Increased non-oxidative and oxidative ATP production via metabolic pathways in skeletal muscle is essential for the maintenance of force and power production during exercise. However, substrate depletion and accumulation of metabolic byproducts are potential causes of fatigue. Reduced PCr availability can limit power production during sprint exercise, whereas carbohydrate depletion is a major limitation to endurance performance. During sprint exercise increased Pi and H+ may contribute to fatigue, and during prolonged strenuous exercise, the accumulation of NH3, reactive oxygen species, and heat can limit performance. Appropriate training programs and nutritional interventions are potential strategies to enhance fatigue resistance and exercise performance.

Lateral bending of the trunk has been specifically identified as a high risk factor for lower back disorders. However, few studies have presented in vivo kinematic data of the trunk while performing functional lateral bending tasks. Five healthy male subjects performed lateral lifting and lowering tasks under loading condition ranging from light (2kg) to 100% of a maximum (ML) at a controlled velocity. Single lowering tasks were also performed at 125% and 150% of ML. Video based movement analysis was used to determine kinematics of the trunk, pelvis, shoulders and neck in the frontal plane. Centre of pressure (COP) data was also obtained from a force platform on which the subjects stood when performing the lifting and lowering tasks. Kinematics of the trunk revealed a smooth and relatively large change in angular displacement (between 69°to 55°) toward the unloaded side during the lifting phase. Trunk angular displacement significantly decreased with increasing lifting load. The trunk was additionally divided into four segments representing the lower and upper lumbar regions and the lower and upper thoracic regions. The greatest displacement in these segments took place at the upper lumbar and lower thoracic regions (ranging from 29°to 22°and 23°to 17°, respectively) with the least displacement occurring in the lower lumbar and upper thoracic regions (approx. 6° and 5°, respectively). Both the upper lumbar and lower thoracic segments showed significant decreases in angular displacement with increasing load. During the single lowering trials the trunk rotated toward the loaded side with slightly less magnitude to that recorded during the lowering phase of the heaviest lifting and lowering conditions. Angular displacements of the upper lumbar and lower thoracic segments also decreased with increasing load in single lowering. Identified changes in the COP displacement were also correlated to increasing lifting and lowering load. The main findings of this study indicate that it is the central sections of the trunk that have the greatest motion during

Objective To make a survey of medication taken by Chinese athletes and a comparison between Chinese athletes and athletes from other countries in order to get information about how to improve Chinese athletes' performance. Method The information came from the forms"Doping Control Sample Collection" in which athletes answered the question: "What medications have you taken in the past 3 days?" The medicines taken by athletes were classified and statistically analyzed.Results 2,330 athletes and 25 kinds of sports were involved in. Medicines were statistically analyzed with 4 classes: profiling of declaration, vitamins and minerals, medicines for treatments, alternative medicine. Conclusion The survey recorded the types of supplements and medications taken by athletes in China in 1999. Chinese athletes took less vitamins and more alternative medicines than athletes from other countries.

Experimental, clinical and epidemiologic studies have provided strong evidence that physical training has beneficial effects on cardiovascular health. Numerous investigations have demonstrated that exercise increases coronary blood flow and myocardial perfusion. Importantly, training also can stimulate angiogenesis and accelerate collateral vessel growth in animal models with coronary artery occlusion. Cardiac adaptation such as increased vascularity or capillary density has been evidenced after regular endurance exercises. More recently, several studies indicate that physical training induces high levels of myocardial heat shock protein and antioxidant protein expression, which may play an important role in myocardial protection against ischemia-reperfusion injury.

Objective To explore the incidence and clinical characteristics of the anterior tibial translation(ATT) after anterior cruciate ligament injury.Methods One hundred and fifty-three patients with the anterior cruciate ligament injury underwent standard magnetic resonance imaging scans with full knee extension.Based on the relative location between the lateral tibial plateau and the lateral femoral condyle,all the patients were divided into an ATT positive group and an ATT negative group.Moreover,the posterior tibial slope angle(PTSA),the continuity of anterolateral ligament(ALL),and the integrity of posterior horn of the lateral meniscus of all the patients were detected so as to find the risking factors for ATT.Results Among the 153 patients,46 patients were finally confirmed to have ATT.Moreover,the average PTSA of the ATT positive group was significantly larger than that of the ATT negative group.However,there were no significant differences between the two groups in the continuity of ALL and the integrity of posterior horn of lateral meniscus.Conclusion In this study,the incidence of ATT was 30.1％,which may be correlated to the increased PTSA.

Objective To get a controllable acetabulum component inclination angle during the total hip arthroplasty(THA) with the lateral position,a new method using a self-made instrument was introduced.Methods Totally 80 consecutive patients undergoing THA at the lateral position were enrolled.Forty acetabular components were assembled using a new method with a self-made instrument referring to the 42 degrees' angle drawn on the wall(group A),while another 40 acetabular cups were implanted free-handedly(group B).The postoperative inclination angle was evaluated on the anterior-posterior pelvic radiographs.Results The average inclination angle was 43.3° ± 3.7°(34.7°～49.1°) in group A and 40.3 ± 4.5o(32.8°～50.7°) in group B.Moreover,40/40 of group A and 38/40 of group B were in the Lewinnek's inclination safe zone(P＞0.05),without significant differences between the two groups.Conclusion It is practical and reliable to decide the acetabular component orientation using the lateral position instrument and reference angle on the wall.

Objective To analyze the feasibility of using walking indicators to estimate other physical activity data,so as to provide evidences for the application of using walking monitoring tools to comprehensively assess the daily physical activity level.Methods Eighty participants were assessed 7 kinds of physical activities through wearing Cosmed K4b2 portable indirect calorimetry system and Actigraph GT3X accelerometer simultaneously.The indirect calorimetry was used as the criterion for measuring energy expenditure to develop individual equations using the vector magnitude (VM) as the independent variable.Then all participants were randomly divided into an experimental group(n=60) and a validation group (n=20).Omron HJ-113 pedometer and GT3X were then simultaneously worn to monitor their daily physical activities,with the wearing time of 3～4 days for the experimental group and 7 days for the validation group.Physical activity data were calculated using the individual equations.The correlation between walking indicators and the other physical activity data was analyzed in the experimental group,and the indicators of high correlation and application value were selected to develop equations to predict physical activity indicators.Then the data of the validation group were used to validate these equations.Results The correlation coefficients between daily steps and the moderate-to-vigorous physical activity(MVPA) time,MVPA volume,MVPA10 time and MVPA10 volume were 0.723,0.730,0.681 and 0.677 respectively(P＜0.01 for all).The correlation coefficient of the daily aerobic walking time to MVPA10 time and MVPA10 volume were 0.752 and 0.759 respectively(P＜0.01 for both).Six equations were developed based on these correlations(r2=0.55～0.63),and paired t test showed that there were no significant differences between the physical activity data predicted using these equations and the data measured by GT3X(P＞0.05).Moreover,Bland-Altman plot showed there was little predicted error for the 6 equations.Conclusion Walking indicators can indirectly reflect the overall physical activity level,and the equations developed in this study can be used to monitor the physical activity of larger samples.

Objective To investigate the effect of acute exercises of different intensities on the "browning" of epididymal white adipose tissue(WAT) in rats.Methods Thirty Sprague-Dawley male rats were randomly divided into a control group(C,n=6) and an exercises group(E,n=24).Rats in group E were further randomly divided into a moderate intensity exercise (EM,n=12,V=15 m/min) group and a high intensity intermittent exercise(EH,n=12,V=35 m/min,6min's exercises followed by 5 min's rest,repeating 3 times) group.Right after and 6 hours after the acute exercises,the epididymal WAT was taken,and the fibronectin type Ⅲ domain-containing 5 protein(FNDC5) and the uncoupling protein 1(UCP-1) mRNA were detected using RT-qPCR,while the level of FNDC5 and UCP-1 protein was evaluated using Western Blotting.Results Right after the acute exercises,compared with group C,the level of FNDC5 mRNA in group EH increased significantly (P＜0.01),while that of UCP-1 mRNA in group E decreased immediately(P＜0.05) but increased significantly six hours later(P＜0.05).Compared with group C,the level of FNDC5 in groups EM and EH tended to rise,and that of group EM increased significantly(P＜0.05).Compared with group C,the level of UCP-1 in group EM and EH had the tendency to rise,and it increased significantly immediately after exercises in group EH (P＜0.05).Conclusion The acute exercise at different intensities can promote the level of FNDC5 and UCP-1 in epididymal white adipose tissue,"browning" and heat production from fat issues.The level of UCP-1 mRNA increased significantly at 6 hours after exercises,while that of FNDC5 mRNA increased most immediately after the high-intensity intermittent exercises.

Objective To determine the effect of hypoxia conditions on the expression of autophagyrelated genes including P62,LC3 and Beclin-1 in the gastrocnemius muscles of rats with alimentary obesity and the possible mechanism of cellular autophagy induced by hypoxia exercises.Methods The model of rats with alimentary obesity was induced in Sprague-Dawley rats using high-fat diet.Then the obese rats were randomly divided into a control(C) group,a hypoxia-exercises-for-1-week(E1) group,a hypoxia-exercises-for-2-weeks (E2) group,a hypoxia-exercises-for-3-weeks (E3) group and a hypoxia-exercises-for-4-weeks(E4) group,each of 10.The rats were exposed to the environment where the simulated hypoxia was of about 13.6％ oxygen concentration(about the oxygen concentration at an actual altitude of 3,500 m),and underwent treadmill running with the speed at 20 m/min on a slope of 0 gradient every day,five days a week.After the last training,the rats were killed and sampled.The RT-PCR was used to detect the level of P62,LC3 and Beclin-1 mRNA and Western Blotting was conducted to examine the changes of protein P62 and LC3 before and after the intervention.Results Compared with group C,the expression of Beclin-1 mRNA in group E1,E2 and E3 increased significantly(P＜0.05),while the expression of protein Beclin-1 decreased significantly in group E2.The expression of protein Beclin-1 of group E2 and E3 was significantly lower than that of group E4,but there were no significant differences between group E2 and E3.Compared with group C,the relative expression of P62 mRNA in group E1 and E2 increased significantly(P＜0.05,P＜0.01),with that of group E2 significantly higher than group E1 (P＜0.05).Moreover,the relative expression of P62 mRNA in group E3 was significantly lower than that of E2(P＜0.01),and that of group E4 was significantly higher than group C,E1 and E3(P＜0.01).The relative expression of protein P62 in the obese rats in group E3 was significantly higher than that of group E2(P＜0.05).The relative expression of LC3 mRNA in group E2,E3 and E4 was significantly higher than that of group C(P＜0.01).Moreover,there were no significant differences in LC3-Ⅱ/LC3-Ⅰ protein among the five groups.Conclusion Hypoxia exercise can significantly enhance the relative expression of autophagy genes,and promote,to some extent,the autophagy.However,the transcription of autophagy genes does not happen synchronically with the synthesis of autophagy proteins.Moreover,an increase in autophagy in the skeletal muscle can be seen in the first two weeks of hypoxia exercises,followed by a gradual decrease with time prolonged,which may be the result of the gradual adaptation to hypoxia stimulation of the body.

Objective To discuss the effect of the electric stimulation on the free radicals and Nrf2 signaling pathway in skeletal muscle myoblasts(C2C12) of mice.Methods After 6 days of differentiation,skeletal muscle myoblasts(C2C12) cells of mice were randomly divided into a control group and an electrical stimulation group.The control group was not stimulated,while the electrical group was stimulated 30,45,60,75,90,120 and 150 minutes respectively with the electrical parameter as 20 ms,45 V and 5 Hz.The reactive oxygen species(ROS),glutathione peroxidase(GSH-Px) and nuclear factor E2 related factor 2(Nrf2) protein expression in C2C12 muscle tubes were determined.Results Compared with the control group,the amount of ROS produced in the C2C12 muscle tube increased significantly in the stimulation group(P＜0.05),except those stimulated for 30 and 150 minutes,with greatest increase for those stimulated for 60 and 120 minutes(P＜0.01).Compared with the control group,the activity of GSH-Px and the expression of Nrf2 nuclear protein increased significantly in all the stimula tion group(P＜0.05),except those stimulated for 30 minutes and with the greatest increase for those stimulated for 75 and 150 minutes(P＜0.01).Conclusion The electrical stimulation of 45 V,20 ms and 5 Hz can cause oxidative stress in the C2C12 muscle tube.Based on the variation of ROS production with the time of electric stimulation,it is found that only when ROS increases to a certain amount,can it activate the Nrf2 signaling system and related genes to make the GSH-Px play an antioxidant role.However,with the increase of stimulation time,the anti-oxidative ability decreases slightly,and then it continues to maintain its high level.