PO-092 Effects of hypoxic exercise on weight loss and lipid metabolism in overweight/obese men

Objective  In recent years, people's diet has undergone tremendous changes. Excessive energy intake combined with insufficient exercise has made obesity a serious social problem. This study aims to achieve different training conditions under hypoxia and normoxia，conducting a six-week exercise training for obese overweight people. Comparing the difference in exercise weight loss between obese and overweight people in the normoxia training environment compared with hypoxia intervention, and the effect of hypoxic intervention on lipid metabolism indicators in overweight and obese people. Methods  A total of 40 male overweight/obese subjects were enrolled in the study, aged 18-47 years, with no abnormal physical examination and no motor contraindications. The overweight standard is BMI≥24, and the obesity standard is BMI≥28.All subjects were randomly matched according to body weight, divided into hypoxia group and normoxia group, and exercised for 6 weeks, training 3 times a week, one time every two days. Sports training includes 30 minutes of strength training and 30 minutes of aerobic endurance training. There are 5 minutes of warm-up and finishing activities before and after training. The strength training tool is dumbbell, and the weight of the corresponding 12RM is selected according to the exercise ability of the subject, and 8 exercises are performed. They are dead lift, upright row, squat, shoulder press, calf Jump, advance lunge, biceps curl and triceps extension. Those 8 movements are divided into two small loop trainings, which complete two large groups (each small loop is completed twice).Aerobic endurance training is done using a treadmill with a slope of 0°and the speed is adjusted according to the range of the target heart rate. The target heart rate is 60%-70% at the maximum heart rate. The maximum heart rate calculation method is (220-age).The hypoxic group is equipped with a suction-type atmospheric hypoxic device and is operated under a low-oxygen environment. The oxygen content of the inhaled mixed gas is 16%, the normoxic group was exercised under normoxic conditions. Nutritional education was given to all subjects prior to the start of exercise intervention, but diet was not restricted during the intervention. Before and after intervention, height and weight were measured, and BMI was calculated. Fasting venous blood was used to detect total cholesterol (TC), total triglyceride (TG), high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein cholesterol (LDL-C), leptin (LEP) and adiponectin (ADPN). All test results are expressed as mean ± standard deviation. Comparison of data between groups, using nonparametric Mann-Whitney U test. Comparison of intra-group data, using non-parametric Wilcoxon matching for symbol level checking, the significance level was P<0.05, and the very significant level was P<0.01. Results (1) After the intervention, the body weight of both groups decreased, and the Δbody weight (P<0.01), body weight change rate (P<0.01) and BMI change rate (P<0.01) in the hypoxic group were significantly higher than normal oxygen group. (2) TG, TC and LDL-C decreased in the hypoxic group, and there was a significant difference between TG and TC before intervention (P<0.01). There was no significant difference in TG, TC and LDL-C between the normoxic group and the intervention group (P>0.05). (3) The TG change rate (P<0.05), TC change rate (P<0.05) and LDL-C change rate (P<0.01) in the hypoxic group were significantly higher than those in the normoxic group. (4) HDL-C in hypoxia group and normoxia group decreased after intervention, and there was no significant difference between the two groups (P>0.05), and there was no difference between HDL-C(P>0.05). (5) LEP and ADPN in the hypoxic group increased after intervention, but there was no significant difference compared with before intervention (P>0.05). LEP and ADPN in the normoxic group decreased after intervention, and there was no difference between the LEP change rate and the ADPN change rate (P>0.05). Conclusions Under hypoxic intervention, the weight change, rate of change, and BMI change rate of overweight people were larger than those of the normoxic group. Body weight, BMI is a direct indicator of the degree of obesity in individuals. The hypoxic weight loss intervention shows greater advantages than the normoxic group from the intuitive data, which can help overweight and obese people to lose more weight under the same training load and intensity. After six weeks of training, in the hypoxic group, TC, TG and LDL-C decreased, and HDL-C increased. However, in the normoxic control group, these indicators did not show similar significant changes. It shows that through hypoxia intervention combined with exercise training, it can prevent and alleviate various chronic diseases caused by obesity more effectively, such as atherosclerosis. The other two indicators, LEP and ADPN, did not change significantly in both hypoxic and normoxic training. Conjecture there may be other mechanisms affecting the expression levels of these two hormones in the body. In summary, the researchers think the hypoxic exercise to lose weight is better than normal oxygen exercise, and it has a greater impact on most lipid metabolism indicators, which can stimulate most lipid metabolism to produce benign changes

Comparative SNP and Haplotype Analysis Reveals a Higher Genetic Diversity and Rapider LD Decay in Tropical than Temperate Germplasm in Maize

Understanding of genetic diversity and linkage disequilibrium (LD) decay in diverse maize germplasm is fundamentally important for maize improvement. A total of 287 tropical and 160 temperate inbred lines were genotyped with 1943 single nucleotide polymorphism (SNP) markers of high quality and compared for genetic diversity and LD decay using the SNPs and their haplotypes developed from genic and intergenic regions. Intronic SNPs revealed a substantial higher variation than exonic SNPs. The big window size haplotypes (3-SNP slide-window covering 2160 kb on average) revealed much higher genetic diversity than the 10 kb-window and gene-window haplotypes. The polymorphic information content values revealed by the haplotypes (0.436–0.566) were generally much higher than individual SNPs (0.247–0.259). Cluster analysis classified the 447 maize lines into two major groups, corresponding to temperate and tropical types. The level of genetic diversity and subpopulation structure were associated with the germplasm origin and post-domestication selection. Compared to temperate lines, the tropical lines had a much higher level of genetic diversity with no significant subpopulation structure identified. Significant variation in LD decay distance (2–100 kb) was found across the genome, chromosomal regions and germplasm groups. The average of LD decay distance (10–100 kb) in the temperate germplasm was two to ten times larger than that in the tropical germplasm (5–10 kb). In conclusion, tropical maize not only host high genetic diversity that can be exploited for future plant breeding, but also show rapid LD decay that provides more opportunity for selection

Streamwise vortices in hypersonic flow on a compression ramp

Compression ramp flows with a free-stream Mach number of 7.7 are numerically studied to uncover the physics beneath the experimentally observed phenomena. This work focuses on laminar SWBLI with a moderate flow separation. Direct numerical simulations (DNS) are performed to investigate the characteristics of the streamwise vortices and surface heat flux streaks occurring in the compression ramp flow. Excellent agreements between the DNS results and experimental data as well as theoretical predictions are achieved. The finite-span effects encountered in experiments are also examined. The DNS results demonstrate the occurrence of streamwise vortices and heat flux streaks in compression ramp flows in the absence of external disturbances. Additionally, the presence of surface heat flux streaks leads to a considerable surface heat transfer enhancement downstream of reattachment. The influence of free-stream Reynolds number and ramp angle on the features of the streamwise vortices and streaks are analysed in detail and compared with experimental measurements. Another important finding of this dissertation is the flow unsteadiness triggered by the intrinsic instability in the separation bubble. In the fully developed flow, the surface heat flux downstream of reattachment exhibits a broadband low-frequency unsteadiness, which propagates in streamwise direction. Moreover, the unsteadiness of surface heat flux streaks is coupled with a pulsation of the reattachment position. By conducting a dynamic mode decomposition analysis, several oscillatory modes characterised by streamwise low-frequency periodicity are revealed in the separation bubble flow. This flow structure originates from the instability of the separation bubble flow and is linked to the downstream reattached flow by the shear layer above the bubble. To evaluate the centrifugal instability resulting from the local streamline curvature near reattachment, the Görtler number for a compression ramp flow is accurately determined via different methods. The first one gives the variation of the Görtler number near reattachment on the basis of the DNS data. Additionally, based on a simplified physical model, a formula depending only on the flow conditions and the geometry of compression ramp is deduced to predict the Görtler number. Furthermore, it is found that the Görtler number increases with increasing ramp angle and unit Reynolds number, and it decreases with increasing Mach number and wall-to-stagnation temperature ratio

Flatness measurement of large flat with two-station laser trackers

We present a novel method to accurately measure the flatness of a large flat. The method can be seen as a task-specific error correction of the laser tracker. Laser trackers are positioned at two specific measuring stations and measure the coordinates of the same sample points. The angular errors of the primary laser tracker are compensated with constraint information provided by an additional laser tracker. Using this method, we measure the flatness of a 4.5 m flat. The flatness measurement uncertainty is 1.4 µm in rms (root mean square)

Carrier fringe method of moiré interferometry for tiny strain measurements in micro-field

In this paper, we demonstrate a new optical method for tiny strain measurements based on the principle of carrier fringes of moir, interferometry. A cross-line grating with frequency of 1200 lp/mm is replicated on the specimen surface, and the strain can be deduced from the changes in carrier fringes before and after the deformation of an object. Four coherent laser beams are used to obtain the carrier fringe patterns of field U and V. Both theoretical analysis and numerical simulation indicate that the ideal accuracy of strain can be controlled within a range of +/- 1 mu I mu. Case study of a plane extension experiment shows that the measurement accuracy of strain can be controlled within the range of +/- 10 mu I mu. The average strain values of every row of field U and every column of field V can be obtained by using this method, and approximated strain of every pixel in the whole-field can be further acquired, and thus it is possible to measure tiny strains occurred in a micro-field. The technology in this paper can provide comprehensive information for analyzing related mechanical content in the field of MEMS