Evaluation of limbs muscle function is one of the difficult tasks in forensic clinical medicine. Recently, there are more and more cases needed to be evaluated on the limbs muscle function in forensic clinical appraisal. Thus the assessment methods for muscle function have been concerned increasingly. This paper introduces the classification of muscle function and the type of muscle contraction, reviews the assessment methods for muscle function and their application value, such as manual muscle test, simple instrumental muscle test, isokinetic muscle test and electrophysiological test. It has also proposed to evaluate the muscle function with multiple methods comprehensively.
Biomechanical Phenomena ; Electromyography/methods* ; Exercise Test/methods* ; Extremities/physiology* ; Forensic Medicine ; Humans ; Isometric Contraction/physiology* ; Muscle Contraction/physiology* ; Muscle Strength/physiology* ; Muscle Tonus ; Muscle, Skeletal/physiology* ; Muscles/physiology*

OBJECTIVETo characterize the isometric contractility of Bufo gastrocnemius ex vivo in light of the rest tension.

METHODSBufo gastrocnemius treated with SOD inhibitor and ascorbate was stimulated electrically (12 V DC, 2 ms duration with a 2 s interval) to record the tension within 10 min. Weighted fitting to the relaxation curve of the tension below 90% of the peak tension with a mono-exponential model yielded the rest tension and relaxation rate.

RESULTSThe control gastrocnemius showed monotonic decrease of the rest tension, but treatment with SOD inhibitor and ascorbate resulted in a decrease of the rest tension followed by a fast increase within a 1.0 min contraction. The increase of the rest tension at 7.0 min of contraction of the treated muscle was significantly greater than that of the control muscle. The control muscle showed a monotonic decrease of the relaxation rate in 10 min, whereas treatment with SOD inhibitor and ascorbate produced increased relaxation rate followed by monotonic decrease till a plateau was reached. In the course of the 10 min recording, the relaxation rate of the treated muscle was lower than that of the control after the same duration of contraction.

CONCLUSIONRest tension is a characteristic index to represent the skeletal muscle contractility.

Animals ; Bufonidae ; Electric Stimulation ; In Vitro Techniques ; Isometric Contraction ; physiology ; Muscle Tonus ; physiology ; Muscle, Skeletal ; physiology

AIMTo analyze the most force rising ratio (+ dF/dt(max)) and the most force descending ratio (- dF/dt(max)) for more sensitive index of skeletal contractility.

METHODSMouse model of swimming training was used, most force (f(max)), + dF/dt(max) and - dF/ dt(max) of gastrocnemius contracting were measured and changes of gastrocnemius supermicro-structure was observed.

RESULTSMitochondria increased and myoneme was regular in general training load, gastrocnemius F(max) - dF/dt(max) significantly increased than in control (P < 0.05), + dF/dt(max) increased more significantly (P < 0.01). Mitochondria was rare and myoneme was unusual in overtraining load, gastrocnemius F(max), - dF/dt(max) reduced significantly than in control (P < 0.05), + dF/dt(max) reduced more significantly (P < 0.01).

CONCLUSION+ dF/dt(max) is better index than F(max) in judging skeletal contractility.

Animals ; Female ; Mice ; Mice, Inbred BALB C ; Muscle Contraction ; physiology ; Muscle, Skeletal ; physiology ; ultrastructure ; Swimming ; physiology

There are many factors affecting the outflow facility. Structural changes of aqueous outflow channel by ciliary muscle contraction play major role in the control of outflow facility. Although many studies on the physiology of outflow facility have been done by many authors, the lens effect on the ciliary muscle contractability has not been reported. We performed clear corneal phacoemulsification and foldable intraocular lens implantation in 42 cataract patients and measured intraocular pressure(IOP) pre and postoperatively by Goldmann applanation tonometer and determined outflow facility with and without 2% pilocarpine before and after cataract surgery, respectively. We analysed IOP changes after surgery, and assessed ciliary muscle contractability by analysing outflow facility changes. Statistical analysis was done by Wilcoxon`s signed rank test. IOP decreased by 2.4+/-0.4mmHg(mean+/-SEM)(P<0.001): outflow facility with and without pilocarpine increased by 0.080+/-0.012microliter/min/mmHg(P<0.001) and 0.045+/-0.006microliter/min/mmHg(P<0.01), respectively after lens extraction: outflow facility increased 2.8+/-0.4 times by pilocarpine itself after lens extraction(P<0.001). The lens connected to the ciliary muscle muscle by zonnule may have an influence on ciliary muscle contractability.
Cataract ; Humans ; Lens Implantation, Intraocular ; Muscle Contraction ; Phacoemulsification ; Physiology ; Pilocarpine

The architecture and dynamic properties of human muscles are very complex. So, most of the muscles are represented simply by straight-line or curve in musculoskeletal model. The straight-line and curve are called muscle paths. The representation of the muscle path plays a vital role in musculoskeletal model simulation such as the estimation of muscle force. Firstly, we create a black box with the muscle force on the bones as the output signal. Then based on the assumption that there is a muscle path plane (MPP) at any time during joint movement, we construct the space curve function of the muscle path during joint instantaneous movement by mathematical approaches. Finally, we calculate the lengths of the muscle paths and analyze the changes of them during elbow flexion.
Algorithms ; Computer Simulation ; Elbow Joint ; physiology ; Humans ; Models, Anatomic ; Movement ; Muscle Contraction ; Muscle, Skeletal ; physiology

Long-term endurance training or physical activity has been confirmed not only to improve physical performance, but to bring about an obvious beneficial effect on human health; however, the mechanism of this effect is not clear. The most studied health adaptations in skeletal muscle response to endurance exercise are increased muscle glycogen level and insulin sensitivity, fiber type transformation toward oxidative myofibers, and increased mitochondrial content/function. Mitochondria are dynamic organelles in eukaryotic cells critical in physical performance and disease occurrence. The mitochondrial life cycle spans biogenesis, maintenance, and clearance. Exercise training may promote each of these processes and confer positive impacts on skeletal muscle contractile and metabolic functions. This review focused on the regulation of these processes by endurance exercise and discussed its potential benefits in health and disease. We presented evidence suggesting that exercise training potentiates not only the biogenesis of mitochondria but also the removal of old and unhealthy mitochondria through mitochondrial quality control.
Adaptation, Physiological ; Exercise ; Humans ; Mitochondria ; physiology ; Muscle Contraction ; Muscle, Skeletal ; physiology

Aiming at the difficulty of surface electromyography (SEMG) signal decomposition, we in this paper proposed a method of gradual processing based on contraction force level of muscle. At first, SEMG signals were recorded at different levels of muscle contraction force. Then, the SEMG data recorded at minimum level of contraction force were decomposed adopting the conventional methods. Further, the data at higher level of contraction force was decomposed using the templates and inter-pulse interval (IPI) information resulted from the previous composition performed at lower level of contraction force. Such procedure was iteratively performed level by level until the SEMG data at the maximal level of contraction force were successfully decomposed. The experimental results showed that the proposed method was effective in decomposing SEMG data, offering a valuable solution to the difficulty in obtaining templates at relatively high level of muscle contraction force. The complexity of SEMG decomposition in the case of high level of contraction force could also be reduced to a certain extent by using the proposed method.
Action Potentials ; Algorithms ; Electromyography ; methods ; Humans ; Muscle Contraction ; physiology ; Muscle, Skeletal ; physiology ; Signal Processing, Computer-Assisted

The decomposition method of surface electromyography (sEMG) signals was explored by using the multi-channel information extraction and fusion analysis to acquire the motor unit action potential (MUAP) patterns. The action potential waveforms were detected with the combined method of continuous wavelet transform and hypothesis testing, and the effective detection analysis was judged with the multi-channel firing processes of motor units. The cluster number of MUAPs was confirmed by the hierarchical clustering technique, and then the decomposition was implemented by the fuzzy k-means clustering algorithms. The unclassified waveforms were processed by the template matching and peel-off methods. The experimental results showed that several kinds of MUAPs were precisely extracted from the multi-channel sEMG signals. The space potential distribution information of motor units could be satisfyingly represented by the proposed decomposition method.
Action Potentials ; physiology ; Algorithms ; Electromyography ; methods ; Humans ; Muscle Contraction ; Muscle, Skeletal ; physiology ; Signal Processing, Computer-Assisted

In order to provide data for clinical approach to Hand-functional rehabilitation, we conducted this study on the relationships among flexor tendon load, tendon excursion and finger joint angle. Using the dynamic biomechanical test, three-dimension motion image analysis and computer analysis, we investigated eight intact normal male cadavers, hand mechanics of flexor tendon load, tendon excursion and joint angle. The results showed that, at the time when the top of finger touched the palm, the mean tendon load of flexor digitorum profundus(FDP) tendon was 7.9 N, the mean tendon excursion 43.4 mm, the mean total range of motion 237.0 degree. When the top of finger touched the palm, the mean tendon load of flexor digitorum superficial(FDS) tendon was 8.9 N, the mean tendon excursion 38.5 mm, and the mean total range of motion 206.3 degree. These findings demonstrated that there are some curvilinear relationships between flexor tendon load, tendon excursion and finger joint motion. When we flex our fists, the proximal interphalangeal(PIP) joint plays an important role in both FDP and FDS tendon.
Biomechanical Phenomena ; Cadaver ; Finger Joint ; physiology ; Fingers ; physiology ; Humans ; Male ; Muscle Contraction ; Muscle, Skeletal ; physiology ; Range of Motion, Articular ; Tendons ; physiology

AIMTo explore the factors affect the change of sEMG signal by investigating the relationship between power spectral changes of sEMG signal and H+ in muscle during the short period of recovery after muscular fatigue.

METHODSAfter a fatiguing constriction of the muscle, its pH value would not be featured any apparent changes in a short period of time. However, we were able to observe the movement rule of the sEMG power spectrum within 30 s of its reversion duration. Surface EMGs of biceps brachii muscle were recorded from 8 healthy human volunteers during tasks. Muscle fatigue induced by isometric loading that included 60% of maximal voluntary contraction. Restitution of sEMG by recording 2 s, 4 s, 6 s, 8 s, 10 s, 20 s and 30 s by the same load after the end of the fatigue experiments of 60% MVC.

RESULTSThere was a significant monotonous decline in MPF during isometric fatigue contraction of 60% MVC. MPF was restituted rapidly in the short recovery period after muscular fatigue. It was recovered 26.5% of its whole declining scope only 2 s by the end of muscle movement, and has been reached 87.7% of its total decreasing value till 30 s after the exercise.

CONCLUSIONOur results suggested that the accumulation of H+ in muscle was not the only factor that affected "spectrum shift" during muscle fatigue. The change of CNS drive strategy might be the important mechanisms that attributed to the change of SEMG signal during isometric contractions.

Adult ; Electromyography ; Exercise ; Humans ; Isometric Contraction ; physiology ; Male ; Muscle Fatigue ; physiology ; Muscle, Skeletal ; physiology ; Physical Endurance ; physiology ; Young Adult