Adolescent ; Exercise Tolerance ; physiology ; Female ; Humans ; Male ; Oxygen Consumption ; physiology ; Swimming ; physiology ; Young Adult

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

AIMTo observe the effects of different periods of exercise on the iron status.

METHODSFemale rats were randomly divided into 3-, 6-, 12-month swimming exercise groups and their corresponding sedentary groups. The hematological indices of iron status and the non-heme iron (NHI) and total NHI (TNHI) of the organs were determined at the end of the desired period.

RESULTSAs compared with the corresponding sedentary groups, plasma iron and transferrin-iron saturation of three exercise groups were decreased without significant changes of blood hemoglobin and hematocrit. The NHI contents and TNHI of the liver, spleen and kidney were decreased. Although the NHI contents of the heart decreased, TNHI was not significantly changed. TNHI of the organs in both the exercised and sedentary rats were found to increase with age.

CONCLUSIONThe exercise-induced low iron status with depleted iron storage is similar to the iron-deficiency status, but it could not be explained using the hypothesis of iron deficiency. Both the NHI redistribution and the maintained iron storage suggests the adaptation of low iron status to exercise. Therefore, the so-called exercise-induced iron deficiency could not exist.

Animals ; Female ; Hematocrit ; Iron ; deficiency ; metabolism ; Physical Conditioning, Animal ; physiology ; Rats ; Rats, Sprague-Dawley ; Swimming ; physiology

To investigate the effect of treadmill running on the ability of learning in young rats, male Sprague-Dawley rats (5 weeks of age) were used for the experiment. Animals were randomly divided into the control and running groups (n=15 in each group). The rats in running group were made run on a motor-driven treadmill for 1 week at a speed of 2 m/min for the first 5 min, at a speed of 5 m/min for the next 5 min, then at a speed of 8 m/min for the last 20 min. Then the Morris water maze was used to observe learning and memory ability of rats in both groups. The tests consisted of place navigation and spatial probe test. We found that, in place navigation training, the latency of rats in running group was less than that in control group (P<0.05); and from the third training session on, there was significant difference between the rats in control and running groups in swimming velocity (P<0.01); furthermore, it was observed that the rats in running group had stronger motivation and more exact orientation in searching for platform, which could be indicated by the index of turn angle and angular velocity. In spatial probe test, there was no significant difference between the two groups in swimming velocity, percentage of swimming distance and frequency of crossing platform in D quadrant, where the platform situated (P>0.05). These findings suggest that low speed treadmill running can enhance the ability of learning in young rats.
Age Factors ; Animals ; Male ; Maze Learning ; physiology ; Memory ; physiology ; Physical Conditioning, Animal ; physiology ; Rats ; Rats, Sprague-Dawley ; Spatial Behavior ; physiology ; 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

Age Factors ; Aging ; immunology ; physiology ; Animals ; Lymphocyte Activation ; immunology ; Male ; Physical Conditioning, Animal ; physiology ; Random Allocation ; Rats ; Rats, Sprague-Dawley ; Swimming ; physiology ; Thymus Gland ; immunology

AIMThe purpose of the present study is to discuss the influence of different exercise load on the concentration of ET in plasma and myocardial cells, and the activity of ETR on myocardial cell's membrane in rats.

METHODS45 male SD rats were divided into the following 5 groups randomly: Group A (control group); Group B (45 min swim group); Group C (90 min swim group); Group D (150 min swim group); Group E (acute exhaust group). After having been trained for 8 weeks, the levels of ET and activity of ETR were measured by RIA.

RESULTSThe concentrations of ET in plasma and myocardial cells of 90 min swim group were decreased significantly (P < 0.01)and 90 min swim could reduce the activity of ETR (P < 0.01). The activity of ETR was elevated significantly in 150 min swim group (P < 0.01).

CONCLUSIONModerate exercise loads can significantly ameliorate the cardiovascular function, and high exercise loads is harmful to myocardial cells.

Animals ; Endothelin-1 ; metabolism ; Male ; Myocytes, Cardiac ; metabolism ; Physical Conditioning, Animal ; physiology ; Rats ; Rats, Sprague-Dawley ; Receptor, Endothelin A ; metabolism ; Swimming

AIMTo investigate the effects of CoQlo supplementation on liver mitochondrial function and aerobic capacity in adolescent athletes.

METHODSBased on a single blinded study design, 18 male adolescent swimming athletes were randomized into two groups, supplement CoQ10 100 mg/d (Q group), or placebo (P group) for 28 days respectively.

RESULTS(1) After supplementation, the plasma CoQ10 concentration in Q group was significantly elevated and significantly higher compared to P group. (2) After supplementation, the rest plasma MDA level in Q group remained unchanged and was significantly lower compared to P group. (3) The plasma CoQ10 concentration of the 18 athletes was significantly decreased during the first constant endurance exercise. (4) The baseline plasma CoQ10 of the 18 subjects showed significantly positive correlation with VO2max measured in the first incremental exercise. (5) No significant difference of increased level of AKBR between Q group and P group. (6) No significant difference of increase level of VO2max, individual lactate threshold and exercise economy between Q and P group.

CONCLUSIONAlthough there is an increased demand for plasma CoQ10 during endurance exercise and CoQ10 supplement can depress lipid peroxidation, there is no effect of CoQ10 supplementation on liver mitochondrial function and aerobic capacity in adolescent athletes.

Adolescent ; Exercise ; Humans ; Lipid Peroxidation ; Male ; Mitochondria, Liver ; metabolism ; physiology ; Physical Endurance ; Swimming ; Ubiquinone ; administration & dosage ; analogs & derivatives

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 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