Objective To understand the characteristics of surface electromyography (sEMG)of vastus medialis muscle fatigue induced by isokinetic flexion and extension movement, and to further provide references for the application of sEMG on dynamical movements.Methods Arial isokinetic equipment and ME6000 equipment were combined to analyze the time domain indices including root mean square (RMS ) integrated electromyography (iEMG)and spectrum indices including median frequency (MF)and mean power frequency (MPF)for vastus medialis from ten students from Shenyang Sport University during isokinetic fatigue.Results During the isokinetic muscle fatigue the RMS and iEMG were significantly increased (P<0.05),accompanying with higher effect sizes for iEMG than for RMS. As for the spectrum indices,MF and MPF were significantly decreased (P<0.05)with larger effect sizes for MPF than for MF. The increase rate of iEMG was significantly higher in iEMG than RMS (P<0.05),and the decline rate of MPF was larger than MF (P<0.05).Conclusion The iEMG as a time domain index and MPF as a spectrum index can be sensitive indexes to assess the dynamic muscle fatigue.

Objective To establish a simple and practical regression equation for estimating maximal oxygen uptake(VO2max),so as to provide a base and reference for epidemiological studies.Methods Totally 128 freshmen(88 males and 40 females) were randomly recruited majoring in social sports and physical education to conduct the correlation analysis between VO2max and the weight,body surface area,body mass index(BMI) and vital capacity.Then 34 freshmen(17 males and 17 females) were chosen from them randomly to compare whether there was a significant difference between the two VO2max relative values measured by Astrand estimation and direct measurement respectively.Based on the results,the multiple linear regression analysis was conducted:independent variables entered theregression equation in turn according to the Forward method and the significance test of the regression equation,the regression coefficients and the fitting degree was conducted.We got the regression equation finally according to the Durbin-Watson and VIF values.Another 17 male freshmen were recruited to verify the efficient of the regression equation.Results Significant differences were observed in the relative VO2max value of females,being 45.14 ± 8.08 ml/kg/min and 32.63 ± 5.87 ml/kg/min by Astrand and direct measuring respectively,but not in that of the male,being 47.24 ± 6.46 ml/kg/min and 51.62 ± 6.91 ml/kg/min accordingly.There was very significant correlation between VO2max and weight,body surface area,BMI and vital capacity of the male freshmen(P＜0.01),but not of the female freshmen (P＞0.05).The regression equation of estimating the relative VO2max of the boy freshmen was y=34.812+0.015×vital capacity(ml)-40.403×body surface area(m2).No significant differences were found between the value calculated using this equation and that measured directly (P＞0.05).Conclusions The regression equation found in this study is simple,practical and efficient,and it can be used to estimate the relative VO2max of male freshmen majoring in physical education and social sports in epidemiologic study,so as to evaluate their cardiopulmonary fitness.

This article summarizes and organizes relevant publications in journals, along with a review of medical history, systematically summarizing the development process of dental alveolar surgery in China. The initial establishment phase (1935—1952) marked the starting point of Chinese Alveolar Surgery. Despite the impact of wars, it laid the foundation for subsequent research and practice. During the early development phase (1953—1966), the "Chinese Journal of Stomatology" was founded, which promoted the development of Alveolar Surgery. Research focused on tooth extraction methods and complications. Tooth Transplantation and Preprosthetic Surgery gradually began to take off. The stagnant phase (1967—1977) occurred due to the interruption of international exchanges, leading to an almost complete halt in the development of Alveolar Surgery. Entering the rapid catch-up phase (1978—1985), Alveolar Surgery scholars in China began striving to overcome the stagnation of the previous decade. While some progress was made, no significant innovative achievements emerged. In the scientific development phase (1986—2010), clinical research, basic experiments, and paper writing in modern Chinese Alveolar Surgery began to adhere to scientific standards with the rise of experimental medicine. The exploration and innovation stage (2011—2023) is the current development phase, during which Chinese Aveolar Surgery has reached its peak, making substantial progress in technology, clinical practices, and basic research, gradually reaching or even surpassing international advanced levels. Looking back at the development history in China, we can find the wisdom and hard work of the older generation of Alveolar Surgery scholars. However, contemporary challenges and issues, such as standardizing technology, promoting clinical practices, and talent cultivation, need to be addressed by present-day Alveolar Surgery professionals as they forge ahead.

Objective:To establish a two-stage surgical procedure of impacted mandibular third molars (IMTM) extractions assisted by coronectomy and microimplant anchorage traction and to investigate the influencing factors of root movement and the effects of different traction angles on the clinical outcomes.Methods:Fifty-three IMTM in contact with inferior alveolar nerve (IAN) that underwent tooth extraction in the Department of Oral and Maxillofacial Surgery Peking University School of Stomatology from January 2022 to June 2023 were included, with coronectomy and microimplant anchorage implantation in the first stage of the surgery, root traction was achieved with orthodontic elastic and microimplant anchorages by about 5.886 N of force, when the IMTM root was detached from IAN, a second surgery was performed to extract the residual root. The basic information of patients and M3M, data on the microimplant anchorage implantation and traction, imaging measurements, and complications were recorded and analyzed.Results:The movement distance of the residual roots was (1.80±0.92) mm, and the duration of traction was (32.9±7.9) d. Multiple linear regression analysis showed that the residual root movement distance was significantly correlated with age, gender, number of roots, traction angle, and depth of the distal bone defect of the second molar ( P<0.05). The smaller the traction angle, the more significant the movement of the residual roots ( P=0.044). In one case, the patient experienced abnormal sensation in the lower lip 16 days after one IMTM (1.9%, 1/53) traction. Conclusions:The two-stage surgical method of combined coronectomy with rapid traction technique to extract the IMTM allows for rapid movement of the residual root and reduces the risk of IAN injury. The efficiency of root movement can be accelerated by appropriately reducing the traction angle during surgery. The traction effect can be predicted based on indicators such as age, gender, number of roots and depth of distal bone defects of second molar.