scholarly journals Spatial Intensity Map of HDEMG Based Classification of Muscle Fatigue

2021 ◽  
Author(s):  
Navaneethakrishna Makaram ◽  
Sridhar P. Arjunan ◽  
Dinesh Kumar ◽  
Ramakrishnan Swaminathan
Keyword(s):  
Muscle Fatigue ◽  
Tibialis Anterior ◽  
Plantar Flexion ◽  
Tibialis Anterior Muscle ◽  
Maximum Voluntary Contraction ◽  
Real Life ◽  
Voluntary Contraction ◽  
Spatial Intensity ◽  
Intensity Map

In this, study, we have investigated to identify the muscle fatigue using spatial maps of High-Density Electromyography (HDEMG). The experiment involves subjects performing plantar flexion at 40% maximum voluntary contraction until fatigue. During the experiment, HDEMG signal was recorded from the tibialis anterior muscle. The monopolar and bipolar spatial intensity maps were extracted from the HDEMG signal. The random forest classifier with different tree configurations was tested to distinguish nonfatigue and fatigue condition. The results indicate that selected electrodes from the differential intensity map results in an accuracy of 83.3% with the number of trees set at 17. This method of spatial analysis of HDEMG signals may be extended to assess fatigue in real life scenarios.

Muscle fatigue-induced enhancement of corticomuscular coherence following sustained submaximal isometric contraction of the tibialis anterior muscle

2011 ◽  
Vol 110 (5) ◽  
pp. 1233-1240 ◽  
Author(s):  
Junichi Ushiyama ◽  
Masanori Katsu ◽  
Yoshihisa Masakado ◽  
Akio Kimura ◽  
Meigen Liu ◽  
...  
Keyword(s):  
Muscle Fatigue ◽  
Isometric Contraction ◽  
Sensorimotor Cortex ◽  
Tibialis Anterior ◽  
Tibialis Anterior Muscle ◽  
Muscular Activity ◽  
Spectral Density Function ◽  
Voluntary Contraction ◽  
Oscillatory Activity ◽  
Acute Changes

Oscillatory activity of the sensorimotor cortex shows coherence with muscle activity within the 15- to 35-Hz frequency band (β-band) during weak to moderate sustained isometric contraction. We aimed to examine the acute changes in this corticomuscular coupling due to muscle fatigue and its effect on the steadiness of the exerted force. We quantified the coherence between the electroencephalogram (EEG) recorded over the sensorimotor cortex and the rectified surface electromyogram (EMG) of the tibialis anterior muscle as well as the coefficient of variance of the dorsiflexion force (ForceCV) and sum of the auto-power spectral density function of the force within the β-band (Forceβ-PSD) during 30% of maximal voluntary contraction (MVC) for 60 s before (prefatiguing task) and after (postfatiguing task) muscle fatigue induced by sustained isometric contraction at 50% of MVC until exhaustion in seven healthy male subjects. The magnitude of the EEG-EMG coherence increased in the postfatiguing task in six of seven subjects. The maximal peak of EEG-EMG coherence stayed within the β-band in both pre- and postfatiguing tasks. Interestingly, two subjects, who had no significant EEG-EMG coherence in the prefatiguing task, showed significant coherence in the postfatiguing task. Additionally, ForceCV and Forceβ-PSD significantly increased after muscle fatigue. These data suggest that when muscle fatigue develops, the central nervous system enhances oscillatory muscular activity in the β-band stronger coupled with the sensorimotor cortex activity accomplishing the sustained isometric contraction at lower performance levels.

Changes in muscle fiber conduction velocity indicate recruitment of distinct motor unit populations

2003 ◽  
Vol 95 (3) ◽  
pp. 1045-1054 ◽  
Author(s):  
C. J. Houtman ◽  
D. F. Stegeman ◽  
J. P. Van Dijk ◽  
M. J. Zwarts
Keyword(s):  
Conduction Velocity ◽  
Muscle Fiber ◽  
Tibialis Anterior Muscle ◽  
Maximum Voluntary Contraction ◽  
Isometric Exercise ◽  
Motor Units ◽  
Voluntary Contraction ◽  
Type I ◽  
Muscle Fiber Conduction Velocity ◽  
Depth Study

To obtain more insight into the changes in mean muscle fiber conduction velocity (MFCV) during sustained isometric exercise at relatively low contraction levels, we performed an in-depth study of the human tibialis anterior muscle by using multichannel surface electromyogram. The results show an increase in MFCV after an initial decrease of MFCV at 30 or 40% maximum voluntary contraction in all of the five subjects studied. With a peak velocity analysis, we calculated the distribution of conduction velocities of action potentials in the bipolar electromyogram signal. It shows two populations of peak velocities occurring simultaneously halfway through the exercise. The MFCV pattern implies the recruitment of two different populations of motor units. Because of the lowering of MFCV of the first activated population of motor units, the newly recruited second population of motor units becomes visible. It is most likely that the MFCV pattern can be ascribed to the fatiguing of already recruited predominantly type I motor units, followed by the recruitment of fresh, predominantly type II, motor units.

Pain-induced changes in motor unit discharge depend on recruitment threshold and contraction speed

2021 ◽  
Author(s):  
Eduardo Martinez-Valdes ◽  
Francesco Negro ◽  
Michail Arvanitidis ◽  
Dario Farina ◽  
Deborah Falla
Keyword(s):  
Discharge Rate ◽  
Tibialis Anterior Muscle ◽  
Maximum Voluntary Contraction ◽  
Motor Units ◽  
Inhibitory Effect ◽  
Voluntary Contraction ◽  
Recruitment Threshold ◽  
Contraction Speed ◽  
Discharge Rates ◽  
Hypertonic Saline Injection

At high forces, the discharge rates of lower and higher threshold motor units (MU) are influenced in a different way by muscle pain. These differential effects may be particularly important for performing contractions at different speeds since the proportion of lower and higher threshold MUs recruited varies with contraction velocity. We investigated whether MU discharge and recruitment strategies are differentially affected by pain depending on their recruitment threshold (RT), across a range of contraction speeds. Participants performed ankle dorsiflexion sinusoidal-isometric contractions at two frequencies (0.25Hz and 1Hz) and two modulation amplitudes [5% and 10% of the maximum voluntary contraction (MVC)] with a mean target torque of 20%MVC. High-density surface electromyography recordings from the tibialis anterior muscle were decomposed and the same MUs were tracked across painful (hypertonic saline injection) and non-painful conditions. Torque variability, mean discharge rate (MDR), DR variability (DRvar), RT and the delay between the cumulative spike train and the resultant torque output (neuromechanical delay, NMD) were assessed. The average RT was greater at faster contraction velocities (p=0.01) but was not affected by pain. At the fastest contraction speed, torque variability and DRvar were reduced (p<0.05) and MDR was maintained. Conversely, MDR decreased and DRvar and NMD increased significantly during pain at slow contraction speeds (p<0.05). These results show that reductions in contraction amplitude and increased recruitment of higher threshold MUs at fast contraction speeds appears to compensate for the inhibitory effect of nociceptive inputs on lower threshold MUs, allowing the exertion of fast submaximal contractions during pain.

13C-NMR measurements of muscle glycogen during low-intensity exercise

1991 ◽  
Vol 70 (4) ◽  
pp. 1836-1844 ◽  
Author(s):  
T. B. Price ◽  
D. L. Rothman ◽  
M. J. Avison ◽  
P. Buonamico ◽  
R. G. Shulman
Keyword(s):  
Steady State ◽  
13C Nmr ◽  
Muscle Glycogen ◽  
Plantar Flexion ◽  
Maximum Voluntary Contraction ◽  
Blood Velocity ◽  
Voluntary Contraction ◽  
Low Intensity ◽  
13C Nuclear Magnetic Resonance ◽  
Low Intensity Exercise

Glycogen metabolism in exercising gastrocnemius muscles was examined by natural abundance 13C nuclear magnetic resonance (NMR) spectroscopy. Five-minute 13C-NMR measurement of muscle glycogen had a reproducibility of +/- 6.5% (+/- 4.8 mM). Experiments were performed on healthy fed male and female subjects. Two protocols were followed. 1) Subjects performed plantar flexion from rest at 15, 20, or 25% of maximum voluntary contraction for up to 9 h. 2) Subjects predepleted gastrocnemius glycogen with heavy exercise and then either performed low-intensity exercise as before or rested. Gastrocnemius glycogen was measured by NMR at rest and after each hour of exercise. In some sessions, both the exercised leg and the nonexercised leg were monitored with 13C-NMR. In protocol 1, blood velocity in the femoral artery was similarly assessed with ultrasonography. During low-intensity exercise from rest (protocol 1) muscle glycogen fell to a new steady-state value after several hours and then remained constant despite continued exercise. Mean blood velocity increased ninefold within 2 min of onset of exercise and remained constant thereafter. After predepletion (protocol 2), muscle glycogen was repleted both during low-intensity exercise and at rest. After 1 h the amount of glycogen repletion was greater when coupled with light exercise [48.5 +/- 2.8 mM after 1 h of exercise, 39.7 +/- 1.1 mM after 1 h of rest (P less than 0.05)]. During subsequent light exercise, glycogen reached a steady-state value similar to that obtained in protocol 1, while in resting, recovery glycogen levels continued to increase (+2.7 mM/h) over a 7-h period.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Operant Up-Conditioning of the Tibialis Anterior Motor-Evoked Potential in Multiple Sclerosis: Feasibility Case Studies

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Aiko K. Thompson ◽  
Briana M. Favale ◽  
Jacqueline Velez ◽  
Patricia Falivena
Keyword(s):  
Multiple Sclerosis ◽  
Operant Conditioning ◽  
Tibialis Anterior ◽  
Evoked Potential ◽  
Maximum Voluntary Contraction ◽  
Motor Evoked Potential ◽  
Voluntary Contraction ◽  
Foot Drop ◽  
Immediate Feedback ◽  
Cord Injury

Damage to the corticospinal pathway often results in weak dorsiflexion of the ankle, thereby limiting the mobility of people with multiple sclerosis (MS). Thus, strengthening corticospinal connectivity may improve locomotion. Here, we investigated the feasibility of tibialis anterior (TA) motor-evoked potential (MEP) operant conditioning and whether it can enhance corticospinal excitability and alleviate locomotor problems in people with chronic stable MS. The protocol consisted of 6 baseline and 24 up-conditioning sessions over 10 weeks. In all sessions, TA MEPs were elicited at 10% above active threshold while the sitting subject provided 30–35% maximum voluntary contraction (MVC) level of TA background EMG. During baseline sessions, MEPs were simply measured. During conditioning trials of the conditioning sessions, the subject was encouraged to increase MEP and was given immediate feedback indicating whether MEP size was above a criterion. In 3/4 subjects, TA MEP increased 32–75%, MVC increased 28–52%, locomotor EMG modulation improved in multiple leg muscles, and foot drop became less severe. In one of them, MEP and MVC increases were maintained throughout 3 years of extensive follow-up sessions. These initial results support a therapeutic possibility of MEP operant conditioning for improving locomotion in people with MS or other CNS disorders, such as spinal cord injury and stroke.

scholarly journals Effects of force level and task difficulty on force control performance in elderly people

2020 ◽  
Vol 238 (10) ◽  
pp. 2179-2188
Author(s):  
Caren Strote ◽  
Christian Gölz ◽  
Julia Kristin Stroehlein ◽  
Franziska Katharina Haase ◽  
Dirk Koester ◽  
...  
Keyword(s):  
Elderly People ◽  
Force Control ◽  
Task Difficulty ◽  
Negative Impact ◽  
Maximum Voluntary Contraction ◽  
Real Life ◽  
Voluntary Contraction ◽  
Fine Motor ◽  
Force Level ◽  
Control Performance

Abstract As the proportion of people over 60 years of age rises continuously in westernized societies, it becomes increasingly important to better understand aging processes and how to maintain independence in old age. Fine motor tasks are essential in daily living and, therefore, necessary to maintain. This paper extends the existing literature on fine motor control by manipulating the difficulty of a force maintenance task to characterize performance optima for elderly. Thirty-seven elderly (M = 68.00, SD = 4.65) performed a force control task at dynamically varying force levels, i.e. randomly changing every 3 s between 10%, 20%, and 30% of the individual’s maximum voluntary contraction (MVC). This task was performed alone or with one or two additional tasks to increase task difficulty. The force control characteristics accuracy, variability, and complexity were analyzed. Lowest variability was observed at 20%. Accuracy and complexity increased with increasing force level. Overall, increased task difficulty had a negative impact on task performance. Results support the assumption, that attention control has a major impact on force control performance in elderly people. We assume different parameters to have their optimum at different force levels, which remain comparably stable when additional tasks are performed. The study contributes to a better understanding of how force control is affected in real-life situations when it is performed simultaneously to other cognitive and sensory active and passive tasks.

Achilles Tendon Mechanical Properties After Both Prolonged Continuous Running and Prolonged Intermittent Shuttle Running in Cricket Batting

2013 ◽  
Vol 29 (4) ◽  
pp. 453-462 ◽  
Author(s):  
Laurence Houghton ◽  
Brian Dawson ◽  
Jonas Rubenson
Keyword(s):  
Achilles Tendon ◽  
Elastic Energy ◽  
Plantar Flexion ◽  
Maximum Voluntary Contraction ◽  
Voluntary Contraction ◽  
Force Transmission ◽  
Before And After ◽  
Tendon Force ◽  
Force Displacement ◽  
Tendon Properties

Effects of prolonged running on Achilles tendon properties were assessed after a 60 min treadmill run and 140 min intermittent shuttle running (simulated cricket batting innings). Before and after exercise, 11 participants performed ramp-up plantar flexions to maximum-voluntary-contraction before gradual relaxation. Muscle-tendon-junction displacement was measured with ultrasonography. Tendon force was estimated using dynamometry and a musculoskeletal model. Gradients of the ramp-up force-displacement curves fitted between 0–40% and 50–90% of the preexercise maximal force determined stiffness in the low- and high-force-range, respectively. Hysteresis was determined using the ramp-up and relaxation force-displacement curves and elastic energy storage from the area under the ramp-up curve. In simulated batting, correlations between tendon properties and shuttle times were also assessed. After both protocols, Achilles tendon force decreased (4% to 5%,P< .050), but there were no changes in stiffness, hysteresis, or elastic energy. In simulated batting, Achilles tendon force and stiffness were both correlated to mean turn and mean sprint times (r= −0.719 to −0.830,P< .050). Neither protocol resulted in fatigue-related changes in tendon properties, but higher tendon stiffness and plantar flexion force were related to faster turn and sprint times, possibly by improving force transmission and control of movement when decelerating and accelerating.

scholarly journals Comparing neck extensor muscle function in asymptomatic Canadian adults and adults with tension-type headache: a cross-sectional study

BMJ Open ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. e020984 ◽  
Author(s):  
Andrée-Anne Marchand ◽  
Mariève Houle ◽  
Marie-Pier Girard ◽  
Marie-Ève Hébert ◽  
Martin Descarreaux
Keyword(s):  
Muscle Fatigue ◽  
Maximum Voluntary Contraction ◽  
Tension Type Headache ◽  
Voluntary Contraction ◽  
Extensor Muscle ◽  
Control Group ◽  
Physical Parameters ◽  
Cross Sectional ◽  
Neck Extension ◽  
Type Headache

AimTo further the understanding of the pathophysiological mechanisms underlying tension-type headache (TTH) by comparing the endurance and strength of neck extensor muscles under acute muscle fatigue in participants with TTH and asymptomatic participants.MethodsWe conducted a cross-sectional analysis of neck extensor muscle performance. Asymptomatic participants and participants with TTH were recruited via social media platforms and from the Université du Québec à Trois-Rivières community and employees. A total of 44 participants with TTH and 40 asymptomatic participants took part in an isometric neck extensor endurance task performed at 60% of their maximum voluntary contraction. Inclusion criteria for the headache group were to be older than 18 years old and to fulfil the International Headache Society classification’s criteria for either frequent episodic or chronic TTH. Clinical (self-efficacy, anxiety, neck disability and kinesiophobia) and physical parameters (neck extensors maximum voluntary contraction, endurance time, muscle fatigue) as well as characteristics of headache episodes (intensity, frequency and associated disability) were collected for all participants. Surface electromyography was used to document upper trapezius, splenius capitis and sternocleidomastoids muscle activity and muscle fatigue.ResultsBoth groups displayed similar neck extensor muscle endurance capacity with a mean difference of 6.2 s (p>0.05) in favour of the control group (control=68.1±32.3; TTH=61.9±20.1). Similarly, participants in the headache group showed comparable neck extensor muscle strength (95.9±30.4 N) to the control group (111.3±38.7 N). Among participants with TTH, those scoring as severely incapacitated by headaches were the ones with higher neck-related disability (F[1,44]=10.77; p=0.002), the more frequent headache episodes (F[1,44]=6.70; p=0.01) and higher maximum headache intensity (F[1,44]=10.81; p=0.002).ConclusionA fatigue task consisting of isometric neck extension cannot efficiently differentiate participants with TTH from asymptomatic participants.

Sign in / Sign up

Export Citation Format

Share Document