Objective To explore the effect of training weights on energy expenditure(EE)among young males during squatting.Methods Twenty young males with strength training experience≥1 year were recruited and performed 3 sets of squats,with 5 repetitions per set,at 40%1RM,60%1RM and 80%1RM,respectively,with an interval of at least 72 hours.Oxygen uptake(VO2),heart rate,blood lactate,and the mechanical work on the barbell during squat exercises were measured before,during,and after each sets.Moreover,one-way repeated-measures ANOVA was used to compare EE differenc-es between different training weights,and two-way ANOVA was employed to examine the weight×method effect on metabolic equivalent(MET)values.Meanwhile,Pearson's correlation analysis was conducted to examine the correlation between EE and barbell mechanical work.Results(1)Training weight has significant effects on the total energy expenditure and EE during excess post-exercise oxy-gen consumption(EPOC)stage(P<0.001),while a significant increase was observed in the glycolytic EE only at 80%1RM and the aerobic EE with no less than 60%1RM(P<0.01 and P<0.05).(2)The percentage of EPOC-stage and glycolytic EE in the total energy expenditure was significantly higher than the aerobic EE(P<0.01),while that of aerobic EE at 40%1RM and 60%1RM was significantly higher than at 80%1RM(P<0.01).(3)Total energy expenditure(r=0.65,P<0.001)and EPOC-stage EE(r=0.68,P<0.001)showed moderate correlation with the mechanical work done.(4)Aerobic EE was significantly lower than the mechanical work done during squatting(P<0.001).Moreover,the MET values of squats calculated using aerobic EE during exercise at 40%-80%1RM was 2.42±0.54,2.89±0.87 and 2.7±0.56,while the MET ones calculated using the total energy expenditure reached 14.99±2.94,20.52±4.51 and 28.57±6.88.Conclusions Only EPOC-stage and glycolytic EE elevate with the increase of weight.Moreover,EE and the MET value scalculated using VO2 dur-ing exercise may under estimate the actual intensity of squat.Meanwhile,the accuracy of EE estima-tion may be improved by introducing the mechanical work.

OBJECTIVE:To conduct a Meta-analysis of evaluating the effects of whole-body vibration training on bone mineral density in postmenopausal women.METHODS:We searched CNKI,WanFang,PubMed,and Web of Science for studies on whole body vibration training to improve bone mineral density in postmenopausal women from database inception to April 3,2024,with the search terms whole-body vibration training,postmenopausal women,osteoporosis,and bone mineral density.Included indicators were lumbar spine(L1-L4,L2-L4),femoral neck,greater trochanter,Ward's triangle,and whole-body bone density.Revman 5.3 and R 4.3.3 were used for data analysis.RESULTS:(1)A total of 28 randomized controlled studies were included.(2)Vibration intensity:Vibration frequency＞20 Hz and amplitude＞2 mm could significantly increase the bone mineral density of the femoral neck,greater trochanter,Ward region,L1-L4 and L2-L4 lumbar vertebrae(P＜0.01,I2＞50％).(3)Training period and frequency:2-3 times per week,48-96 times per week,the bone mineral density at each site increased significantly(P＜0.05,I2＜50％).(4)Movement patterns:Dynamic training significantly increased bone mineral density in the femoral neck(P=0.03,/2=0％),greater trochanter(P＜0.001,I2=0％)and Ward region(P＜0.001,I2=0％);static squat significantly increased bone mineral density in L1-L4 lumbar spines(P＜0.001,I2=0％);and static multiple squatting was effective in improving bone mineral density in L2-L4 lumbar spines(P＜0.01,/2=0％)and the femoral neck(P=0.04,I2=34％).CONCLUSION:Whole-body vibration training has potential in improving bone mineral density in postmenopausal women.Recommended vibration frequencies and amplitudes are not less than 20 Hz and 2 mm,respectively,with no less than 48 training sessions.Static training is recommended for improving lumbar bone mineral density,while dynamic training is recommended for improving hip bone mineral density.

Objective To explore the effect of training weights on energy expenditure(EE)among young males during squatting.Methods Twenty young males with strength training experience≥1 year were recruited and performed 3 sets of squats,with 5 repetitions per set,at 40%1RM,60%1RM and 80%1RM,respectively,with an interval of at least 72 hours.Oxygen uptake(VO2),heart rate,blood lactate,and the mechanical work on the barbell during squat exercises were measured before,during,and after each sets.Moreover,one-way repeated-measures ANOVA was used to compare EE differenc-es between different training weights,and two-way ANOVA was employed to examine the weight×method effect on metabolic equivalent(MET)values.Meanwhile,Pearson's correlation analysis was conducted to examine the correlation between EE and barbell mechanical work.Results(1)Training weight has significant effects on the total energy expenditure and EE during excess post-exercise oxy-gen consumption(EPOC)stage(P<0.001),while a significant increase was observed in the glycolytic EE only at 80%1RM and the aerobic EE with no less than 60%1RM(P<0.01 and P<0.05).(2)The percentage of EPOC-stage and glycolytic EE in the total energy expenditure was significantly higher than the aerobic EE(P<0.01),while that of aerobic EE at 40%1RM and 60%1RM was significantly higher than at 80%1RM(P<0.01).(3)Total energy expenditure(r=0.65,P<0.001)and EPOC-stage EE(r=0.68,P<0.001)showed moderate correlation with the mechanical work done.(4)Aerobic EE was significantly lower than the mechanical work done during squatting(P<0.001).Moreover,the MET values of squats calculated using aerobic EE during exercise at 40%-80%1RM was 2.42±0.54,2.89±0.87 and 2.7±0.56,while the MET ones calculated using the total energy expenditure reached 14.99±2.94,20.52±4.51 and 28.57±6.88.Conclusions Only EPOC-stage and glycolytic EE elevate with the increase of weight.Moreover,EE and the MET value scalculated using VO2 dur-ing exercise may under estimate the actual intensity of squat.Meanwhile,the accuracy of EE estima-tion may be improved by introducing the mechanical work.

OBJECTIVE:To conduct a Meta-analysis of evaluating the effects of whole-body vibration training on bone mineral density in postmenopausal women.METHODS:We searched CNKI,WanFang,PubMed,and Web of Science for studies on whole body vibration training to improve bone mineral density in postmenopausal women from database inception to April 3,2024,with the search terms whole-body vibration training,postmenopausal women,osteoporosis,and bone mineral density.Included indicators were lumbar spine(L1-L4,L2-L4),femoral neck,greater trochanter,Ward's triangle,and whole-body bone density.Revman 5.3 and R 4.3.3 were used for data analysis.RESULTS:(1)A total of 28 randomized controlled studies were included.(2)Vibration intensity:Vibration frequency＞20 Hz and amplitude＞2 mm could significantly increase the bone mineral density of the femoral neck,greater trochanter,Ward region,L1-L4 and L2-L4 lumbar vertebrae(P＜0.01,I2＞50％).(3)Training period and frequency:2-3 times per week,48-96 times per week,the bone mineral density at each site increased significantly(P＜0.05,I2＜50％).(4)Movement patterns:Dynamic training significantly increased bone mineral density in the femoral neck(P=0.03,/2=0％),greater trochanter(P＜0.001,I2=0％)and Ward region(P＜0.001,I2=0％);static squat significantly increased bone mineral density in L1-L4 lumbar spines(P＜0.001,I2=0％);and static multiple squatting was effective in improving bone mineral density in L2-L4 lumbar spines(P＜0.01,/2=0％)and the femoral neck(P=0.04,I2=34％).CONCLUSION:Whole-body vibration training has potential in improving bone mineral density in postmenopausal women.Recommended vibration frequencies and amplitudes are not less than 20 Hz and 2 mm,respectively,with no less than 48 training sessions.Static training is recommended for improving lumbar bone mineral density,while dynamic training is recommended for improving hip bone mineral density.

AIM:To investigate the regulatory role of retinoid X receptor(RXR)in oxidative stress response of rat type Ⅱ alveolar epithelial cells(AECII)induced by hypoxia/reoxygenation(HR).METHODS:The AECII were di-vided into control(C)group,HR group,HR+solvent dimethyl sulfoxide(DMSO)group(HD group),HR+RXR agonist 9-cis-retinoic acid(9-RA)group(RA group),and HR+RXR antagonist HX531 group(HX group).Cell Counting Kit-8(CCK-8)method was used to measure the cell viability.Immunofluorescence staining was used to detect the expression of surfactant protein A(SP-A)and RXRα in AECII.Kits were detected to the levels of superoxide dismutase(SOD)and malondialdehyde(MDA)in cells.Transmission electron microscopy was used to observe the ultrastructural changes of the cells.Western blot was used to detect the protein level of nuclear factor E2-related factor 2(Nrf2).RT-PCR was used to detect the expression level of Nrf2 mRNA.RESULTS:Compared with C group,the cell viability and SOD activity in HR,HD,RA and HX groups were decreased significantly(P<0.05),the MDA content were increased significantly(P<0.05),the Nrf2 mRNA and protein expression levels were decreased significantly(P<0.05 or P<0.01),and the immuno-fluorescence expression of RXRα was significantly increased(P<0.01).Compared with HR and HX groups,the cells in RA group showed significantly increased cell viability(P<0.05),increased SOD activity(P<0.05),decreased MDA con-tent(P<0.05),increased Nrf2 mRNA and protein expression levels(P<0.01),and significantly increased immunofluo-rescence expression of RXRα(P<0.01).CONCLUSION:Hypoxia/reoxygenation can aggravate the oxidative stress re-sponse of rat AECII,and RXR agonist intervention can alleviate HR-induced rat AECII injury by inhibiting oxidative stress.