletal muscle fibers, CV and frequency content of the surface electromyogram signal are directly related. We hypothesized that in human atria the frequency content of the bipolar signal, recorded on the endocardial surface, is directly related to the local CV. METHODS In 15 patients submitted to ablation of supraventricular arrhythmias, incremental pacing was performed through an octapolar catheter inserted into the coronary sinus (CS), alternatively from both extremities in two different sequences: CS bipole 1-2 as the pacing site and CS bipole 7-8 as the detection site in the first, and vice versa in the second. The pacing cycle length (PCL) was stepwise decreased from 600 ms to 500 ms, 400 ms, 300 ms, until 250 ms. Estimation of the CV was performed as the ratio between the distance traveled by the propagating pulse and the propagation time. The frequency distribution of the signal energy was estimated using the fast Fourier transform, and the characteristic frequency (CF) was estimated as the barycenter of the frequency spectrum. RESULTS A total of 2,496 bipolar signals were analyzed; CV and CF were estimated and compared. The single patient and group data analysis showed a significant direct correlation between CV and CF of the local bipolar signal. CONCLUSIONS Comparing the degree of spectral compression among signals registered in different points of the endocardial cardiac surface in response to decreasing PCL enables to map local differences in CV, a useful arrhythmogenic substrate index.
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Affiliation(s)
- Stefano Grossi
- Cardiology Department, Mauriziano Hospital, Turin, Italy
| | - Francesco Grassi
- Department of Electronics and Telecommunications, Politecnico di Torino, Italy
| | - Lorenzo Galleani
- Department of Electronics and Telecommunications, Politecnico di Torino, Italy
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Papa EV, Garg H, Dibble LE. Acute effects of muscle fatigue on anticipatory and reactive postural control in older individuals: a systematic review of the evidence. J Geriatr Phys Ther 2015; 38:40-8. [PMID: 24978932 DOI: 10.1519/jpt.0000000000000026] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
BACKGROUND Falls are the leading cause of traumatic brain injury and fractures and the No. 1 cause of emergency department visits by older adults. Although declines in muscle strength and sensory function contribute to increased falls in older adults, skeletal muscle fatigue is often overlooked as an additional contributor to fall risk. In an effort to increase awareness of the detrimental effects of skeletal muscle fatigue on postural control, we sought to systematically review research studies examining this issue. PURPOSE The specific purpose of this review was to provide a detailed assessment of how anticipatory and reactive postural control tasks are influenced by acute muscle fatigue in healthy older individuals. METHODS An extensive search was performed using the CINAHL, Scopus, PubMed, SPORTDiscus, and AgeLine databases for the period from inception of each database to June 2013. This systematic review used standardized search criteria and quality assessments via the American Academy for Cerebral Palsy and Developmental Medicine Methodology to Develop Systematic Reviews of Treatment Interventions (2008 version, revision 1.2, AACPDM, Milwaukee, Wisconsin). RESULTS A total of 334 citations were found. Six studies were selected for inclusion, whereas 328 studies were excluded from the analytical review. The majority of articles (5 of 6) utilized reactive postural control paradigms. All studies incorporated extrinsic measures of muscle fatigue, such as declines in maximal voluntary contraction or available active range of motion. The most common biomechanical postural control task outcomes were spatial measures, temporal measures, and end-points of lower extremity joint kinetics. CONCLUSION On the basis of systematic review of relevant literature, it appears that muscle fatigue induces clear deteriorations in reactive postural control. A paucity of high-quality studies examining anticipatory postural control supports the need for further research in this area. These results should serve to heighten awareness regarding the potential negative effects of acute muscle fatigue on postural control and support the examination of muscle endurance training as a fall risk intervention in future studies.
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Affiliation(s)
- Evan V Papa
- 1Department of Physical Therapy, University of North Texas Health Science Center, Fort Worth. 2Department of Physical Therapy, University of Utah, Salt Lake City
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von Tscharner V, Maurer C, Nigg BM. Correlations and coherence of monopolar EMG-currents of the medial gastrocnemius muscle in proximal and distal compartments. Front Physiol 2014; 5:223. [PMID: 24987375 PMCID: PMC4060492 DOI: 10.3389/fphys.2014.00223] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2014] [Accepted: 05/27/2014] [Indexed: 11/13/2022] Open
Abstract
The penniform gastrocnemius muscle contains multiple heads in the proximal regions, and the aponeuroses are attached to the Achilles tendon. The multiple head structure lead to the assumption that different regions of the muscle must be activated compartment wise. The purpose of this study was to compare the correlation and coherence of EMG-currents within and between proximal and distal compartments of the medial gastrocnemius muscle, which reflect underling synchronization of motor units. It was hypothesized and shown that phase inverted signals represent a property that discriminates compartments. However, the phase inverted and non-inverted signals showed values of correlations that were indicative for highly synchronized signals. The correlation increased with the complexity of the task and was higher for the calf rising movement than while balancing in a tiptoe position. Because the muscle fibers do not span the whole length of the muscles, one has to conclude that the MUs were synchronized by synchronizing the various motor nerves. This study shows that it is essential to measure monopolar signals and use non-isometric contractions to observe synchronization of the EMG-signals. One could speculate that compartmental differences can only be observed if more complex movements that generate rotational forces at the knee or ankle are used.
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Affiliation(s)
| | | | - Benno M Nigg
- Human Performance Laboratory, University of Calgary Calgary, AB, Canada
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Abstract
This study investigated the relationships between thumb muscle activity and thumb operating tasks on a smartphone touch screen with one-hand posture. Six muscles in the right thumb and forearm were targeted in this study, namely adductor pollicis, flexor pollicis brevis, abductor pollicis brevis (APB), abductor pollicis longus, first dorsal interosseous (FDI) and extensor digitorum. The performance measures showed that the thumb developed fatigue rapidly when tapping on smaller buttons (diameter: 9 mm compared with 3 mm), and moved more slowly in flexion-extension than in adduction-abduction orientation. Meanwhile, the electromyography and perceived exertion values of FDI significantly increased in small button and flexion-extension tasks, while those of APB were greater in the adduction-abduction task. This study reveals that muscle effort among thumb muscles on a touch screen smartphone varies according to the task, and suggests that the use of small touch buttons should be minimised for better thumb performance.
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Affiliation(s)
- Jinghong Xiong
- a Graduate School of Design , Kyushu University , Fukuoka , Japan
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12
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von Tscharner V, Maurer C, Ruf F, Nigg BM. Comparison of electromyographic signals from monopolar current and potential amplifiers derived from a penniform muscle, the gastrocnemius medialis. J Electromyogr Kinesiol 2013; 23:1044-51. [PMID: 23938250 DOI: 10.1016/j.jelekin.2013.07.011] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2012] [Revised: 06/25/2013] [Accepted: 07/09/2013] [Indexed: 11/26/2022] Open
Abstract
Electromyograms (EMGs) are measured by bipolar surface electrodes that quantify potential differences. Bipolar potentials over penniform muscles may be associated with errors. Our assumption was that muscle activity can be quantified more reliably and with a higher spatial resolution using current measurements. The purpose of this work is: (a) to introduce the concept of current measurements to detect muscle activity, (b) to show the coherences observed over a segment of a typical penniform muscle, the gastrocnemius medialis where one would expect a synchronicity of the activation, and (c) to show the amount of mixing that is caused by the finite inter electrode resistance. A current amplifier was developed. EMGs were recorded at 40% of maximum voluntary contraction during isometric contractions of the gastrocnemius medialis. EMGs of twelve persons were recorded with an array of four peripheral and one central electrode. Monopolar EMGs were recorded for "all-potential", "center at current" and "all-current" conditions. Coherence revealed the similarity of signals recorded from neighboring electrodes. Coherence was high for the "all-potential", significant for the "current at center" condition and disappeared in the "all-current" condition. It was concluded that EMG array recordings strongly depends on the measurement configuration. The proposed current amplifier significantly improves spatial resolution of EMG array recordings because the inter-electrode cross talk is reduced.
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Affiliation(s)
- Vinzenz von Tscharner
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada.
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13
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Maurer C, von Tscharner V, Nigg BM. Speed-dependent variation in the Piper rhythm. J Electromyogr Kinesiol 2013; 23:673-8. [DOI: 10.1016/j.jelekin.2013.01.007] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2012] [Revised: 01/11/2013] [Accepted: 01/11/2013] [Indexed: 10/27/2022] Open
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Analysis of damped tissue vibrations in time-frequency space: A wavelet-based approach. J Biomech 2012; 45:2855-9. [DOI: 10.1016/j.jbiomech.2012.08.027] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2012] [Revised: 08/17/2012] [Accepted: 08/22/2012] [Indexed: 11/24/2022]
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15
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Removal of the electrocardiogram signal from surface EMG recordings using non-linearly scaled wavelets. J Electromyogr Kinesiol 2011; 21:683-8. [DOI: 10.1016/j.jelekin.2011.03.004] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2010] [Revised: 03/12/2011] [Accepted: 03/12/2011] [Indexed: 11/23/2022] Open
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Tscharner VV, Barandun M, Stirling LM. Piper rhythm of the electromyograms of the abductor pollicis brevis muscle during isometric contractions. J Electromyogr Kinesiol 2011; 21:184-9. [DOI: 10.1016/j.jelekin.2010.10.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2009] [Revised: 10/10/2010] [Accepted: 10/11/2010] [Indexed: 10/18/2022] Open
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von Tscharner V, Barandun M, Stirling LM. Fatigue-related decrease in Piper rhythm frequency of the abductor pollicis brevis muscle during isometric contractions. J Electromyogr Kinesiol 2011; 21:190-5. [DOI: 10.1016/j.jelekin.2010.10.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2010] [Revised: 08/08/2010] [Accepted: 10/12/2010] [Indexed: 11/25/2022] Open
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von Tscharner V, Barandun M. Wavelet based correlation and coherence analysis reveals frequency dependent motor unit conduction velocity of the abductor pollicis brevis muscle. J Electromyogr Kinesiol 2010; 20:1088-96. [PMID: 20634091 DOI: 10.1016/j.jelekin.2010.06.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2009] [Revised: 04/25/2010] [Accepted: 06/23/2010] [Indexed: 01/22/2023] Open
Abstract
The purpose of this study was to investigate the motorunit conduction velocity (CV) as a function of frequency. A wavelet based correlation and coherence analysis was introduced to measure CV as a function of frequency. Based on the most simple assumption that the power spectra of the motor unit action potential is shifted to higher frequencies with increasing CV, we hypothesized that there would be a monotonic or linear trend of increasing CV with frequency. This trend was only confirmed at higher frequencies. At lower frequencies the trend was often reversed leading to a decrease in CV with increasing frequency. Thus the CV was high at low frequencies, went through a minimum at about 170 Hz and increased at higher frequencies, as expected. The observed CV at low frequencies could not be fully explained by assuming non-propagating signals or variable groups of motor units. We concluded that spectra and CV contain partly independent information about the muscles and that the wavelet based method provides the tools to measure them both simultaneously.
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Papaiordanidou M, Guiraud D, Varray A. Does central fatigue exist under low-frequency stimulation of a low fatigue-resistant muscle? Eur J Appl Physiol 2010; 110:815-23. [DOI: 10.1007/s00421-010-1565-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/24/2010] [Indexed: 11/30/2022]
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Huber C, Göpfert B, Kugler PFX, von Tscharner V. The Effect of Sprint and Endurance Training on Electromyogram Signal Analysis by Wavelets. J Strength Cond Res 2010; 24:1527-36. [DOI: 10.1519/jsc.0b013e3181dc42f6] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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