Objective: To screen dynamic cardiorespiratory fitness indices for effective assessment of aerobic endurance using incremental load exercise tests. Methods: From March to November 2019, 266 volunteers who were able to understand the trial and voluntarily cooperated with the entire testing process were randomly recruited from 5 universities in Beijing. Gas metabolism and cardiac function were monitored in real time using the German Cortex Metalyzer 3B system and the US Cheetah NICOM system, and maximum oxygen uptake was measured by a linear incremental loading scheme. Aerobic endurance and dynamic cardiopulmonary function indices were selected according to the study design, and the relationship between the two indicators was analyzed using correlation and typicality correlation. Results: The absolute maximum oxygen uptake (VO 2max ), relative maximum oxygen uptake, maximum stroke volume (SV max ), and maximum stroke volume index (SVI max ) were significantly higher in males than in females, and the dynamic cardiopulmonary function index K was significantly lower than in females ( t =17.8, 10.1, 8.5, 4.3 , -6.3, P < 0.05 ). Simple correlation revealed that absolute VO 2max and relative VO 2max were negatively correlated with K and b, and absolute VO 2max and relative VO 2max were positively correlated with SV max and SVI max ( P <0.01); Both dynamic cardiopulmonary function indices were significantly correlated with aerobic endurance. Aerobic endurance indexes closely related to dynamic cardiopulmonary function were absolute VO 2max , relative VO 2max ; dynamic cardiopulmonary function indexes closely related to aerobic endurance were K, b, SV max , SVI max . Conclusion Improvement of dynamic cardiorespiratory fitness contributes to the improvement of aerobic endurance, the dynamic cardiorespiratory fitness indices K, b, SV max , and SVI max can be used as important candidates to predict the assessment of aerobic exercise capacity.

BACKGROUND:Heart rate variability biofeedback is a respiratory training method that uses slow and deep breathing at the resonant frequency to induce rhythmic,high-amplitude oscillations in the cardiovascular system,thereby stimulating and exercising the autonomic and baroreflex.However,current studies have not systematically reviewed how heart rate variability biofeedback modulates the autonomic function and produces effects.There is a lack of public understanding of the mechanism of heart rate variability biofeedback,and its application progress and scheme are not fully understood. OBJECTIVE:To review the existing experimental studies on the effects of heart rate variability biofeedback on symptoms in different populations at home and abroad and to introduce the mechanisms and advances in the application of heart rate variability biofeedback to modulate the autonomic nervous system. METHODS:"Heart rate variability biofeedback,resonance breathing,heart rate variability,autonomic nerve,breathing training,chronic diseases,mental illness,biofeedback"were used as Chinese or English keywords to search in CNKI,WanFang Database,PubMed,and Web of Science.A total of 72 core related papers were included according to the inclusion and exclusion criteria. RESULTS AND CONCLUSION:The body's oscillation system and resonance system are essential for the effectiveness of heart rate variability biofeedback.Oscillations reflect the response to external stimuli and self-regulating reflex systems,while resonances involve synchronous oscillations that result in higher amplitude operations.The balance between sympathetic and parasympathetic nerves is crucial for maintaining a stable internal environment.Autonomic nervous system disorders are associated with reduced heart rate variability and are closely linked to the progression of related diseases.Heart rate variability biofeedback utilizes the resonance characteristics of the cardiovascular system,inducing rhythmic high-amplitude oscillations by employing deep slow breathing at the resonance frequency.This method improves the regulatory function of the sympathetic and parasympathetic system reflexes and enhances the balance regulation between the two systems.Two major mechanisms of cardiovascular system resonance are the baroreflex closed-loop pathway and respiratory sinus arrhythmia.These mechanisms,along with the unique delay of baroreflex,result in a 0° phase angle oscillation between heart rate and respiration and a 180° phase angle oscillation between blood pressure and respiration during breathing at the resonant frequency rhythm.Periodically stimulating the human cardiovascular oscillation system through this method is an easy-to-operate and effective training approach.Currently,heart rate variability biofeedback is mainly applied in the fields of mental illness,chronic disease,and sports.However,the intervention mechanism and efficacy are unclear,the intervention content,frequency and duration are varied,and there are limited review studies on the intervention methods tailored to different types of individuals.As a non-drug and non-invasive intervention,heart rate variability biofeedback can significantly increase heart rate variability,regulate the balance between sympathetic and parasympathetic nerves,and improve the stability and adaptability of the autonomic nervous system.In the future,it is suggested to investigate the mechanisms and potential applications of the pathways of the heart rate variability biofeedback that induce cardiovascular resonance.It is also recommended to incorporate long-term follow-ups to assess the sustained value of heart rate variability biofeedback in various fields.This would provide new directions and strategies for the comprehensive treatment of complex diseases.

OBJECTIVES: In light of the rise in the global aging population, this study investigated the potential of the oxidative balance score (OBS) as an indicator of phenotypic age acceleration (PhenoAgeAccel) to better understand and potentially slow down aging. METHODS: Utilizing data from the National Health and Nutrition Examination Survey collected between 2001 and 2010, including 13,142 United States adults (48.7% female and 51.2% male) aged 20 and above, OBS and PhenoAgeAccel were calculated. Weighted generalized linear regression models were employed to explore the associations between OBS and PhenoAgeAccel, including a sex-specific analysis. RESULTS: The OBS demonstrated significant variability across various demographic and health-related factors. There was a clear negative correlation observed between the higher OBS quartiles and PhenoAgeAccel, which presented sex-specific results: the negative association between OBS and PhenoAgeAccel was more pronounced in male than in female. An analysis using restricted cubic splines revealed no significant non-linear relationships. Interaction effects were noted solely in the context of sex and hyperlipidemia. CONCLUSIONS A higher OBS was significantly associated with a slower aging process, as measured by lower PhenoAgeAccel. These findings underscore the importance of OBS as a biomarker in the study of aging and point to sex and hyperlipidemia as variables that may affect this association. Additional research is required to confirm these results and to investigate the biological underpinnings of this relationship.

ObjectiveTo analyze the effectiveness and safety of clinical use of different types of stem cells to provide evidence for governmental supervision of key issues in clinical utilization of stem cells. MethodsSix literature databases in China and abroad were searched for relevant literature published from January 2010 to July 2020， and a systematic review was conducted. ResultsThe study showed 72 studies concerning the effectiveness and safety of different types of stem cells in clinical utilization. Although clinical utilization of stem cells had some therapeutic effects for certain diseases， their long-term effect and safety need to be further evaluated， especially their potential risk of tumorigenicity. ConclusionTo protect the patients’ interest， physicians should fully weigh the benefits against the risks of clinical utilization of stem cells， and relevant governmental departments should strengthen supervision of ethics of clinical research and therapies involving stem cells as well as supervision of stem cell products.

In the paper， national and international ethical requirements and supervision on stem cell research and clinical application were analyzed after literature review. It is suggested that the development of stem cell technology should be timely tracked， prospective ethical research related to stem cells should be enhanced， and that stem cell research and clinical translation should comply with relevant international ethical guidelines and national regulations in China. In addition， it is indicated that the oversight of stem cell products and their clinical use will be continuously improved in our country.