scholarly journals Fatiguing effects of indirect vibration stimulation in upper limb muscles: pre, post and during isometric contractions superimposed on upper limb vibration

2019 ◽  
Vol 6 (10) ◽  
pp. 190019
Author(s):  
Amit N. Pujari ◽  
Richard D. Neilson ◽  
Marco Cardinale
Keyword(s):  
Upper Limb ◽  
Isometric Contraction ◽  
Exercise Intervention ◽  
Biceps Brachii ◽  
Whole Body ◽  
Emg Activity ◽  
Isometric Contractions ◽  
Fatigue Development ◽  
Limb Muscles ◽  
Fatiguing Contractions

Whole-body vibration and upper limb vibration (ULV) continue to gain popularity as exercise intervention for rehabilitation and sports applications. However, the fatiguing effects of indirect vibration stimulation are not yet fully understood. We investigated the effects of ULV stimulation superimposed on fatiguing isometric contractions using a purpose developed upper limb stimulation device. Thirteen healthy volunteers were exposed to both ULV superimposed to fatiguing isometric contractions (V) and isometric contractions alone Control (C). Both Vibration (V) and Control (C) exercises were performed at 80% of the maximum voluntary contractions. The stimulation used was 30 Hz frequency of 0.4 mm amplitude. Surface-electromyographic (EMG) activity of the Biceps Brachii, Triceps Brachii and Flexor Carpi Radialis were measured. EMG amplitude (EMGrms) and mean frequency (MEF) were computed to quantify muscle activity and fatigue levels. All muscles displayed significantly higher reduction in MEFs and a corresponding significant increase in EMGrms with the V than the Control, during fatiguing contractions ( p < 0.05). Post vibration, all muscles showed higher levels of MEFs after recovery compared to the control. Our results show that near-maximal isometric fatiguing contractions superimposed on vibration stimulation lead to a higher rate of fatigue development compared to the isometric contraction alone in the upper limb muscles. Results also show higher manifestation of mechanical fatigue post treatment with vibration compared to the control. Vibration superimposed on isometric contraction not only seems to alter the neuromuscular function during fatiguing efforts by inducing higher neuromuscular load but also post vibration treatment.

scholarly journals Fatiguing Effects of Indirect Vibration Stimulation in Upper Limb Muscles- pre, post and during Isometric Contractions Superimposed on Upper Limb Vibration

2018 ◽  
Author(s):  
Amit N. Pujari ◽  
Richard D. Neilson ◽  
Marco Cardinale
Keyword(s):  
Upper Limb ◽  
Isometric Contraction ◽  
Exercise Intervention ◽  
Whole Body ◽  
Emg Activity ◽  
Isometric Contractions ◽  
Vibration Treatment ◽  
Fatigue Development ◽  
Limb Muscles ◽  
Fatiguing Contractions

AbstractBackgroundIndirect vibration stimulation i.e. whole body vibration and upper limb vibration (ULV), are gaining popularity as exercise intervention for sports and rehabilitation applications. However, the fatiguing effects of indirect vibration stimulation are not yet fully understood. In addition, current vibration stimulation devices have a series of limitations. For this scope, we investigated the effects of ULV superimposed on fatiguing graded isometric contractions using a newly, purpose developed upper limb stimulation device. Twelve healthy volunteers were exposed to both ULV superimposed to fatiguing isometric contractions, at 80% of the maximum voluntary contractions (V) and just isometric contractions performed on a custom designed arm curl/flexion device- Control (C). The stimulation used consisted of 30Hz frequency of 0.4mm amplitude. Surface electromyographic (EMG) activity of the Biceps Brachii (BB), Triceps Brachii (TB), and Flexor Carpi Radialis (Forearm- FCR) were measured during both V and C conditions. EMG amplitude (EMGrms) and mean frequency (MEF) were computed to quantify muscle activity and fatigue levels respectively.ResultsAll three muscles BB, TB and FCR displayed significantly higher reduction in MEFs and corresponding significant increase in EMGrms with the V than the C, during fatiguing contractions (P < 0.05). Post vibration treatment, all muscles showed higher levels of MEFs after recovery compared to the control.ConclusionsOur results show that near maximal (80% of MVC) isometric fatiguing contractions superimposed on vibration stimulation lead to a higher rate of fatigue development compared to the isometric contraction alone in the upper limb muscles. Results also show, higher manifestation of mechanical fatigue post treatment with vibration compared to the control. Vibration superimposed on isometric contraction not only seems to alter the neuromuscular function during fatiguing efforts by inducing higher neuromuscular load but also post vibration treatment, potentially through the augmentation of stretch reflex and/or higher central motor command excitability.

Cortical Control of Human Motoneuron Firing During Isometric Contraction

1997 ◽  
Vol 77 (6) ◽  
pp. 3401-3405 ◽  
Author(s):  
Stephan Salenius ◽  
Karin Portin ◽  
Matti Kajola ◽  
Riitta Salmelin ◽  
Riitta Hari
Keyword(s):  
Motor Cortex ◽  
Upper Limb ◽  
Isometric Contraction ◽  
Lower Limb ◽  
Biceps Brachii ◽  
Cortical Control ◽  
Lower Limb Muscles ◽  
Cortical Rhythms ◽  
Motor Unit Firing ◽  
Limb Muscles

Salenius, Stephan, Karin Portin, Matti Kajola, Riitta Salmelin, and Riitta Hari. Cortical control of human motoneuron firing during isometric contraction. J. Neurophysiol. 77: 3401–3405, 1997. We recorded whole scalp magnetoencephalographic (MEG) signals simultaneously with the surface electromyogram from upper and lower limb muscles of six healthy right-handed adults during voluntary isometric contraction. The 15- to 33-Hz MEG signals, originating from the anterior bank of the central sulcus, i.e., the primary motor cortex, were coherent with motor unit firing in all subjects and for all muscles. The coherent cortical rhythms originated in the hand motor area for upper limb muscles (1st dorsal interosseus, extensor indicis proprius, and biceps brachii) and close to the foot area for lower limb muscles (flexor hallucis brevis). The sites of origin corresponding to different upper limb muscles did not differ significantly. The cortical signals preceded motor unit firing by 12–53 ms. The lags were shortest for the biceps brachii and increased systematically with increasing corticomuscular distance. We suggest that the motor cortex drives the spinal motoneuronal pool during sustained contractions, with the observed cortical rhythmic activity influencing the timing of efferent commands. The cortical rhythms could be related to motor binding, but the rhythmic output may also serve to optimize motor cortex output during isometric contractions.

scholarly journals The Effects of Different Vibration Frequencies, Amplitudes and Contraction Levels on Lower Limb Muscles during Graded Isometric Contractions Superimposed on Whole Body Vibration Stimulation

2018 ◽  
Author(s):  
Amit N. Pujari ◽  
Richard D. Neilson ◽  
Marco Cardinale
Keyword(s):  
Muscle Contraction ◽  
Isometric Contraction ◽  
Whole Body Vibration ◽  
Lower Limbs ◽  
Whole Body ◽  
Emg Activity ◽  
Isometric Contractions ◽  
Body Vibration ◽  
Neuromuscular Activity ◽  
Co Activation

AbstractBackgroundIndirect vibration stimulation i.e. whole body vibration or upper limb vibration, has been suggested increasingly as an effective exercise intervention for sports and rehabilitation applications. However, there is a lack of evidence regarding the effects of whole body vibration (WBV) stimulation superimposed to graded isometric contractions superimposed on. For this scope, we investigated the effects of WBV superimposed to graded isometric contractions in the lower limbs on muscle activation. We also assessed the agonist-antagonist co-activation during this type of exercise.Twelve healthy volunteers were exposed to WBV superimposed to graded isometric contractions, at 20, 40, 60, 80 and 100% of the maximum voluntary contractions (V) or just isometric contractions performed on a custom designed horizontal leg press Control (C). Tested stimulation consisted of 30Hzand 50Hz frequencies and 0.5mm and 1.5mm amplitudes. Surface electromyographic activity of Vastus Lateralis (VL), Vastus Medialis (VM) and Biceps Femoris (BF) were measured during V and C conditions. Co-contraction activity of agonist-antagonist muscles was also quantified. The trials were performed in random order.ResultsBoth the prime mover, (VL) and the antagonist, (BF) displayed significantly higher (P < 0.05) EMG activity with the V than the C condition. For both the VL and BF, the increase in mean EMGrms values depended on the frequency, amplitude and muscle contraction level with 50Hz-0.5mm stimulation inducing the largest neuromuscular activity. 50Hz-0.5mm V condition also led to co-activation ratios significantly (P< 0.05) higher at 40, 80 and 100% of MVC than the C condition.ConclusionsOur results show that the isometric contraction superimposed on vibration stimulation leads to higher neuromuscular activity compared to isometric contraction alone in the lower limbs. Compared to the control condition, the vibratory stimulation leads to higher agonist-antagonist co-activation of the muscles around the knee joint in all vibration conditions and effort levels. The combination of vibration magnitude (frequency and amplitude) and the level of muscle contraction affect neuromuscular activity rather than vibration frequency alone. Results of this study suggest that more parameters need to be taken into consideration when designing vibration exercise programs for sports and rehabilitation purposes.

scholarly journals High-density surface electromyography signals during isometric contractions of elbow muscles of healthy humans

2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Mónica Rojas-Martínez ◽  
Leidy Yanet Serna ◽  
Mislav Jordanic ◽  
Hamid Reza Marateb ◽  
Roberto Merletti ◽  
...  
Keyword(s):  
Upper Limb ◽  
Biceps Brachii ◽  
High Density ◽  
Isometric Contractions ◽  
Myoelectric Activity ◽  
Electrode Arrays ◽  
Triceps Brachii ◽  
Healthy Humans ◽  
Limb Muscles ◽  
Density Surface

AbstractThis paper presents a dataset of high-density surface EMG signals (HD-sEMG) designed to study patterns of sEMG spatial distribution over upper limb muscles during voluntary isometric contractions. Twelve healthy subjects performed four different isometric tasks at different effort levels associated with movements of the forearm. Three 2-D electrode arrays were used for recording the myoelectric activity from five upper limb muscles: biceps brachii, triceps brachii, anconeus, brachioradialis, and pronator teres. Technical validation comprised a signals quality assessment from outlier detection algorithms based on supervised and non-supervised classification methods. About 6% of the total number of signals were identified as “bad” channels demonstrating the high quality of the recordings. In addition, spatial and intensity features of HD-sEMG maps for identification of effort type and level, have been formulated in the framework of this database, demonstrating better performance than the traditional time-domain features. The presented database can be used for pattern recognition and MUAP identification among other uses.

Effects of Leg Pedaling on Early Latency Cutaneous Reflexes in Upper Limb Muscles

2010 ◽  
Vol 104 (1) ◽  
pp. 210-217 ◽  
Author(s):  
Syusaku Sasada ◽  
Toshiki Tazoe ◽  
Tsuyoshi Nakajima ◽  
E. Paul Zehr ◽  
Tomoyoshi Komiyama
Keyword(s):  
Upper Limb ◽  
Biceps Brachii ◽  
Lower Limbs ◽  
Functional Coupling ◽  
Isometric Contractions ◽  
Rhythmic Movements ◽  
Discrete Movements ◽  
Cutaneous Reflex ◽  
Limb Muscles ◽  
Control Research

The functional coupling of neural circuits between the upper and lower limbs involving rhythmic movements is of interest to both motor control research and rehabilitation science. This coupling can be detected by examining the effect of remote rhythmic limb movement on the modulation of reflex amplitude in stationary limbs. The present study investigated the extent to which rhythmic leg pedaling modulates the amplitude of an early latency (peak 30–70 ms) cutaneous reflex (ELCR) in the upper limb muscles. Thirteen neurologically intact volunteers performed leg pedaling (60 or 90 rpm) while simultaneously contracting their arm muscles isometrically. Control experiments included isolated isometric contractions and discrete movements of the leg. ELCRs were evoked by stimulation of the superficial radial nerve with a train of rectangular pulses (three pulses at 333 Hz, intensity 2.0- to 2.5-fold perceptual threshold). Reflex amplitudes were significantly increased in the flexor carpi radialis and posterior deltoid and significantly decreased in the biceps brachii muscles during leg pedaling compared with that during stationary isometric contraction of the lower leg muscles. This effect was also sensitive to cadence. No significant modulation was seen during the isometric contractions or discrete movements of the leg. Additionally, there was no phase-dependent modulation of the ELCR. These findings suggest that activation of the rhythm generating system of the legs affects the excitability of the early latency cutaneous reflex pathways in the upper limbs.

Influence of submaximal isometric contractions of the hamstrings on electromyography activity and force while functioning as hip extensors

2020 ◽  
pp. 1-8
Author(s):  
Dasom Oh ◽  
Wootaek Lim
Keyword(s):  
Prone Position ◽  
Supine Position ◽  
Isometric Contraction ◽  
Muscle Length ◽  
Biceps Femoris ◽  
Emg Activity ◽  
Isometric Contractions ◽  
Significant Difference ◽  
Extension Force ◽  
Long Head

BACKGROUND: Although the medial and lateral hamstrings are clearly distinct anatomically and have different functions in the transverse plane, they are often considered as one muscle during rehabilitation. OBJECTIVE: The purpose of the study was to compare the electromyographic (EMG) activity between the prone position and the supine position during maximal isometric contraction and to additionally confirm the effect of submaximal isometric contractions on EMG activity of medial and lateral hamstrings, and force. METHODS: In the prone position, EMG activities of the long head of biceps femoris (BFLH) and semitendinosus (ST) were measured during the maximal isometric contraction. In the supine position, hip extension force with EMG activity were measured during the maximal and the submaximal isometric contractions. RESULTS: EMG activity in the prone position was significantly decreased in the supine position. In the supine position, there was a significant difference between the BFLH and ST during the maximal isometric contraction, but not during the submaximal isometric contractions. CONCLUSIONS: The dependence on the hamstrings could be relatively lower during hip extensions. When the medial and lateral hamstrings are considered separately, the lateral hamstrings may show a more active response, with increased muscle length, in clinical practice.

scholarly journals Effects of different vibration frequencies, amplitudes and contraction levels on lower limb muscles during graded isometric contractions superimposed on whole body vibration stimulation

2019 ◽  
Vol 6 ◽  
pp. 205566831982746 ◽  
Author(s):  
Amit N Pujari ◽  
Richard D Neilson ◽  
Marco Cardinale
Keyword(s):  
Isometric Contraction ◽  
Vastus Lateralis ◽  
Whole Body Vibration ◽  
Biceps Femoris ◽  
Whole Body ◽  
Isometric Contractions ◽  
Electromyographic Activity ◽  
Mean Square ◽  
Body Vibration ◽  
Neuromuscular Activity

Background Indirect vibration stimulation, i.e., whole body vibration or upper limb vibration, has been investigated increasingly as an exercise intervention for rehabilitation applications. However, there is a lack of evidence regarding the effects of graded isometric contractions superimposed on whole body vibration stimulation. Hence, the objective of this study was to quantify and analyse the effects of variations in the vibration parameters and contraction levels on the neuromuscular responses to isometric exercise superimposed on whole body vibration stimulation. Methods In this study, we assessed the ‘neuromuscular effects’ of graded isometric contractions, of 20%, 40%, 60%, 80% and 100% of maximum voluntary contraction, superimposed on whole body vibration stimulation (V) and control (C), i.e., no-vibration in 12 healthy volunteers. Vibration stimuli tested were 30 Hz and 50 Hz frequencies and 0.5 mm and 1.5 mm amplitude. Surface electromyographic activity of the vastus lateralis, vastus medialis and biceps femoris were measured during V and C conditions with electromyographic root mean square and electromyographic mean frequency values used to quantify muscle activity and their fatigue levels, respectively. Results Both the prime mover (vastus lateralis) and the antagonist (biceps femoris) displayed significantly higher (P < 0.05) electromyographic activity with the V than the C condition with varying percentage increases in EMG root-mean-square (EMGrms) values ranging from 20% to 200%. For both the vastus lateralis and biceps femoris, the increase in mean EMGrms values depended on the frequency, amplitude and muscle contraction level with 50 Hz–0.5 mm stimulation inducing the largest neuromuscular activity. Conclusions These results show that the isometric contraction superimposed on vibration stimulation leads to higher neuromuscular activity compared to isometric contraction alone in the lower limbs. The combination of the vibration frequency with the amplitude and the muscle tension together grades the final neuromuscular output.

scholarly journals Effects of Focal Vibration over Upper Limb Muscles on the Activation of Sensorimotor Cortex Network: An EEG Study

2019 ◽  
Vol 2019 ◽  
pp. 1-7 ◽  
Author(s):  
Wei Li ◽  
Chong Li ◽  
Quan Xu ◽  
Linhong Ji
Keyword(s):  
Upper Limb ◽  
Sensorimotor Cortex ◽  
Biceps Brachii ◽  
Central Area ◽  
Therapeutic Effects ◽  
Relative Power ◽  
Alpha Band ◽  
Beta Band ◽  
Muscle Belly ◽  
Limb Muscles

Studying the therapeutic effects of focal vibration (FV) in neurorehabilitation is the focus of current research. However, it is still not fully understood how FV on upper limb muscles affects the sensorimotor cortex in healthy subjects. To explore this problem, this experiment was designed and conducted, in which FV was applied to the muscle belly of biceps brachii in the left arm. During the experiment, electroencephalography (EEG) was recorded in the following three phases: before FV, during FV, and two minutes after FV. During FV, a significant lower relative power at C3 and C4 electrodes and a significant higher connection strength between five channel pairs (Cz-FC1, Cz-C3, Cz-CP6, C4-FC6, and FC6-CP2) in the alpha band were observed compared to those before FV. After FV, the relative power at C4 in the beta band showed a significant increase compared to its value before FV. The changes of the relative power at C4 in the alpha band had a negative correlation with the relative power of the beta band during FV and with that after FV. The results showed that FV on upper limb muscles could activate the bilateral primary somatosensory cortex and strengthen functional connectivity of the ipsilateral central area (FC1, C3, and Cz) and contralateral central area (CP2, Cz, C4, FC6, and CP6). These results contribute to understanding the effect of FV over upper limb muscles on the brain cortical network.

Heteronymous reflex connections in human upper limb muscles in response to stretch of forearm muscles

2011 ◽  
Vol 106 (3) ◽  
pp. 1489-1499 ◽  
Author(s):  
Curtis D. Manning ◽  
Parveen Bawa
Keyword(s):  
Upper Limb ◽  
Biceps Brachii ◽  
Monosynaptic Reflex ◽  
Electromyographic Activity ◽  
Response Patterns ◽  
Triceps Brachii ◽  
Limb Muscles ◽  
Abductor Digiti Minimi ◽  
Human Upper Limb ◽  
Wrist Flexors

Torque motor produced stretch of upper limb muscles results in two distinct reflex peaks in the electromyographic activity. Whereas the short-latency reflex (SLR) response is mediated largely by the spinal monosynaptic reflex pathway, the longer-latency reflex (LLR) is suggested to involve a transcortical loop. For the SLRs, patterns of heteronymous monosynaptic Ia connections have been well-studied for a large number of muscles in the cat and in humans. For LLRs, information is available for perturbations to proximal joints, although the protocols for most of these studies did not focus on heteronymous connections. The main objective of the present study was to elicit both SLRs and LLRs in wrist flexors and extensors and to examine heteronymous connections from these muscles to elbow flexors (biceps brachii; BiBr) and extensors (triceps brachii; TriBr) and to selected distal muscles, including abductor pollicis longus (APL), first dorsal interosseous (FDI), abductor digiti minimi (ADM), and Thenars. The stretch of wrist flexors produced SLR and LLR peaks in APL, FDI, ADM, Thenars, and BiBr while simultaneously inducing inhibition of wrist extensors and TriBr. When wrist extensors were stretched, SLR and LLR peaks were observed in TriBr, whereas the primary wrist flexors, APL and BiBr, were inhibited; response patterns of FDI, ADM, and Thenars were less consistent. The main conclusions from the observed data are that: 1) as in the cat, afferents from wrist flexors and extensors make heteronymous connections with proximal and distal upper limb muscles; and 2) the strength of heteronymous connections is greater for LLRs than SLRs in the distal muscles, whereas the opposite is true for the proximal muscles. In the majority of observations, SLR and LLR excitatory peaks were observed together. However, on occasion, LLRs were observed without the SLR response in hand muscles when wrist extensors were stretched.

scholarly journals Modulation of Stretch Reflexes of the Finger Flexors by Sensory Feedback From the Proximal Upper Limb Poststroke

2009 ◽  
Vol 102 (3) ◽  
pp. 1420-1429 ◽  
Author(s):  
Gilles Hoffmann ◽  
Derek G. Kamper ◽  
Jennifer H. Kahn ◽  
William Z. Rymer ◽  
Brian D. Schmit
Keyword(s):  
Upper Limb ◽  
Stretch Reflex ◽  
Sensory Input ◽  
Biceps Brachii ◽  
Elbow Flexion ◽  
Spinal Reflex ◽  
Reflex Response ◽  
Emg Activity ◽  
Triceps Brachii ◽  
Flexor Digitorum

Neural coupling of proximal and distal upper limb segments may have functional implications in the recovery of hemiparesis after stroke. The goal of the present study was to investigate whether the stretch reflex response magnitude of spastic finger flexor muscles poststroke is influenced by sensory input from the shoulder and the elbow and whether reflex coupling of muscles throughout the upper limb is altered in spastic stroke survivors. Through imposed extension of the metacarpophalangeal (MCP) joints, stretch of the relaxed finger flexors of the four fingers was imposed in 10 relaxed stroke subjects under different conditions of proximal sensory input, namely static arm posture (3 different shoulder/elbow postures) and electrical stimulation (surface stimulation of biceps brachii or triceps brachii, or none). Fast (300°/s) imposed stretch elicited stretch reflex flexion torque at the MCP joints and reflex electromyographic (EMG) activity in flexor digitorum superficialis. Both measures were greatest in an arm posture of 90° of elbow flexion and neutral shoulder position. Biceps stimulation resulted in greater MCP stretch reflex flexion torque. Fast imposed stretch also elicited reflex EMG activity in nonstretched heteronymous upper limb muscles, both proximal and distal. These results suggest that in the spastic hemiparetic upper limb poststroke, sensorimotor coupling of proximal and distal upper limb segments is involved in both the increased stretch reflex response of the finger flexors and an increased reflex coupling of heteronymous muscles. Both phenomena may be mediated through changes poststroke in the spinal reflex circuits and/or in the descending influence of supraspinal pathways.

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