Assessing the Therapeutic Effect of 630 nm Light-emitting Diodes Irradiation on the Recovery of Exercise-induced Hand Muscle Fatigue with Surface Electromyogram

This paper aims to investigate the effect of light emitting diode therapy (LEDT) on exercise-induced hand muscle fatigue by measuring the surface electromyography (sEMG) of flexor digitorum superficialis. Ten healthy volunteers were randomly placed in the equal sized LEDT group and control group. All subjects performed a sustained fatiguing isometric contraction with the combination of four fingertips except thumb at 30% of maximal voluntary contraction (MVC) until exhaustion. The active LEDT or an identical passive rest therapy was then applied to flexor digitorum superficialis. Each subject was required to perform a re-fatigue task immediately after therapy which was the same as the pre-fatigue task. Average rectified value (ARV) and fractal dimension (FD) of sEMG were calculated. ARV and FD were significantly different between active LEDT and passive rest groups at 20%–50%, 70%–80%, and 100% of normalized contraction time (P \u3c 0.05 ). Compared to passive rest, active LEDT induced significantly smaller increase in ARV values and decrease in FD values, which shows that LEDT is effective on the recovery of muscle fatigue. Our preliminary results also suggest that ARV and FD are potential replacements of biochemical markers to assess the effects of LEDT on muscle fatigue

A Review of Non-Invasive Techniques to Detect and Predict Localised Muscle Fatigue

Muscle fatigue is an established area of research and various types of muscle fatigue have been investigated in order to fully understand the condition. This paper gives an overview of the various non-invasive techniques available for use in automated fatigue detection, such as mechanomyography, electromyography, near-infrared spectroscopy and ultrasound for both isometric and non-isometric contractions. Various signal analysis methods are compared by illustrating their applicability in real-time settings. This paper will be of interest to researchers who wish to select the most appropriate methodology for research on muscle fatigue detection or prediction, or for the development of devices that can be used in, e.g., sports scenarios to improve performance or prevent injury. To date, research on localised muscle fatigue focuses mainly on the clinical side. There is very little research carried out on the implementation of detecting/predicting fatigue using an autonomous system, although recent research on automating the process of localised muscle fatigue detection/prediction shows promising results

Evaluation of performance fatigability through surface EMG in health and muscle disease: state of the art

In literature, it is commonly reported that the progress of performance fatigability may be indirectly assessed through the changes in the features of the surface electromyogram (sEMG) signal. In particular, during isometric constant force contractions, changes in the sEMG signal are caused by several physiological factors, such as a decay in muscle fibers conduction velocity (CV), an increase of the degree of synchronization between the firing times of simultaneously active motor units (MUs), by the central nervous system, and a reduction of the recruitment threshold and a modulation of MUs firing rate. Amplitude and spectral parameters may be used to characterize the global contributions to performance fatigability, such as MU control properties and fiber membrane properties, or central and peripheral factors, respectively. In addition, being CV a physiological parameter, its estimation is of marked interest to the study of fatigue both in physiological and in presence of neuromuscular diseases

Muscle Fatigue at the End of a Maximal Oxygen Consumption Test

Fatigue is a task dependent multifactorial phenomenon, and the most common tool to analyze it is the VO2max test. The purpose of this study was to investigate if muscle is exhaustively taxed at the end of a VO2max test. This was based on data from sEMG, heart rate, and force applied to the pedals during and immediately after a VO2max test compared to an intense anaerobic test. Methods. 12 male participants (mean ± SD age = 28.09 ± 6.55 years, height = 176.7 ± 2.97 cm, weight = 73.31 ± 8.44 kg, and VO2max = 60.93 ± 9.75 mL/kg/min) were recruited for the study to perform a VO2max test and an intense anaerobic test (the control), to compare the level of muscle fatigue at the end of the VO2max test. Following a load determining VO2max cycling trial, exercise trials were performed in a randomized order separated by at least seven days. For the VO2max tests, the participants performed a graded exercise protocol at 60 rpm on a mechanically braked cycle ergometer; the power output was set according to each subjects fitness level to complete the test in 8 to 10 minutes. The intense anaerobic test consisted of cycling on the same ergometer at 60 rpm and 100% of the initial Wattspeak. In both tests, the participants were encouraged to pedal constantly until reaching volitional exhaustion. The root mean square (RMS), mean power frequency (MPF), and median frequency (MF) were extracted and normalized using the maximal voluntary contraction (MVC) from the selected sEMG samples. MATLAB was used in order to observe the tendencies over time for the left and right rectus femoris, vastus medialis and vastus lateralis. Force production applied to the pedals was measured using four flexiforce load sensors (Teskan, Inc. Boston, MA. USA) installed within each pedal. Heart rate (HR) was monitored during the tests via a commercial clinical electrocardiogram (GE Medical Systems, Milwaukee, WI, USA). Bilateral MVCs were measured before and immediately after each test with the knee positioned at 60 degrees of flexion prior to the MVCs. A paired t-test was used to compare means from sEMG, heart rate and force production pre-test and post-test between both group trials with significance set at p\u3c0.05. Results. The percentage change in mean sEMG from baseline MVC values was significantly larger for the intense anaerobic tests at the end compared to the VO2max test for two of the six muscles monitored. For the left rectus femoris the remaining percentage of baseline MVC was 84.53 ± 15.01% and 89.9 ± 16.74, respectively, for the intense anaerobic and the VO2max trial; F(1,5)= 8.124, p = 0.036. Also, a significantly lower remaining percentage of baseline MVC was found for the anaerobic intense trial compared to the VO2max test for right vastus lateralis, 81.92 ± 8.0% and 93.12 ± 4.21% respectively; F(1,6)= 11.47, p = 0.015. There was a significant remaining difference in the median sEMG frequency for three of the six muscles monitored. A lower remaining percentage was found for the intense anaerobic test for the right vastus lateralis than for the VO2max test (80.54 ± 13.1% and 93.46 ± 8.78% respectively; F(1,6)= 7.58, p = 0.03. respectively). Similarly, the right rectus femoris showed a smaller remaining percentage for the anaerobic test than for the VO2max (82.5 ± 10.51% and 92.9 ± 8.85%; F(1,5)= 12.60, p = 0.016). The only muscle that showed a smaller remaining percentage for the VO2max compared to the intense anaerobic test was the left vastus medialis (79.39 ± 11.26% and 88.28 ± 9.6%, respectively; F(1,6)= 8.51, p = 0.027). No statistically significant differences were found for the post-test heart rate, force production and MVC. Conclusion. Mean and median frequency sEMG data provided the best way to analyze muscle fatigue at the end of a maximal test. From these signals muscle fatigue at the end of a VO2max test seems not to be maximal; there is a reserve of muscle fiber recruitment mainly from the slow-twitch fiber type.\u2

Muscle Fatigue in the Three Heads of the Triceps Brachii During a Controlled Forceful Hand Grip Task with Full Elbow Extension Using Surface Electromyography

The objective of the present study was to investigate the time to fatigue and compare the fatiguing condition among the three heads of the triceps brachii muscle using surface electromyography during an isometric contraction of a controlled forceful hand grip task with full elbow extension. Eighteen healthy subjects concurrently performed a single 90 s isometric contraction of a controlled forceful hand grip task and full elbow extension. Surface electromyographic signals from the lateral, long and medial heads of the triceps brachii muscle were recorded during the task for each subject. The changes in muscle activity among the three heads of triceps brachii were measured by the root mean square values for every 5 s period throughout the total contraction period. The root mean square values were then analysed to determine the fatiguing condition for the heads of triceps brachii muscle. Muscle fatigue in the long, lateral, and medial heads of the triceps brachii started at 40 s, 50 s, and 65 s during the prolonged contraction, respectively. The highest fatiguing rate was observed in the long head (slope = -2.863), followed by the medial head (slope = -2.412) and the lateral head (slope = -1.877) of the triceps brachii muscle. The results of the present study concurs with previous findings that the three heads of the triceps brachii muscle do not work as a single unit, and the fiber type/composition is different among the three heads

Coupling Robot-aided assessment and surface electromyography to evaluate wrist and forearm muscles activity, muscle fatigue and its effect on proprioception

Sensorimotor functions and an intact neural control of muscles are essential for the effective execution of movements during daily living tasks. However, despite the ability of human sensorimotor system to cope with a great diversity of internal and external demands and constraints, these mechanisms can be altered as a consequence of neurological disorders, injuries or just due to excessive effort leading to muscle fatigue. A precise assessment of both motor and sensory impairment is thus needed in order to provide useful cues to monitor the progression of the disease in pathological populations or to prevent injuries in case of workers. In particular, considering muscle fatigue, an objective assessment of its manifestation may be crucial when dealing with subjects with neuromuscular disorders for understanding how specific disease features evolve over time or for testing the efficacy of a potential therapeutic strategy. Indeed, muscle fatigue accounts for a significant portion of the disease burden in populations with neuromuscular diseases but, despite its importance, a standardized, reliable and objective method for fatigue measurement is lacking in clinical practice. The work presented in this thesis investigates a practical solution through the use of a robotic task and parameters extracted by surface electromyography signals. Moreover, a similar approach that combines robot-mediated proprioception test and muscle fatigue assessment has been developed and used in this thesis to objectively investigate the influence of muscle fatigue on position sense. Finally, the effect of posture on muscle activity, from a perspective of injuries prevention, has been examined. Data on adults and children have been collected and quantitative and objective information about muscle activity, muscle fatigue and joint sensitivity were obtained gaining useful insight both in the clinical context and in the prevention of workplace injuries. A novel method to assess muscle fatigue has been proposed together with the definition of an easy readable indicator that can help clinicians in the assessment of the patient. As for the impact of fatigue on the sensorimotor system, results obtained showed a decrease in wrist proprioceptive acuity which led also to a decline in the performance of a simple tracing task. Regarding the adoption of different muscle strategies depending on postures, results showed that muscle activity of forearm muscles was overall similar regardless from the postures