This study examined the regulatory effects of autonomic nervous system on aerobic endurance exercise performance in cold exposure, focusing on heart rate recovery (HRR) and heart rate variability (HRV) across genders. Thirty participants (17 males and 13 females) from a university track endurance program, classified as exercise grade II or above, underwent monitoring of HRV in time domain, frequency domain, nonlinear correlation indices and 1 min HRR. Measurements were taken before, during, and after aerobic endurance exercise in cold and normal environments, respectively. The results were as follows. (1) The duration of aerobic endurance exercise completed by all the subjects in cold environment was significantly increased compared with that in normal environment. The 1 min HRR after aerobic endurance exercise in cold environment was significantly lower than that in normal environment, and the decrease in the males was significantly higher than that in the females. (2) The time domain analysis results showed that, prior to the aerobic endurance exercise, there were no significant difference of standard deviation from the mean value of normal to normal intervals (SDNN), root mean square of successive differences (RMSSD), and percentage of adjacent normal-to-normal intervals differing by more than 50 ms (pNN50) between cold and normal environments. During aerobic endurance exercise in cold environment, SDNN, RMSSD and pNN50 were significantly higher than those in normal environment, with the females showing significantly greater increases compared with those of the males. The levels of SDNN, RMSSD and pNN50 in the males at different time points under different environments were significantly lower than those in the quiet state; The levels of SDNN and RMSSD of the females at different time points under different environments were significantly lower than those in the quiet state, while the pNN50 at different time points under cold environments was significantly lower than that in the quiet state. (3) Frequency domain analysis results showed that, prior to the aerobic endurance exercise, there was no significant difference of high frequency normalized units [HF (n.u.)], low frequency normalized units [LF (n.u.)] and LF/HF ratio between cold and normal environments. During aerobic endurance exercise in cold environment, the levels of HF (n.u.) significantly increased compared to normal environment in the females, while LF (n.u.) and LF/HF ratio levels significantly decreased compared to normal environments. The levels of HF (n.u.), LF (n.u.) and LF/HF ratio of different genders at different time points in the different environments showed no significant changes, compared to those in the quiet state. (4) Non-linear analysis results showed a significant increase in SD1 (standard deviation perpendicular to the line-of-identity)/SD2 (standard deviation along the line-of-identity) ratio during aerobic endurance exercise in cold environment in the females, while no significant changes were observed in the males. SD1/SD2 ratios in the males at different time points and in the females at 1 min under cold environments were significantly higher than those in the quiet state. These findings suggest that aerobic endurance performance increases during cold exposure, accompanied by gender-specific differences in the regulation of autonomic nervous system. Females exhibit higher vagal activity and faster autonomic nervous system recovery compared to males.
Humans ; Male ; Female ; Heart Rate/physiology* ; Cold Temperature ; Exercise/physiology* ; Physical Endurance/physiology* ; Autonomic Nervous System/physiology* ; Young Adult ; Adult ; Sex Factors

OBJECTIVE: To understand and analyze the rules of endurance exercise on the cerebral cortex adaptive mechanism in aged rats. METHODS: In this study, 3-month-old (n=20), 13-month-old (n=24) and 23-month-old (n=24) specific-pathogen free (SPF) male Sprague-Dawley Rat (SD) rats were divided into young (Y-SED), middle-aged (M-SED) and old-aged (O-SED) sedentary control group, and the corresponding Y-EX, M-EX and O-EX in the endurance exercise runner group. The 10-weeks of regular moderate-intensity aerobic exercise intervention were carried out in the endurance exercise runner group. The exercise mode is treadmill exercise (slope 0), and the exercise intensity gradually increases from 60%～65% of the maximum oxygen consumption (V·O) to 70%～75%, and the exercise time is 10 weeks. Hematoxylin and eosin (HE) staining was used to detect age-related morphological changes. The expressions of superoxide dismutase(SOD) and brain-derived neurotrophic factor (BDNF) and the expressions of synapsin 1 (SYN1) and Ca/calmodulin- dependent protein kinases IIα (CaMK IIα) / AMP-activated protein kinase α1(AMPKα1) / mammalian target of rapamycin (mTOR) pathway -related genes were detected. RESULTS: The cerebral cortex structure of the rats in each group showed age-related aging changes, the expression of SOD in the cortex showed a gradual decline, the expression of BDNF showed an age-increasing trend, and the expression levels of SYN1 and CaMK IIα were increased with age. The changes in AMPKα1 and SirT2 and IP3R, AKT1 and mTOR mRNA levels were increased slightly in middle-aged rats and decreased in aged rats. Compared with the rats in each sedentary control group, the nucleus of the cerebral cortex was tightly arranged and the number of nuclei observed under the microscope was increased significantly in each exercise group. Exercise promoted the expressions of SOD, BDNF and synaptophysin SYN1 in the cortex of rats, and the expression levels of SOD and BDNF in aged rats were up-regulated significantly (P＜ 0.01). The expression level of SYN1 in rats was up-regulated significantly (P＜0.05) in the young and aged rats. The expression of CaMK IIα in the cortex of middle-aged and aged rats was up-regulated (P＜0.01), while the expression level of CaMK IIα in young rats was down-regulated (P＜0.01). Exercise could up-regulate the expression level of AMPKα1 in the cortex of young rats (P＜ 0.05), but not in middle-aged and old-age rats. Exercise could up-regulate the expression of SirT2 in the cortex of rats in all age groups (P＜0.05). Exercise up-regulated the expression of phosphoinositide 3-kinase (IP3R)/ protein kinase B 1(AKT1) /mTOR in the cortex of rats, among which young IP3R was significantly up-regulated (P＜0.01) in the young group, mTOR was significantly up-regulated in young and middle-aged group (P＜0.01), and mTOR was also significantly up-regulated in the aged group (P＜0.05). CONCLUSION Endurance exercise up-regulates BDNF expression, regulates CaMKIIα signaling, activates AMPK signaling pathway and IP3R / AKT1 / mTOR signaling pathway, and improves synaptic plasticity in the cortex.
Age Factors ; Animals ; Cerebral Cortex ; physiology ; Male ; Neuronal Plasticity ; Physical Conditioning, Animal ; Physical Endurance ; Rats ; Rats, Sprague-Dawley ; Signal Transduction

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

Animals ; HSP70 Heat-Shock Proteins ; metabolism ; Male ; Physical Conditioning, Animal ; Physical Endurance ; physiology ; Quadriceps Muscle ; metabolism ; physiology ; Rats ; Rats, Sprague-Dawley ; Vascular Endothelial Growth Factor A ; metabolism

64 eight-week-old female rats were randomly divided into to 8 groups with four in medical treatment group and four in control group. The treatment groups were trained by progressive intensifying endurance swimming, and the medical-taken groups were fed with lycium for 5 weeks, and then the changes of the liver cellular free radical metabolism and ultrastructure were investigated. The effects of lycium and endurance training on liver cellular ultrastructure and free radical metabolism in rats were then explored. The results showed that exhaustive swimming time of rats could be extended by endurance training, and that exhaustive swimming time of rats could significantly be prolonged after taking lycium, and the ultrastructure of liver cell with taking lycium was more complete than that without taking lyceum. Lycium could cause significant increase of the activity of liver superoxide dismutase (SOD) and the ratio of SOD/MDA, and meanwhile cause decrease of the content of liver MDA. Conclusions can be drawn that lycium and endurance training can improve exercise capacity of rats, and lycium has certain protecting functions of the liver.
Animals ; Antioxidants ; metabolism ; pharmacology ; Drugs, Chinese Herbal ; pharmacology ; Female ; Free Radicals ; metabolism ; Liver ; metabolism ; ultrastructure ; Lycium ; chemistry ; Malondialdehyde ; metabolism ; Physical Endurance ; physiology ; Random Allocation ; Rats ; Rats, Wistar ; Superoxide Dismutase ; metabolism ; Swimming ; physiology

Heart Rate ; physiology ; Humans ; Male ; Physical Endurance ; physiology ; Physical Fitness ; physiology ; Resistance Training ; Young Adult

OBJECTIVEBased on high fat diet induced the model of atherosclerosis (AS) in C57BL/6J mice, authors studied the effect of endurance exercise on the atherosclerostic formation.

METHODSForty eight 8-week-old C57BL/6J mice were divided into four groups randomly (n=12): control (group N), 12-week atherosclerosis model group(group H), 12-week atherosclerosis model plus 11-week treadmill training group (group H + E) and 22-week atherosclerosis model group (group HS). Then, we observed the effects of endurance exercise on the ultra structure of aorta by electron microscope.

RESULTSTwenty weeks of high fat diet could result in serious AS in mice while endurance exercise could significantly antagonize or restrain the occur of AS. In addition, 10 weeks of endurance exercise could alleviate the symptom of pathological changes which already happened on aorta wall.

CONCLUSIONIt indicated that endurance exercise could effectively prevent and cure AS that induced by high fat diet.

Animals ; Aorta ; ultrastructure ; Atherosclerosis ; etiology ; prevention & control ; Diet, High-Fat ; adverse effects ; Dietary Fats ; administration & dosage ; Male ; Mice ; Mice, Inbred C57BL ; Physical Conditioning, Animal ; physiology ; Physical Endurance ; physiology

OBJECTIVETo study training effect of upper limbs and lumbar muscles in the proceed of air striking of straight punch by analyzing boxing athletes' changes of electromyogram (EMG).

METHODSWe measured EMG of ten women boxing athletes' upper arm biceps (contractor muscle), upper arm triceps (antagonistic muscle), forearm flexor muscle (contractor muscle), forearm extensor muscle (antagonistic muscle), and lumbar muscles by ME6000 (Mega Electronics Ltd.). The stipulated exercise was to do air striking of straight punch with loads of 2.5 kg of dumbbell in the hand until exhausted.

RESULTSIn the proceed of exercise-induce exhausted, the descend magnitude and speed of median frequency (MF) in upper limb antagonistic muscle exceeded to contracting muscle, moreover, the work percentage showed that contractor have done a larger percentage of work than antagonistic muscle. Compared with world champion's EMG, the majority of ordinary athletes' lumbar muscles MF revealed non-drop tendency, and the work percentage showed that lumbar muscles had a very little percentage of work.

CONCLUSIONAfter comparing the EMG test index in upper limb and lumbar muscle of average boxing athletes with that of the world champion, we find the testees lack of the training of upper limb antagonistic muscle and lumbar muscle, and more trainings aimed at these muscles need to be taken.

Boxing ; physiology ; Electromyography ; Female ; Humans ; Lumbosacral Region ; physiology ; Muscle, Skeletal ; physiology ; Physical Endurance ; physiology ; Resistance Training ; methods ; Upper Extremity ; physiology ; Young Adult

OBJECTIVETo study the suitable oxygen concentration in hypoxic preconditioning.

METHODSShort-term and long-term intermittent hypoxia modes were designed and the effects of various oxygen concentrations on body weight, blood oxygen saturation, swimming capability were analyzed.

RESULTSThe rate of body weight gain in rat model decreased gradually when exposed to hypoxia environment for long time. When the concentration of oxygen changed from 15% to 8%, accompanied with the decreasing of oxygen concentration, a platform was observed in blood oxygen saturation of rat model after hypoxic preconditioning training. Rat swimming capability improved significantly. After trained in 10% hypoxia environment, the swimming capability of kunming mice improved obviously.

CONCLUSIONProper level of hypoxic preconditioning training could improve hypoxia tolerance and enhance the rat sport capability significantly. 15%-10% oxygen concentration range could be regarded as a helpful effective area for hypoxic preconditioning, 10% oxygen concentration might be the eligible concentration for hypoxic preconditioning training.

Adaptation, Physiological ; physiology ; Animals ; Body Weight ; Hypoxia ; physiopathology ; Ischemic Preconditioning ; Male ; Oxygen ; analysis ; metabolism ; Physical Endurance ; physiology ; Rats ; Rats, Wistar

OBJECTIVETo evaluate the capability of C(N) and determinism% (DET%) together with the linear indices, we detected the surface electromyography (sEMG) signal changes during ramp contractions of biceps brachii.

METHODS5 seconds sEMG signals of 11 male volunteers were recorded to analyze its changes of the linear indices AEMG, mean power frequency(MPF), MF and the non-linear indices C (N), DET%.

RESULTSAverage electromyography (AEMG) inclined linearly from 112.14 microV to 1277.18 microV while DET% displayed an decrease from 74.95 to 46.7 during the 5 voluntary contractions. The spectrum parameters MPF/MF and C(N) leveled off with the increasing of the force.

CONCLUSIONThe linear index AEMG inclined linearly while MPF and MF leveled off with the increasing of the force. The non-linear index DET% declined while C(N) leveled off during the 5 seconds ramp contractions.

Adolescent ; Adult ; Arm ; Biomechanical Phenomena ; Electromyography ; Humans ; Male ; Muscle Contraction ; physiology ; Muscle Fatigue ; physiology ; Muscle, Skeletal ; physiology ; Physical Endurance ; Young Adult