Based on the joint analysis of EMG spectrum and amplitude method (JASA), a study on muscle fatigue assessment of spinal surgical instruments based on surface EMG signals was carried out, and a comparative evaluation of the operating comfort before and after the optimization of spinal surgical instruments was completed. A total of 17 subjects were recruited to collect the surface EMG signals of their brachioradialis and biceps. Five surgical instruments before and after optimization were selected for data comparison, and the operating fatigue time proportion of each group of instruments under the same task was calculated based on the RMS and MF eigenvalues. The results showed that when completing the same operation task, the operation fatigue time of the surgical instruments before optimization was significantly higher than that after optimization (P<0.05); there was no significant difference in the fatigue status of brachioradialis and biceps when operating the same instrument (P>0.05). These results provide objective data and reference for the ergonomic design of surgical instruments and fatigue damage protection.
Humans ; Muscle Fatigue/physiology* ; Muscle, Skeletal ; Electromyography ; Ergonomics

In this study, a surface electromyography (sEMG) and blood oxygen signal real-time monitoring system is designed to explore the changes of physiological signals during muscle fatigue, so as to detect muscle fatigue. The analysis method of sEMG and the principle of blood oxygen detection are respectively introduced, and the system scheme is expounded. The hardware part of the system takes STM32 as the core. Conditioning module composition; blood oxygen signal acquisition is based on near infrared spectroscopy (NIRS), specifically including light source, light source driving, photoelectric conversion, signal conditioning and other modules. The system software part is based on the real-time uC/OS-III software system. The characteristic parameters of sEMG were extracted by isometric contraction local muscle fatigue experiment; the relative changes of oxyhemoglobin (HbO₂) and deoxyhemoglobin (Hb) were calculated in the forearm blocking experiment, thereby verifying that the system collects two signals effectiveness.
Muscle, Skeletal ; Oxygen ; Electromyography ; Muscle Fatigue/physiology* ; Computers

OBJECTIVE: To investigate the effect of M3P (containing Deer antler, Cordyceps sinensis, Rhodiola rosea, and Panax ginseng); an herbal remedy with the function of tonifying Kidney (Shen) and invigorating Spleen (Pi), replenishing qi and nourishing blood; on fatigue alleviation, endurance capacity and toxicity. METHODS: Swimming with weight-loading of 24 male ICR mice was used to evaluate the endurance capacity, and fatigue-related plasma biomarkers were determined. Mice were randomly assigned to control or M3P treatment groups with 6 mice for each group and were orally administered with M3P everyday for 8 weeks at doses 0, 10, 33 or 100 mg/kg. Swimming time to exhaustion was measured in a specialized water tank. Lliver and kidney functions, body weight, and hematological profile were determined to evaluate the safety and toxicity after long-term M3P administration. RESULTS: M3P supplementation 100 mg/kg significantly increased swimming endurance time up to approximate 2.4 folds of controls (P<0.05). The plasma concentrations of cortisol and hepatic glycogen content were significantly increased in mice received M3P (P<0.05, P<0.01 respectively). The lactic acid level and blood glucose were not changed after M3P treatment (P>0.05). The liver and kidney functions muscle damage biomarker creatine, body weight, and hemograms were not altered in M3P supplementation (P>0.05). CONCLUSION M3P supplementation may improve swimming endurance accompanied by increasing hepatic glycogen content and serum cortisol level without major toxicity.
Animals ; Body Weight ; Deer ; Dietary Supplements ; Fatigue/drug therapy* ; Hydrocortisone ; Liver Glycogen ; Male ; Mice ; Mice, Inbred ICR ; Muscle, Skeletal ; Swimming/physiology*

OBJECTIVETo evaluate the exercise-induced fatigue in operators during pesticide spraying based on surface electromyography (sEMC) signals and heart rate.

METHODSThe sEMG signals were recorded from the right trapezius, biceps brachii, extensor digitorum, and flexor digitorum of 19 operators by portable electromyography units during pesticide spraying using 3WS-16 manual sprayers. Meanwhile, the heart rate of operators was measured by the ambulatory blood pressure monitoring system. The changes in median frequency and heart rate were analyzed.

RESULTSPesticide spraying was defined as low-intensity labor. The median frequency of the right trapezius, biceps brachii, extensor digitorum, and flexor digitorum decreased significantly as pesticide spraying went on (P < 0.05). The body remained in a state of slight fatigue from 8 min after pesticide spraying began to the end of the operation.

CONCLUSIONThe degree of exercise-induced fatigue of operators can be evaluated based on sEMG signals and heart rate during pesticide spraying.

Arm ; Blood Pressure Monitoring, Ambulatory ; Electromyography ; Hand ; Heart Rate ; Humans ; Muscle Fatigue ; Muscle, Skeletal ; physiology ; Occupational Exposure ; adverse effects ; Pesticides ; Physical Exertion

This study investigated the effect of prolonged walking with load carriage on body posture, muscle fatigue, heart rate and blood pressure of the tested subjects. Ten healthy volunteers performed 30 min walking trials on treadmill (speed = 1.1 m/s) with different backpack loads [0% body weight (BW), 10% BW, 15% BW and 20% BW]. The change of body posture, muscle fatigue, heart rate and blood pressure before and after walking and the recovery of muscle fatigue during the rest time (0, 5, 10 and 15 min) were collected using the Bortec AMT-8 and the NDI Optotrak Certus. Results showed that the forward trunk and head angle, muscle fatigue, heart rate and blood pressure increased with the increasing backpack loads and bearing time. With the 20% BW load, the forward angle, muscle fatigue and systolic pressure were significantly higher than with lighter weights. No significantly increased heart rate and diastolic pressure were found. Decreased muscle fatigue was found after removing the backpack in each load trial. But the recovery of the person with 20% BW load was slower than that of 0% BW, 10% BW and 15% BW. These findings indicated that the upper limit of backpack loads for college-aged students should be between 15% BW and 20% BW according to muscle fatigue and forward angle. It is suggested that backpack loads should be restricted to no more than 15% BW for walks of up to 30 min duration to avoid irreversible muscle fatigue.
Blood Pressure ; Body Weight ; Exercise Test ; Healthy Volunteers ; Heart Rate ; Humans ; Muscle Fatigue ; Posture ; Walking ; physiology ; Weight-Bearing

This paper presents a preliminary study of rabbit experiment modality incorporating a new indicator for evaluating cardiac function changes, providing a basis for subsequent study of cardiac fatigue. Using only biochemical indicators, such as troponins, is difficult to make a distinction between exercise-induced cardiac fatigue (EICF) and exercise-induced cardiac damage (EICD). Therefore, some new indicators are needed to evaluate cardiac fatigue synthetically. In our study, we used New Zealand white rabbits to conduct a multi-step swimming experiments with load. We made the rabbits reach an exhaustive state to evaluate whether the amplitude ratio of the first to second heart sound (S1/S2) and heart rate (HR) during the exhaustive exercise would be decreased and whether they would be able to recover after the exhaustive exercise for 24 hours. During the first phase of swimming, S1/S2 and HR were increased, and then decreased at exhaustive state. They were recovered after the exhaustive exercise for 24 hours. Overloading led to deaths of three rabbis, and new phenomena from overloading and related to this kind of death were observed. The experiments proved that Multi-steps swimming experiments with loads by using New Zealand white rabbit is useful for studying cardiac fatigue and premonition of sudden cardiac death.
Animals ; Cardiovascular Physiological Phenomena ; Death, Sudden, Cardiac ; Female ; Heart ; physiology ; Heart Rate ; physiology ; Male ; Muscle Fatigue ; physiology ; Myocardial Contraction ; physiology ; Myocardium ; chemistry ; Physical Endurance ; physiology ; Rabbits ; Stress, Physiological ; physiology ; Swimming

OBJECTIVETo explore the mechanism of manipulation in treating cervical spondylosis.

METHODSFrom August 2008 to December 2009, 65 patients with cervical spondylosis were randomly divided into manipulation group and traction group. There were 32 patients in manipulation group, of which 30 cases obtained followed-up, including 10 males and 20 females, ranging in age from 30 to 65 years,with an average of (42.31 +/- 13.23) years; the mean course of diseases was (12.40 +/- 6.23) months, and the average weight was (61.21 +/- 10.23) kg. In traction group, there were 33 patients, 30 cases obtained follow-up, including 11 males and 19 males, ranging in age from 30 to 65 years, with an average of (45.54 +/- 14.35) years; the mean course of diseases was (13.25 +/- 6.06) months and average weight was (62.31 +/- 10.45) kg. Biodex III Isokinetic Testing System and TeleMyo 2400 T Surface EMG was applied to test the mechanical properties and fatigue of neck muscles before and after treatment.

RESULTSThe mechanical properties of neck muscles: measuring in the 60 degrees/s and 120 degrees/s angular velocity, there were no significant difference (P > 0.05) in peak torque (PT), average power (AP), peak torque of flexor/extensor peak torque ratio (F/E) before treatment, while manipulation group was improved more than traction group in PT, AP, F/E after treatment (P < 0.05), and there was significant difference (P < 0.05). For the degree of fatigue: there was no significant difference (P > 0.05) in IEMG, MPF compared by two groups before treatment, but the manipulation group was improved more than the traction group in IEMG, MPF after treatment (P < 0.05), and there was significant difference (P < 0.05) on the right side.

CONCLUSIONManipulation can improve contraction forces and work efficiency of neck muscle, coordination ability of flexors and extensors muscles, efficiency of neck muscle, and recover mechanical properties and can alleviate fatigue of neck muscles in patients with cervical spondylosis.

Adult ; Biomechanical Phenomena ; Cervical Vertebrae ; physiopathology ; Female ; Humans ; Male ; Manipulation, Spinal ; Medicine, Chinese Traditional ; Middle Aged ; Muscle Contraction ; Muscle Fatigue ; physiology ; Spondylosis ; physiopathology ; therapy

OBJECTIVETo explore the relationship between contractile characteristics and fiber type conversion in hind-limb unloading mice soleus.

METHODSAfter 28-day hind-limb unloading and muscle atrophy, we used the method of isolated muscle perfusion with different stimulated protocols to determine the changes in contractile characteristics including the isometric twitch force and tetanus force and fatigue index of slow twitch muscle in mice. The muscle myofibrillar composition and fiber type conversion were detected by immunofluorescence staining and real-time PCR.

RESULTSThe isometric twitch force and the tetanus force and fatigue index were decreased progressively in 28-day unloaded mice soleus, with the increase in fast twitch fiber subtype and the decrease in slow twitch fiber subtype.

CONCLUSIONThe alteration of contractile characteristics is relevant to the slow-to-fast fiber conversion in mice soleus after 28-day hind-limb unloading.

Animals ; Hindlimb Suspension ; physiology ; Mice ; Mice, Inbred C57BL ; Muscle Contraction ; physiology ; Muscle Fatigue ; physiology ; Muscle Fibers, Fast-Twitch ; physiology ; Muscle Fibers, Slow-Twitch ; physiology ; Muscle, Skeletal ; pathology ; physiology ; Muscular Atrophy

There are actually no sufficient data for lifting technique assessment. A laboratory study was undertaken to determine the effect of 3 regular lifting techniques on erector muscle activation, cardiovascular strain and subjective response. Thirty student volunteers participated in the study, and were required to lift a weight with different techniques. Stoop-, squat-, semi-squat-lifting resulted in 3, 2 and 1 time of the highest percentage of the maximum voluntary electrical activation (MVE%) respectively. In the same order, the lowest median frequency (MF) existed 1, 1 and 2 times. Muscle fatigue was 4 times in squat, 36 in semi-squat and 43 in stoop lifting. Heart rate was the highest in squat and lowest in stoop respectively, with a middle level in semi-squat lifting. It may be recommended to adopt mainly the semi-squat technique for daily lifting works. For heavy lifting, it should use the squat technique. Stoop lifting may also be used alternatively but for light things.
Adult ; Biomechanical Phenomena ; physiology ; Female ; Humans ; Lifting ; Male ; Muscle Fatigue ; physiology ; Muscle, Skeletal ; physiology ; Young Adult

OBJECTIVETo analyze and evaluate the fatigue of shoulder skeletal muscle caused by different lifting loads with surface electromyography (sEMG).

METHODSAccording to the loading standard of1 Repetition Maximum (1RM), ten male volunteers performed 3 tasks of upper limb flexion, i.e. 10%, 50% and 90%-1RM. During action process, the signals of Upper Trapezius (UT), Lower Trapezius (LT), Serratus Anterior (SA) and Anterior Deltoid (AD) were recorded by sEMG. The Mean Amplitude (MA) served as an index to evaluate the changes in skeletal muscle fatigue.

RESULTSThe scores of Borg were 15.6, 15.9 and 15.2 for 3 loads of 10%-1RM, 50%-1RM and 90%-1RM, respectively (P > 0.05). The mean amplitudes (MAs) of Upper Trapezius, Lower Trapezius, Anterior Deltoid and Serratus Anterior in shoulders increased obviously. Under the load intensity of 10%-1RM, the MAs of Upper Trapezius and Anterior Deltoid increased significantly (P < 0.05), which were 0.898 and 0.736, respectively. After the exhaustion, the contribution of mean amplitude in shoulder muscle did not change significantly (P > 0.05).

CONCLUSIONThe low-load action for long time can induce easily the fatigue of upper trapezius and anterior deltoid.

Adult ; Electromyography ; Humans ; Lifting ; Male ; Muscle Fatigue ; physiology ; Muscle, Skeletal ; physiology ; Shoulder ; physiology ; Workload