The goal of this paper is to examine the trapezius muscle tone by measuring simultaneously using Myoton-2 myometer i.e., the natural oscillation frequency, stiffness and the elasticity of the trapezius muscle. With this method, the mechanical response of the muscle, to a short applied mechanical impulse, is registered by an acceleration probe. From the acquired damped natural oscillation waveform, the frequency (Hz), the stiffness (N/m) and the logarithmic decrement of damping (characterizing tissue's elasticity) are calculated, quantifying the functional state of the muscle. The trapezius muscle on both sides of the body was tested in twenty adult women by two investigators using the Myoton-2 myometer. During the measurements, the subjects were in a relaxed sitting position. The Bland and Altman graphical test, comparing the differences of the measurements of two investigators, was used for assessing the inter-observer repeatability. The registered values for the trapezius muscle tension, stiffness and elasticity are varying between the tested subjects, but the intra-class correlation coefficient (ICC) was near 1 for three muscular properties, showing that the variation within the subject (due to the investigator) is negligible, compared with the variation between the subjects.
The aim of the study was to characterize the electromechanical properties of skeletal muscle during isometric loading as well as to assess the potential of estimating intramuscular pressure by electrical and mechanical methods. Simultaneous electromyography (EMG), mechanical myotonometry (MYO, frequency and decrement of decay) and intramuscular pressure (IMP) measurements were conducted at rest and during short-term and long-term isometric contractions in patients with chronic pain in the anterior leg or dorsal forearm. The EMG amplitude and MYO(freq) accounted significantly (24-73%, p < 0.0001) for the variations in the IMP under short-term isometric loading. The IMP, EMG and MYO(freq) increased linearly with the relative muscle load (r = 0.868-0.993, p < 0.05). Mean values of EMG amplitudes at the contraction levels of 75% and 100% maximum voluntary contraction (MVC) and MYO(freq) values at all contraction levels (0-100% MVC) were higher for subjects with pathological values of IMP than for those with IMP values in the normal range. Total changes in IMP and EMG amplitude during 1 min isometric contraction were linearly interrelated (r = 0.747, p < 0.0001). We conclude that both surface electromyography and myotonometry parameters are indicative of intramuscular pressure, but neither of these methods can be used alone to diagnose non-invasively chronic compartment syndrome with acceptable accuracy.
The human resting muscle tone (HRMT) system provides structural and functional support to skeletal muscle and associated myofascial structures (tendons, fascia) in normal life. Little information is available on changes to the HRMT in bed rest. A set of dynamic oscillation mechanosignals ([Hz], [N/m], log decrement, [ms]) collected and computed by a hand-held digital palpation device (MyotonPRO) were used to study changes in tone and in key biomechanical and viscoelastic properties in global and postural skeletal muscle tendons and fascia from a non-exercise control (CTR) and an exercise (JUMP) group performing reactive jumps on a customized sledge system during a 60 days head-down tilt bed rest (RSL Study 2015–2016). A set of baseline and differential natural oscillation signal patterns were identified as key determinants in resting muscle and myofascial structures from back, thigh, calf, patellar and Achilles tendon, and plantar fascia. The greatest changes were found in thigh and calf muscle and tendon, with little change in the shoulder muscles. Functional tests (one leg jumps, electromyography) showed only trends in relevant leg muscle groups. Increased anti-Collagen-I immunoreactivity found in CTR soleus biopsy cryosections was absent from JUMP. Results allow for a muscle health status definition after chronic disuse in bed rest without and with countermeasure, and following reconditioning. Findings improve our understanding of structural and functional responses of the HRMT to disuse and exercise, may help to guide treatment in various clinical settings (e.g., muscle tone disorders, neuro-rehabilitation), and promote monitoring of muscle health and training status in personalized sport and space medicine.
We welcome the proposal by Sedentary Behaviour Research Network (2012) to define standard terms whereby to describe our researches into the modern problem of excessive sitting. However, we have some concerns.Neither standing nor sitting can adequately be described just in terms of energy expenditure or neuromuscular activity. We must also include the seemingly subtle but measurable and significant effect of gravity on those muscles holding the body upright (Viir et al. 2007;Veraksitš et al. 2012).Furthermore, if one defines "reclining" as lying down, then that is not "sedentary behaviour" at all; on the contrary, it has the crucial function of obtaining relief from the above effort, as we have shown (Viir et al. 2007;Veraksitš et al. 2012), and this has important application in rehabilitation (Viir et al. 2008).For our research to be thorough it is important to be alert to the significant effect of gravity, subtle though it may be.
VO2max is considered single best indicator of cardiovascular fitness and aerobic endurance. We analyzed retrospectively, are there any relationships between muscle parameters and oxygen consumption in a study where the myoton equipment was used to establish muscle biomechanical properties, such as elasticity, stiffness, and tension (measured as oscillation frequency) in triathletes. Eight muscles were studied in 14 male triathletes over three years. Relaxed and contracted states of muscles were measured. VO2max was recorded in these athletes up to four times during this period. Average values were calculated for each athlete and High (max 71.8 to min 62.3 ml/kg/min) and Low (59.1 to 51.3) oxygen consumption groups were formed. Higher oxygen consumption correlated significantly (r=-0.58; p=0.029) with improved elasticity (represented by smaller decrement values) of the rectus femoris muscle in a contracted state. Also, in the High VO2max group, this muscle (in a relaxed state) was significantly more elastic and stiffer at the same time compared to the Low group. An ultrasound registration was also conducted to observe the depth of the device's impact in the posterior crural muscles. It was confirmed that deep and substantial tissue disturbances were caused by this impact. According to our findings, myotonometry is an adequate method to establish muscle parameters. Elasticity and stiffness of the rectus femoris muscle may determine success in triathlon.
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