BACKGROUNDOur previous study has confirmed that one bout of exhaustion (Ex) can cause hippocampus neurocyte damage, excessive apoptosis, and dysfunction. Its initial reason is intracellular calcium overload in hippocampus triggered by N-methyl-D-aspartic acid receptor (NMDAR) over-activation. NMDAR activation can be suppressed by γ-aminobutyric acid (A) receptor (GABAAR). Whether GABAAR can prevent intense exercise-induced hippocampus apoptosis, damage, or dysfunction will be studied in this study.

METHODSAccording to dose test, rats were randomly divided into control (Con), Ex, muscimol (MUS, 0.1 mg/kg) and bicuculline (BIC, 0.5 mg/kg) groups, then all rats underwent once swimming Ex except ones in Con group only underwent training. Intracellular free calcium concentration ([Ca2+]i) was measured by Fura-2-acetoxymethyl ester; glial librillary acidic protein (GFAP) and synaptophysin (SYP) immunofluorescence were also performed; apoptosis were displayed by dUTP nick end labeling (TUNEL) stain; endoplasmic reticulum stress-induced apoptosis pathway was detected by Western blotting analysis; Morris water maze was used to detect learning ability and spatial memory.

RESULTSThe appropriate dose was 0.1 mg/kg for MUS and 0.5 mg/kg for BIC. Ex group showed significantly increased [Ca2+]i and astrogliosis; TUNEL positive cells and levels of GFAP, B cell lymphoma-2 (Bcl-2) associated X protein (Bax), caspase-3, caspase-12 cleavage, CCAAT/enhancer binding protein homologous protein (CHOP), and p-Jun amino-terminal kinase (p-JNK) in Ex group also raised significantly compared to Con group, while SYP, synapse plasticity, and Bcl-2 levels in Ex group were significantly lower than those in Con group. These indexes were back to normal in MUS group. BIC group had the highest levels of [Ca2+]i, astrogliosis, TUNEL positive cell, GFAP, Bax, caspase-3, caspase-12 cleavage, CHOP, and p-JNK, it also gained the lowest SYP, synapse plasticity, and Bcl-2 levels among all groups. Water maze test showed that Ex group had longer escape latency (EL) and less quadrant dwell time than Con group; all indexes between MUS and Con groups had no significant differences; BIC had the longest EL and least quadrant dwell time among all groups.

CONCLUSIONSActivation of GABAA R could prevent intense exercise-induced synapses damage, excessive apoptosis, and dysfunction of hippocampus.

Animals ; Apoptosis ; physiology ; Body Weight ; physiology ; Endoplasmic Reticulum Stress ; physiology ; Hippocampus ; metabolism ; Male ; Physical Exertion ; physiology ; Rats ; Rats, Sprague-Dawley ; Receptors, GABA ; genetics ; metabolism ; Synapses ; pathology

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

INTRODUCTIONAccording to the findings of some studies, instability due to inertia during changes in speed may negatively impact the quality of chest compressions performed during cardiopulmonary resuscitation (CPR) in a moving environment. This study thus aimed to introduce a simple device that maintains the balance of a person performing CPR in a moving environment, such as an ambulance. We also sought to evaluate the effectiveness of this device in the improvement of the quality of chest compressions.

METHODSThe experiment comprised a total of 40 simulated cardiopulmonary arrest scenes (20 in the experimental group and 20 in the control), in which CPR was conducted by eight paramedics. Each simulation involved two paramedics randomly selected from the eight. The ambulance took the same route from the simulated site to the hospital, and continuous CPR was performed on a manikin in the ambulance with or without the aid of our proposed novel device.

RESULTSThe average number of chest compressions per simulation in the experimental and control groups was 1330.75 and 1266.60, respectively (p = 0.095). The percentage of chest compressions with adequate depth achieved in the experimental and control groups was 72% ± 4% and 50% ± 3%, respectively (p < 0.0001).

CONCLUSIONBy maintaining the balance of the CPR performer, our proposed novel device can offset the negative impact that instability (due to a moving environment) has on chest compressions. The device may also lead to an increase in the percentage of chest compressions that achieve adequate depth.

Adult ; Allied Health Personnel ; Ambulances ; Cardiopulmonary Resuscitation ; instrumentation ; methods ; Emergency Medical Services ; methods ; Equipment Design ; Equipment Safety ; Female ; Humans ; Male ; Manikins ; Movement ; Out-of-Hospital Cardiac Arrest ; mortality ; therapy ; Physical Exertion ; physiology ; Reference Values ; Risk Assessment ; Sensitivity and Specificity ; Survival Rate ; Treatment Outcome

Isokinetic technology in testing and training is the most advanced practical technique in the evaluation of muscle function. This method is a continuous dynamic test in the full range of the joint motion which has strong pertinence at the aspect of assessing muscle strength, and is an objective and quantitative method for reflecting each point's muscle strength in the range of the joint motion. This article reviews the key concepts, brief history of development and influencing factors of isokinetic technology in testing and training, introduces the progress in the field of rehabilitation medicine and sport science, etc., and discusses the future exploration in forensic science.
Biomechanical Phenomena ; Forensic Medicine/methods* ; Humans ; Isometric Contraction/physiology* ; Joints/physiopathology* ; Muscle Contraction/physiology* ; Muscle Strength/physiology* ; Muscle Strength Dynamometer ; Muscle, Skeletal/physiopathology* ; Physical Education and Training/methods* ; Physical Exertion ; Physical and Rehabilitation Medicine ; Posture ; Range of Motion, Articular/physiology* ; Sports Medicine ; Wounds and Injuries/rehabilitation*

Respirator breathing resistance impacts performance of wearers during constant work load. However, it is less clear as to how breathing resistance affects the tolerant capacity of users during graded work load. The present study investigated the tolerant capacity of 8 individuals during incremental work load. The 8 subjects were required to wear two matched respirators (respirators I and II which were designed to have different breathing resistances and the same dead space) respectively on separate days and then work to end points. Minute ventilation (V(E)), breathing frequency (BF), oxygen consumption (VO(2)) and heart rate (HR) were recorded during exercise, while tolerant time, response time and breathing discomfort were measured at the end of each test trial. The test variables were compared between the two respirators by using matched-pairs t-test. The results showed that the tolerant time was significantly reduced for the respirator I with higher level of breathing resistance when compared with its counterpart with lower breathing resistance (respirator II) (P<0.05). The same changes occurred for response time. Results also showed a significant increase in V(E) and BF for respirator I wearers when the work load was above 125 W. The O(2) consumption was similar under the two breathing resistance conditions. These findings suggested that the respiratory resistance caused by self-contained breathing apparatus (SCBA) has an impact on the tolerant capacity of users.
Airway Resistance ; physiology ; Exercise ; physiology ; Exercise Tolerance ; physiology ; Humans ; Male ; Oxygen Consumption ; physiology ; Physical Exertion ; physiology ; Respiration, Artificial ; methods ; Respiratory Mechanics ; physiology ; Young Adult

The present study was aimed to explore the changes of phosphorylated AMP-activated protein kinase (pAMPK) level in skeletal muscle after exposure to acute hypobaric hypoxia and exhaustive exercise. Thirty-two male Sprague-Dawley (SD) rats were randomly divided into sea level and high altitude groups. The rats in high altitude group were submitted to simulated 5 000 m of high altitude in a hypobaric chamber for 24 h, and sea level group was maintained at normal conditions. All the rats were subjected to exhaustive swimming exercise. The exhaustion time was recorded. Before and after the exercise, blood lactate and glycogen content in skeletal muscle were determined; AMPK and pAMPK levels in skeletal muscle were detected by Western blot. The results showed that the exhaustion time was significantly decreased after exposure to high altitude. At the moment of exhaustion, high altitude group had lower blood lactate concentration and higher surplus glycogen content in gastrocnemius compared with sea level group. Exhaustive exercise significantly increased the pAMPK/AMPK ratio in rat skeletal muscles from both sea level and high altitude groups. However, high altitude group showed lower pAMPK/AMPK ratio after exhaustion compared to sea level group. These results suggest that, after exposure to acute hypobaric hypoxia, the decrement in exercise capacity may not be due to running out of glycogen, accumulation of lactate or disturbance in energy status in skeletal muscle.
AMP-Activated Protein Kinases ; metabolism ; Altitude ; Animals ; Computer Simulation ; Glycogen ; metabolism ; Hypoxia ; physiopathology ; Lactic Acid ; blood ; Male ; Motor Activity ; physiology ; Muscle, Skeletal ; enzymology ; metabolism ; Phosphorylation ; Physical Exertion ; physiology ; Rats ; Rats, Sprague-Dawley

The present study was aimed to investigate the effect of hypoxic training on mitochondrial antioxidants and activities of respiratory chain complexes in mitochondria of skeletal muscle in rats. Forty healthy male Wistar rats were randomized to 5 groups (n=8): living low-training low (LoLo), living high-training high (HiHi), living high-training low (HiLo), living low-training high (LoHi), and living high-exercise high-training low (HiHiLo). All the animals were subjected to 5-week training in normoxic (atmospheric pressure=632 mmHg, altitude of about 1 500 m) or hypoxic environment (atmospheric pressure=493 mmHg, simulated altitude of about 3 500 m). Before exhaustive running, the animals stayed in normoxia for 3 d. Skeletal muscles were prepared immediately after exhaustive running. Muscle mitochondria were extracted by differential centrifugation. Spectrophotometric analysis was used to evaluate activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), catalase (CAT), malondialdehyde (MDA) level and respiratory chain complex (C) I-III activities in muscle homogenate and mitochondria. Results showed that SOD, GSH-Px, CAT activities and MDA level in skeletal muscle homogenate in HiHi and HiHiLo groups were significantly increased (P<0.05 or P<0.01) compared with those in LoLo group. Muscle mitochondrial MDA level in HiHi and HiHiLo groups was significantly lower (P<0.01), while activities of SOD, GSH-Px and CAT were remarkably higher (P<0.01) than those in LoLo group. Meanwhile, C I-III activities in HiHi and HiHiLo groups were increased significantly (P<0.01), and C II activity in HiLo group also was increased remarkably (P<0.01) compared with those in LoLo group. These results suggest that HiHiLo might be an ideal hypoxic training mode.
Adaptation, Physiological ; physiology ; Altitude ; Animals ; Antioxidants ; metabolism ; Electron Transport Complex I ; metabolism ; Glutathione Peroxidase ; metabolism ; Hypoxia ; metabolism ; physiopathology ; Male ; Mitochondria, Muscle ; metabolism ; Muscle, Skeletal ; metabolism ; physiology ; Physical Exertion ; physiology ; Rats ; Rats, Wistar ; Superoxide Dismutase ; metabolism

OBJECTIVETo study the dynamic changes of serum CK, CK-MB and myocardium histomorphology in different time periods after single bout and repeated exhausted exercise in rats.

METHODSThe animal models of myocardial injury were established by exhausted swimming. Creatine kinase (CK), creatine kinase mass (CK-MB) activities in serum were measured immediately at 3, 6, 12, 24, 48 and 96 hours after exhausted exercise, and the dynamic changes of myocardial histopathology were examined.

RESULTSThe CK, CK-MB activities were significantly increased immediately at 3, 6, 12 hours and peaked at 6 hours after single bout of exhausted exercise, meantime the degree of inflammatory cell infiltrate and strong acidophil staining were gradually increased in myocardium of rat, and the myocardial injury was most severe at 12 hours. After 1-week consecutive daily exhausted swimming, CK, CK-MB in serum were obviously increased immediately at, 3, 6, 12, 48 and 96 hours postexercise and peaked immediately and at 96 hours respectively postexercise. There were different degrees of myocardial injury in different time of recovery phase, and was most severe at 48 hours postexercise.

CONCLUSIONThe myocardial injury was induced by excessive exercise and/or exhausted exercise, and the resulting delayed-onset myocardial injury was further certified.

Animals ; Creatine Kinase ; blood ; Creatine Kinase, MB Form ; blood ; Fatigue ; blood ; Male ; Myocardium ; pathology ; Physical Exertion ; physiology ; Rats ; Rats, Wistar ; Swimming ; physiology

OBJECTIVETo investigate the metabolic changes of mice serum after loaded swimming and to provide a basis for the study of anti-fatigue functional food.

METHODSThe male Kunming mice were randomly divided into four group, fed an AIN-93 diet for 14 days, and forced to swim for 30, 60 or 120 min, respectively, with a load on their tails. The mice were executed after swimming immediately and the changes of serum metabolic profiles were analyzed using metabolomic approach. The spectrum was acquired by using Carr Purcell Meiboom Gill (CPMG) or Longitudinal Eddy Current Delay (LED) sequence, and transformed into 1H NMR spectrogram via Fourier transformation. All the data were analyzed by principal component analysis by using the SIMCA-P+ software.

RESULTSThe serum metabolic profiles changed significantly after loaded swimming. Serum beta-hydroxybutyric acid, acetate, lactate, lipid were increased and glucose, choline, phosphorylcholine, alanine and phosphatidylcholine decreased. These changes were time dependent.

CONCLUSIONThe changes of serum metabolic profiles after loaded swimming were time dependent, especially for lipid metabolite.Further study based on the interaction of choline and lipid metabolism may contribute to understand the mechanism of fatigue.

Animals ; Choline ; metabolism ; Fatigue ; blood ; metabolism ; physiopathology ; Lipid Metabolism ; Male ; Metabolome ; Mice ; Physical Exertion ; physiology ; Swimming ; physiology

OBJECTIVETo assess the effect of oxidative stress in development of acute high altitude response (AHAR) during the process of strong physical work at high altitude and its change after return to lower altitude.

METHODSNinety-six officers and soldiers of rapid entering into high altitude (3 700 m) with strong physical work were analyzed, all subjects were male, aged 18-35 years. According to the symptomatic scores of AHAR were divided into 3 groups: severe AHAR (group A, n = 24), mild AHAR (group B, n = 47) and without AHAR (group C, n = 25). Levels in serum 8-iso prostaglandinF2alpha(8-iso-PGF2alpha), superoxide dismutase (SOD) and malonaldehyde (MDA) were measured at higher altitude stayed 50 d and after return to lower altitude (1 500 m) 12 h and 15 d, and 50 healthy volunteers (group D) at 1 500 m altitude served as controll.

RESULTSLevels of serum 8-iso-PGF2alpha and MDA [(9.53 +/- 0.47) microg/L, (8.91 +/- 0.39) micromol/L] were significantly higher in group A than those in group B [(8.34 +/- 0.42) microg/L, (7.31 +/- 0.32) micromol/L] , group C [(7.02 +/- 0.48) microg/L, (6.41 +/- 0.23) micromol/L] and group D [(5.13 +/- 0.56) microg/L, (5.48 +/- 0.33) micromol/L], (all P < 0.01), and serum SOD [(52.08 +/- 3.44) micro/ml] was significantly lower in group A than that in group B [62.27 +/- 2.54) micro/ml], group C [(71.99 +/- 3.35) micro/ml] and group D [(80.78 +/- 3.44) micro/ ml] (all P < 0.01), there were significant differences between group B and C, C and D (all P < 0.01). At altitude 3 700 m 50 d, AHAR scores was positively correlated with serum 8-iso-PGF2alpha and MDA (all P < 0.01), negatively correlated with SOD (P < 0.01). Serum 8-iso-PGF2alpha and MDA were negatively correlated with SOD (all P < 0.01). Levels of serum 8-iso-PGF2alpha and MDA were significantly higher at altitude of 3 700 m 50 d than those at altitude of 1 500 m 12 h,15 d in group D (all P < 0.01), and serum SOD was significantly lower than that at 1 500 m 12 h,15 d in group D (all P < 0.01), there were significantly difference between at 1 500 m 12 h and 15 d (all P < 0.01), there were no difference between at 15 d in group D (all P > 0.05).

CONCLUSIONThe more serious of oxidative stress and oxidative/antioxidative imbalance, the more serious of AHAR, oxidative stress and oxidative/antioxidative imbalance may be involved in the development of AHAR. The changes were obviously improved after return to lower altitude 12 h, and recovered to normal after 15 d.

Adolescent ; Adult ; Altitude ; Altitude Sickness ; physiopathology ; Humans ; Male ; Oxidative Stress ; physiology ; Physical Exertion ; physiology ; Young Adult