Quadriceps muscle tone, elasticity and stiffness in older males: reliability and symmetry using the MyotonPRO.

Portable tensiomyography (TMG) and myotonometry (MMT) devices have been developed to measure mechanical and contractile properties of skeletal muscle. The aim of this study was to explore the sensitivity of the aforementioned techniques in detecting a change in passive mechanical properties of the biceps femoris (BF) muscle as a result of change in knee joint angle (i.e. muscle length). BF responses were assessed in 16 young participants (23.4 ± 4.9 years), at three knee joint angles (0°, 45° and 90°), for maximal isometric torque (MIT) along with myo-electrical activity. Contractile and mechanical properties were measured in a relaxed state. Inter-day reliability of the TMG and MMT was also assessed. MIT changed significantly (p < 0.01) across the three angles, so did stiffness and other parameters measured with MMT (p < 0.01). Conversely, TMG could detect changes only at two knee angles (0° and 45°, p < 0.01), when there is enough tension in the muscle. Reliability was overall insufficient for TMG whilst absolute reliability was excellent (coefficient of variation < 5%) for MMT. The ability of MMT more than TMG to detect an inherent change in stiffness can be conceivably exploited in a number of clinical/therapeutic applications that have to do with unnatural changes in passive muscle stiffness.

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The effectiveness of two novel techniques in establishing the mechanical and contractile responses of biceps femoris.

Five male triathletes of the Estonian national junior team were observed during a seven-week competition period. The Myoton-2 equipment was used to describe the viscoelastic parameters of the skeletal muscles. The frequency of damped mechanical oscillation of the muscle tissue (Hz - indicating the tension in the muscle), logarithmic decrement of the oscillations (Theta - indicating the elasticity of the muscle) and stiffness (N m(-1)) of the muscle tissue were registered bilaterally in eight muscles in both the relaxed and the contracted states: BB - biceps brachii (caput longum); TB - triceps brachii (caput longum); BF - biceps femoris (caput longum); RF - rectus femoris; TA - tibialis anterior; GC - gastrocnemius (caput mediale); LD - latissimus dorsi; PM - pectoralis major (pars sternocostalis). A portable massage table was used for the subject to rest on during the measuring. For the measurement of the anterior muscles, the subject lay supine; for the posterior muscles the prone position was used. The (isometric) contraction was standardized simply by the same measuring position of the limb-the subject raised his arm or leg to an angle of 45 degrees from the horizontal level, using a 2.3 kg dumb-bell as an additional weight for the upper limb. The tarsal dorsiflexion and plantarflexion was performed against a fixed table to contract the crural muscles. The elasticity of the skeletal muscle is higher for the contracted state with respect to the relaxed one (p < 0.0001) and is described by decline of the value of logarithmic decrement, the stiffness and the tension in the muscle increases (p < 0.0001 for both parameters). The measured skeletal muscles differ significantly (p < 0.0018) by the viscoelastic properties in the relaxed state. In the relaxed state, TA was the most elastic (mean +/- SD; Theta-0.74 +/- 0.13), stiff (mean +/- SD; 346.68 +/- 60.34 N m(-1)) and tense muscle (mean +/- SD; 18.72 +/- 1.55 Hz). In the contracted state, the elasticity of TA did not change (0.76 +/- 0.14) while the stiffness and the tension in this muscle rose significantly (93% and 38%, accordingly). Personal differences (p < 0.005) exist if pooled data from the muscles are compared between the subjects.

https://iopscience.iop.org/article/10.1088/0967-3334/28/6/002/pdf

Evaluation of viscoelastic parameters of the skeletal muscles in junior triathletes.

Evaluation of viscoelastic parameters of the skeletal muscles in junior triathletes. Physiol Meas

Physical exercise is important for people living under extreme environmental conditions to stay healthy Particularly in space, exercise can partially counteract the loss of muscle mass and muscle strength caused by microgravity Monitoring the adaptation of the musculoskeletal system to assess muscle quality and devise individual training programmes is highly desirable but is restricted by practical, technical and time constraints on board the International Space Station This study aimed to test the feasibility of using myometric measurements to monitor the mechanical properties of skeletal muscles and tendons in weightlessness during parabolic flights The mechanical properties (frequency, decrement, stiffness relaxation time and creep) of the m gastrocnemius, m erector spinae and Achilles tendon were assessed using the hand-held MyotonPRO device in 11 healthy participants (aged 47 ± 9 years) in normal gravity as well as in microgravity during two parabolic flight campaigns Results showed significant (p < 05-001) changes in all mechanical properties of both muscles and the Achilles tendon, indicating a more relaxed tissue state in microgravity Recordings from a phantom rubber material with the device in a test rig confirmed that the device itself was not affected by gravity, as changes between gravity conditions that were too small (<1 %) to explain the changes observed in the tissues It is concluded that myometric measurements are a feasible, easy-to-use and non-invasive approach to monitor muscle health in extreme conditions that prohibit many other methods Real-time assessment of the quality of a muscle being exposed to the negative effect of microgravity and also the positive effects of muscular training could be achieved using Myoton technology

/pdf/feasibility-of-monitoring-muscle-health-in-microgravity-4faboi5nf1.pdf

Feasibility of monitoring muscle health in microgravity environments using Myoton technology

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 MYOfreq accounted significantly (24–73%, p < 0.0001) for the variations in the IMP under short-term isometric loading. The IMP, EMG and MYOfreq 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 MYOfreq 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.

http://iopscience.iop.org/article/10.1088/0967-3334/26/6/006/pdf

R Viir

Papers

Can mechanical myotonometry or electromyography be used for the prediction of intramuscular pressure