Cardiorespiratory Fitness Index Research Articles

Abstract MP15: Developing and Validating VO 2 Prediction From 6-Minute Walk Test (6MWT) and Association With Cardiovascular Health and Risk Scores: Coronary Artery Risk Development in Young Adults (CARDIA)

Introduction: Cardiorespiratory fitness (CRF) is a valuable diagnostic and prognostic measure. Yet, assessing VO 2 max (indicator of CRF) in population-based studies can be challenging due to requiring sophisticated equipment and trained personnel. Thus, we built and validated a model to estimate VO 2 max from a 6MWT, which is less burdensome for participants (submaximal effort). We tested the hypothesis that our model provides valid estimates of VO 2 max that are associated with cardiovascular health - AHA’s Life’s Simple 7 (LS7) and ASCVD scores. Methods: Data are from 576 CARDIA participants [60% female; 40% Black; mean ± SD age = 61.5 ± 3.6; BMI = 28.6 ± 5.7 kg/m 2 ] who attended the Year 35 follow-up exam (2020-22) and completed VO 2 max and 6MWT tests. The study sample was split randomly into a training (2/3) or test (1/3) set. The prediction equation was developed using stepwise multiple linear regression models in the training set. We evaluated accuracy of the model using student's t-test and Pearson correlation coefficients (r) by examining the difference between the observed and predicted VO 2 max in the test dataset. Linear regression models adjusted for age, and sex were used to examine associations of VO 2 max estimates with cardiovascular health and risk indices. Results: The prediction equation included 6MWT distance, sex, age, BMI, physical activity status, and smoking status (R 2 adj = 0.55, RMSE = 4.84). No significant difference was observed between predicted and measured VO 2 max (26.2 ± 5.4 vs 26.0 ± 7.5 mL/kg/min; p =0.76) and the measures were strongly correlated (r=0.80, p <.001) with Bland-Altman plot is presented (Figure). Predicted VO 2 max explained more variance in LS7 score (R 2 adj = 0.55) compared to measured (R 2 adj = 0.37), while explaining similar variance in ASCVD risk (R 2 adj = 0.40 vs 0.38). Conclusions: This prediction equation provides a convenient and useful estimate of CRF estimate of CRF from 6MWT and may provide utility in clinical practice to screen and monitor CRF when direct measurement is not feasible.

Telehealth Movement-to-Music With Arm-Based Sprint-Intensity Interval Training to Improve Cardiometabolic Health and Cardiorespiratory Fitness in Children With Cerebral Palsy: Protocol for a Pilot Randomized Controlled Trial.

Children with mobility disabilities, including those with cerebral palsy, have limited options and limited time to exercise to manage their cardiometabolic health and cardiorespiratory fitness. Regular cardiovascular exercise during childhood is a critical health behavior for preventing health decline in adulthood. Thus, there is an urgent need for accessible, age-appropriate, convenient exercise modalities in this group. Sprint-intensity interval training (SIT), combined with telehealth procedures, may be ideal for children with disabilities. SIT includes repetitive bouts of maximal exercise effort combined with rest periods, which can be effective in eliciting comparable results to moderate-exercise training with very short training durations. This phase 1 pilot feasibility randomized controlled trial aims to investigate the potential effects of a 12-week SIT program on indicators of cardiorespiratory fitness and cardiometabolic health among children with cerebral palsy. An ancillary aim is to evaluate the feasibility of the program through several process feasibility metrics. This study uses a 2-armed parallel group design. A total of 50 physically inactive children with cerebral palsy (aged 6-17 years) will be randomly allocated into 1 of 2 groups: a 12-week SIT or a waitlist control group that continues habitual activity for 12 weeks. The SIT prescription includes 3 tele-supervised sessions per week with 30 repeated sequences of 4 seconds of maximal arm exercise, with active recovery, warm-up, and cooldown periods (for an approximately 20-minute total session). SIT includes guided videos with child-themed arm routines and music. The exercise sessions will be remotely supervised through a web-based videoconference application and include safety monitoring equipment. Outcomes are measured at pre- and postintervention (weeks 0 and 13, respectively). Health outcome measures include peak oxygen consumption (VO2 peak), measured by a graded exercise test; high-sensitivity C-reactive protein and blood insulin, hemoglobin A1c, triglycerides, and cholesterol using a finger stick dried blood spot test; blood pressure, using a sphygmomanometer; and body composition (total mass, total lean mass, tissue % lean, and tissue % fat) using dual x-ray absorptiometry. Feasibility will be evaluated by the following metrics: adverse events or problems experienced throughout the intervention related to participant safety; perceived enjoyment; and recruitment, enrollment, and attrition rates. Recruitment procedures started in November 2023. All data are anticipated to be collected by February 2025. Full trial results are anticipated to be analyzed and submitted for publication by March 2025. Secondary analyses of data will be subsequently published. This trial tests an accessible and low-cost exercise program that leverages principles of high-intensity exercise to provide a convenient program for children with physical disabilities. Knowledge obtained from this study will inform the development of a larger trial for improving the cardiometabolic health, cardiorespiratory fitness, and well-being of children with physical disabilities. ClinicalTrials.gov NCT05619211; https://clinicaltrials.gov/study/NCT05619211. DERR1-10.2196/56499.

Which indices of cardiorespiratory fitness are more strongly associated with brain health in children with overweight/obesity?

To compare the strength of associations between different indices of cardiorespiratory fitness (CRF) and brain health outcomes in children with overweight/obesity. Participants were 100 children aged 8-11 years. CRF was assessed using treadmill exercise test (peak oxygen uptake [V̇O2peak ], treadmill time, and V̇O2 at ventilatory threshold) and 20-metre shuttle run test (20mSRT, laps, running speed, estimated V̇O2peak using the equations by Léger etal., Mahar etal., and Matsuzaka etal.). Intelligence, executive functions, and academic performance were assessed using validated methods. Total gray matter and hippocampal volumes were assessed using structural MRI. V̇O2peak /body mass (β = 0.18, 95% CI = 0.01-0.35) and treadmill time (β = 0.18-0.21, 95% CI = 0.01-0.39) were positively associated with gray matter volume. 20mSRT laps were positively associated with executive functions (β = 0.255, 95% CI = 0.089-0.421) and academic performance (β = 0.199-0.255, 95% CI = 0.006-0.421), and the running speed was positively associated with executive functions (β = 0.203, 95% CI = 0.039-0.367). Estimated V̇O2peak/Léger etal. was positively associated with intelligence, executive functions, academic performance, and gray matter volume (β = 0.205-0.282, 95% CI = 0.013-0.500). Estimated V̇O2peak/Mahar etal. and V̇O2peak/Matsuzaka etal. (speed) were positively associated with executive functions (β = 0.204-0.256, 95% CI = 0.031-0.436). Although V̇O2peak is considered the gold standard indicator of CRF in children, peak performance (laps or running speed) and estimated V̇O2peak/Léger etal. derived from 20mSRT had stronger and more consistent associations with brain health outcomes than other indices of CRF in children with overweight/obesity.

Relationships between circulating irisin levels, cardiorespiratory fitness, and cardiometabolic risk: a cross-sectional study in Japanese adults.

High cardiorespiratory fitness levels achieved through regular aerobic exercise are associated with reduced cardiometabolic risk. The exercise-induced myokine irisin possibly mediates these associations, but these relationships are unclear. This study aimed to clarify the relationships between circulating irisin levels, cardiorespiratory fitness levels, and cardiometabolic risk factors adjusted for sex and age. This cross-sectional study included 328 Japanese participants aged between 18 and 88 yr. We measured serum irisin levels and peak oxygen uptake (V̇o2peak) as cardiorespiratory fitness indicators, and body fat percentage, blood pressure, fasting blood glucose, hemoglobin A1c (HbA1c), high-density lipoprotein (HDL) cholesterol, and triglycerides as cardiometabolic risk factors. Cardiometabolic risk scores were calculated from the z-scores of the cardiometabolic risk factors. Quintiles based on V̇o2peak or irisin values, categorized by sex, showed a gradual increase in HDL cholesterol and a gradual decrease in other cardiometabolic risk factors with an increase in cardiorespiratory fitness levels or irisin. Serum irisin levels were negatively correlated with body fat percentage, blood pressure, fasting blood glucose, HbA1c, triglyceride levels, and cardiometabolic risk score and positively correlated with HDL cholesterol levels and V̇o2peak in both sexes and young, and middle-aged and older adults. The same relationship was observed in all participants after adjusting for sex and age. These results suggest that circulating irisin levels may be involved in the association between cardiorespiratory fitness and cardiometabolic risk factors, regardless of sex and age.NEW & NOTEWORTHY Circulating irisin levels gradually increased, and cardiometabolic risks gradually decreased with increasing cardiorespiratory fitness levels. The fitness levels required to increase irisin levels were moderate for young adults and lower than moderate for middle-aged and older adults. Moreover, circulating irisin levels are correlated with a reduction in cardiometabolic risk and an increase in cardiorespiratory fitness. These data suggest that circulating irisin levels are involved in the association between cardiorespiratory fitness and cardiometabolic risk.

Declines in Physical Activity and Cardiorespiratory Fitness After Implementing new National School Guidelines

PurposeWe examined whether introduction of national guidelines limiting sports club activities at school was associated with adolescents' exercise and cardiorespiratory fitness. MethodsWe conducted interrupted time-series analysis to quantify the changes in prefecture-level aggregated data on exercise or sports activities and 20-m shuttle run (indicator of cardiorespiratory fitness) among adolescents in Japan before (2013–2017) and after (2018–2022) the introduction of the guidelines using data from the National Survey of Physical Fitness, Athletic Performance and Exercise Habits. ResultsThe introduction of the guidelines was associated with reductions in exercise and sports activities duration (boys, −4.8 [95% CI −5.9, −3.8] min/day; girls, −5.5 [95% CI −6.2, −4.8] min/day) and performance of 20-m shuttle run (boys, −1.2 [95% CI −1.4, −1.0] laps; girls, −2.3 [95% CI −2.5, −2.2] laps). DiscussionAfter introducing guidelines limiting sports club activities at school, levels of exercise or sports and cardiorespiratory fitness declined among adolescents.

Omics-driven investigation of the biology underlying intrinsic submaximal working capacity and its trainability.

Submaximal exercise capacity is an indicator of cardiorespiratory fitness with clinical and public health implications. Submaximal exercise capacity and its response to exercise programs are characterized by heritability levels of about 40%. Using physical working capacity (power output) at a heart rate of 150 beats/min (PWC150) as an indicator of submaximal exercise capacity in subjects of the HERITAGE Family Study, we have undertaken multi-omics and in silico explorations of the underlying biology of PWC150 and its response to 20 wk of endurance training. Our goal was to illuminate the biological processes and identify panels of genes associated with human variability in intrinsic PWC150 (iPWC150) and its trainability (dPWC150). Our bioinformatics approach was based on a combination of genome-wide association, skeletal muscle gene expression, and plasma proteomics and metabolomics experiments. Genes, proteins, and metabolites showing significant associations with iPWC150 or dPWC150 were further queried for the enrichment of biological pathways. We compared genotype-phenotype associations of emerging candidate genes with reported functional consequences of gene knockouts in mouse models. We investigated the associations between DNA variants and multiple muscle and cardiovascular phenotypes measured in HERITAGE subjects. Two panels of prioritized genes of biological relevance to iPWC150 (13 genes) and dPWC150 (6 genes) were identified, supporting the hypothesis that genes and pathways associated with iPWC150 are different from those underlying dPWC150. Finally, the functions of these genes and pathways suggested that human variation in submaximal exercise capacity is mainly driven by skeletal muscle morphology and metabolism and red blood cell oxygen-carrying capacity.NEW & NOTEWORTHY Multi-omics and in silico explorations of the genes and underlying biology of submaximal exercise capacity and its response to 20 wk of endurance training were undertaken. Prioritized genes were identified: 13 genes for variation in submaximal exercise capacity in the sedentary state and 5 genes for the response level to endurance training, with no overlap between them. Genes and pathways associated with submaximal exercise capacity in the sedentary state are different from those underlying trainability.

Effects of high-intensity interval training, moderate-intensity continuous training, and guideline-based physical activity on cardiovascular metabolic markers, cognitive and motor function in elderly sedentary patients with type 2 diabetes (HIIT-DM): a protocol for a randomized controlled trial.

Sedentary behavior is of increasing concern in older patients with type 2 diabetes mellitus (T2DM) due to its potential adverse effects on cardiovascular health, cognitive function, and motor function. While regular exercise has been shown to improve the health of individuals with T2DM, the most effective exercise program for elderly sedentary patients with T2DM remains unclear. Therefore, the objective of this study was to assess the impact of high-intensity interval training (HIIT), moderate-intensity continuous training (MICT), and guideline-based physical activity programs on the cardiovascular health, cognitive function, and motor function of this specific population. This study will be a randomized, assessor-blind, three-arm controlled trial. A total of 330 (1:1:1) elderly sedentary patients diagnosed with T2DM will be randomly assigned the HIIT group (10 × 1-min at 85-95% peak HR, intersperse with 1-min active recovery at 60-70% peak HR), MICT (35 min at 65-75% peak HR), and guideline-based group (guideline group) for 12 weeks training. Participants in the guideline group will receive 1-time advice and weekly remote supervision through smartphones. The primary outcomes will be the change in glycosylated hemoglobin (HbA1c) and brain-derived neurotrophic factor (BDNF) after 12-weeks. Secondary outcomes will includes physical activity levels, anthropometric parameters (weight, waist circumference, hip circumference, and body mass index), physical measurements (fat percentage, muscle percentage, and fitness rate), cardiorespiratory fitness indicators (blood pressure, heart rate, vital capacity, and maximum oxygen), biochemical markers (high-density lipoprotein, low-density lipoprotein, triglycerides, total cholesterol, and HbA1c), inflammation level (C-reactive protein), cognitive function (reaction time and dual-task gait test performance), and motor function (static balance, dynamic balance, single-task gait test performance, and grip strength) after 12 weeks. The objective of this study is to evaluate the effect of 12 weeks of HIIT, MICT, and a guideline-based physical activity program on elderly sedentary patients diagnosed with T2DM. Our hypothesis is that both HIIT and MICT will yield improvements in glucose control, cognitive function, cardiopulmonary function, metabolite levels, motor function, and physical fitness compared to the guideline group. Additionally, we anticipate that HIIT will lead to greater benefits in these areas. The findings from this study will provide valuable insights into the selection of appropriate exercise regimens for elderly sedentary individuals with T2DM. This study has been approved by the Ethics Review Committee of the Reproductive Hospital Affiliated with China Medical University (approval number: 202203). Informed consent will be obtained from all participants or their guardians. Upon completion, the authors will submit their findings to a peer-reviewed journal or academic conference for publication. Chinese Clinical Trial Registry, identifier ChiCTR2200061573.

#3075 EFFECT OF KIDNEY TRANSPLANTATION ON CARDIORESPIRATORY FITNESS ASSESSED WITH CARDIOPULMONARY EXERCISE TESTING: A SYSTEMATIC REVIEW AND META-ANALYSIS

Abstract Background and Aims Patients with kidney failure often present with reduced functional cardiovascular reserve and exercise intolerance. Kidney transplantation is the optimal treatment for patients with end-stage kidney disease as it is associated with longer survival and improved quality of life compared to hemodialysis or peritoneal dialysis. Method This is a systematic review and meta-analysis of studies using cardiopulmonary-exercise-testing (CPET) to examine the cardiorespiratory fitness of patients with kidney failure before and after kidney transplantation. The primary outcome was differences in pre- and post-transplantation values of peak oxygen uptake (VO2peak). Literature search involved PubMed, Web of Science and Scopus databases, manual search of article references and grey literature. Quality assessment was undertaken with Newcastle-Ottawa-Scale. Results From 379 literature records initially retrieved, 6 studies (207 participants) were included in final meta-analysis. A marginal, but not significant, improvement was observed in oxygen consumption during peak exercise compared to pre-transplantation values (standardized mean difference [SMD]: 0.32, 95%CI −0.02; 0.67). Oxygen consumption at anaerobic threshold (VO2AT) was significantly improved after kidney transplantation (weighted MD [WMD]: 2.30 ml/kg/min, 95%CI 0.50; 4.09), whereas no significant changes were observed in maximum heart rate (WMD: 10.45 bpm, 95%CI −3.97; 24.86). In subgroup analysis, consistent results were shown between patients having undergone transplantation preemptively and those after dialysis initiation (p-value for subgroup differences = 0.95). Of note, a trend for improvement in VO2peak was observed when pooling data reported from follow-up assessments undertaken at least 3 months post-transplantation surgery (SMD: 0.17, 95%CI −0.03; 0.38), but not earlier (WMD: −0.03 ml/kg/min, 95%CI −4.28; 4.23). Conclusion Several major indices of cardiorespiratory fitness tend to improve after kidney transplantation compared to pre-transplantation values. This finding may represent another modifiable factor contributing to better survival rates of kidney transplant recipients compared to patients undergoing dialysis.

EFFECT OF KIDNEY TRANSPLANTATION ON INDICES OF CARDIORESPIRATORY FITNESS ASSESSED WITH CARDIOPULMONARY EXERCISE TESTING: A SYSTEMATIC REVIEW AND META-ANALYSIS

Objective: Patients with kidney failure often present with reduced functional cardiovascular reserve and exercise intolerance. Kidney transplantation is the optimal treatment for patients with end-stage kidney disease as it is associated with longer survival and improved quality of life compared to hemodialysis or peritoneal dialysis. Design and method: This is a systematic review and meta-analysis of studies using cardiopulmonary-exercise-testing (CPET) to examine the cardiorespiratory fitness of patients with kidney failure before and after kidney transplantation. The primary outcome was differences in pre- and post-transplantation values of peak oxygen uptake (VO2peak). Literature search involved PubMed, Web of Science and Scopus databases, manual search of article references and grey literature. Quality assessment was undertaken with Newcastle-Ottawa-Scale. Results: From 379 literature records initially retrieved, 6 studies (207 participants) were included in final meta-analysis. A marginal, but not significant, improvement was observed in oxygen consumption during peak exercise compared to pre-transplantation values (standardized mean difference [SMD]: 0.32, 95%CI -0.02; 0.67). Oxygen consumption at anaerobic threshold (VO2AT) was significantly improved after kidney transplantation (weighted MD [WMD]: 2.30 ml/kg/min, 95%CI 0.50; 4.09), whereas no significant changes were observed in maximum heart rate (WMD: 10.45 bpm, 95%CI -3.97; 24.86). In subgroup analysis, consistent results were shown between patients having undergone transplantation preemptively and those after dialysis initiation (p-value for subgroup differences = 0.95). Of note, a trend for improvement in VO2peak was observed when pooling data reported from follow-up assessments undertaken at least 3 months post-transplantation surgery (SMD: 0.17, 95%CI -0.03; 0.38), but not earlier (WMD: -0.03 ml/kg/min, 95%CI -4.28; 4.23). Conclusions: Several major indices of cardiorespiratory fitness tend to improve after kidney transplantation compared to pre-transplantation values. This finding may represent another modifiable factor contributing to better survival rates of kidney transplant recipients compared to patients undergoing dialysis.

STUDY REGARDING THE IMPORTANCE OF MONITORING PHYSIOLOGICAL PARAMETERS IN ELITE FENCING

Introduction. Fencing is a sport that requires psychomotor skills, explosive power, movement speed, reaction speed and physical endurance. Epée and foil fencers have higher aerobic capacity than sabre fencers, whereas épée and foil fencers have similar aerobic capacity. In fact, this can be due to more aerobic nature of épée and foil weapons compared with sabre. Measurement of maximum oxygen uptake (VO2max) is the standard index of cardiorespiratory fitness, but is practical only in a laboratory setting. Over time, numerous VO2 tests have shown that VO2max is a quantifiable and reproducible parameter of the cardiorespiratory system’s ability to meet maximum oxygen requirements. Objective. The aim of this study is to show the importance of monitoring physiological parameters by the Bruce protocol in elite fencing, specifically women’s épée, in order to manage the physical training plan. Methodology. Cardiopulmonary fitness is monitored in dynamic conditions by testing VO2max with the Bruce protocol of the COSMED treadmill Ergometer. This study was carried out over period of 8 weeks in 2021. It should be mentioned that these tests were performed after a specific training plan adapted to the pandemic period. Were included 4 female épée fencers, members of the Romanian National Fencing Team, aged between 22 and 36 years and with outstanding results at national and international levels. Results. From the total of tested physiological parameters were selected the protocol parameters (speed, treadmill incline, time) and metabolic parameters (absolute oxygens consumed (ml/min), maximum oxygens consumed (ml/min/kg), metabolic equivalents, respiratory coefficient, heart rate). These indicators were assessed for anaerobic threshold, respiratory compensation point and at the end of the test. The evolution of these parameters was followed between tests for each subject. Discussions and conclusions. The Bruce Protocol estimates maximal oxygen consumption (VO2 max) as a measure of the athlete's aerobic capacity during sustained effort. In this context, the obtained results highlight an increase of the cardiorespiratory fittness to the women’s épée, an efficient distribution of the oxygen to the tissues and a better adaptation of the cardiac function to the effort. In conclusion, the cardiorespiratory capacity monitoring through the Bruce Protocol can be an important guideline for the physical training to the elite épée fencers.

Fitbit Data to Assess Functional Capacity in Patients Before Elective Surgery: Pilot Prospective Observational Study.

Preoperative assessment is crucial to prevent the risk of complications of surgical operations and is usually focused on functional capacity. The increasing availability of wearable devices (smartwatches, trackers, rings, etc) can provide less intrusive assessment methods, reduce costs, and improve accuracy. The aim of this study was to present and evaluate the possibility of using commercial smartwatch data, such as those retrieved from the Fitbit Inspire 2 device, to assess functional capacity before elective surgery and correlate such data with the current gold standard measure, the 6-Minute Walk Test (6MWT) distance. During the hospital visit, patients were evaluated in terms of functional capacity using the 6MWT. Patients were asked to wear the Fitbit Inspire 2 for 7 days (with flexibility of -2 to +2 days) after the hospital visit, before their surgical operation. Resting heart rate and daily steps data were retrieved directly from the smartwatch. Feature engineering techniques allowed the extraction of heart rate over steps (HROS) and a modified version of Non-Exercise Testing Cardiorespiratory Fitness. All measures were correlated with 6MWT. In total, 31 patients were enrolled in the study (n=22, 71% men; n=9, 29% women; mean age 76.06, SD 4.75 years). Data were collected between June 2021 and May 2022. The parameter that correlated best with the 6MWT was the Non-Exercise Testing Cardiorespiratory Fitness index (r=0.68; P<.001). The average resting heart rate over the whole acquisition period for each participant had r=-0.39 (P=.03), even if some patients did not wear the device at night. The correlation of the 6MWT distance with the HROS evaluated at 1% quantile was significant, with Pearson coefficient of -0.39 (P=.04). Fitbit step count had a fair correlation of 0.59 with 6MWT (P<.001). Our study is a promising starting point for the adoption of wearable technology in the evaluation of functional capacity of patients, which was strongly correlated with the gold standard. The study also identified limitations in the availability of metrics, variability of devices, accuracy and quality of data, and accessibility as crucial areas of focus for future studies.

GLUCOSE INTOLERANCE PREDICTS CARDIORESPIRATORY FITNESS IN A HEALTHY POPULATION

https://youtu.be/oIXKiLYDh6g BACKGROUND Aerobic capacity or maximum oxygen consumption rate (VO2max) is accepted as the single best indicator of cardiorespiratory fitness. VO2max is also an indicator of metabolic health and known as an all-cause mortality predictor. It is well established that glucose intolerance and insulin resistance in patients with diabetes is associated with decline in cardiorespiratory fitness. However, it is not clear if glucose intolerance is associated with poorer cardiorespiratory fitness in a population without diabetes. Therefore, the purpose of this study was to assess if glucose intolerance measured by oral glucose tolerance test (OGTT) is associated with cardiorespiratory fitness in a population without diabetes. METHODS Fifty one (30 males and 21 females) predominantly Mexican-American adults without diabetes (Age 26.1 ± 5.3 years; BMI 26.7 ± 4.2 kg/m2; fasting blood glucose 92.1 ± 10.0 mg/dL) from the border region of El Paso, TX participated in this study. VO2max was assessed using a standardized graded exercise test protocol on a treadmill with Parvomedics metabolic cart. Glucose tolerance was measured by a 3-hour OGTT preformed after a 12-hour overnight fast. Blood glucose measured at fasting and every 30 minutes after the ingestion of 75g of glucose drink during OGTT and glucose area under the curve was determined to access glucose tolerance. Pearson correlation analysis was performed at 0.05 significance level. RESULTS Glucose intolerance measured by glucose area under the curve was negatively correlated with VO2max (r = −0.40, p = 0.006). Additionally, blood glucose level during OGTT test at 120 min (r = −0.43, p = 0.003), 150 min (r = −0.36, p = 0.014), and 180 min (r = −0.32, p = 0.048) were also negatively associated with VO2max. However, fasting blood glucose was not associated with VO2max (r = −0.09, p = 0.56). CONCLUSION Poorer cardiorespiratory fitness is indicated by greater glucose intolerance and a greater surge of glucose level during an OGTT, but not fasting blood glucose in a population without diabetes.

Comparative efficacy of exercise modalities for cardiopulmonary function in hemodialysis patients: A systematic review and network meta-analysis.

To provide reliable evidence to exercise rehabilitation therapists and clinicians, we compared and analyzed the effects of different exercise modalities on cardiopulmonary function in hemodialysis patients using Bayesian network meta-analysis. PubMed, OVID, Web of Science, Cochrane Library, Embase, Scopus, CINAHL, SPORT Discus, SinoMed, CNKI, Wanfang, and VIP were searched from inception to July 20, 2022. We included randomized controlled trials comparing 12 exercise modalities to improve cardiorespiratory fitness in hemodialysis patients. All statistical analysis was performed using STATA and R. A total of 82 randomized controlled trials involving 4146 maintenance hemodialysis patients were included in this study. The pair-wise meta-analysis showed that all exercise modalities had a positive effect on all indicators of cardiorespiratory capacity. The network meta-analysis demonstrated that Blood flow restriction training (BFRT), Cycle exercise (CE), Inspiratory muscle training (IMT), Combined aerobic and resistance training (CT), and Aerobic training (AT) were significantly better than usual care for 6-min walkability; Medium intensity continuous training (MICT), CT, CE, and AT were considerably better than usual care for VO2Peak; body and mind training (MBT) and CT significantly improved SBP compared to usual care; and only MBT was significantly better than usual care for DBP. Both the two-dimensional plot and the radar plot demonstrated that CT had the best combined-effect on each index of cardiorespiratory fitness. Subgroup and sensitivity analyses demonstrated the robustness of the results. The evidence was mainly "low" to "very low" for this network meta-analysis. There is no one exercise that can achieve the best effect on all of the outcomes. The benefits of MBT in decreasing arterial blood pressure are unsurpassed by other exercise methods. The intervention effect of the CT is better and more stable. Electrical muscle stimulation training (MEST) can be employed in individuals who do not wish to exercise actively but may cause an increase in blood pressure. On the basis of the characteristics of different exercise types, guidelines developers, clinicians, and patients may employ them appropriately. https://www.crd.york.ac.uk/PROSPERO/#recordDetails.

Abstract 13030: Non-Exercise Machine Learning Model for Maximal Oxygen Uptake Prediction in National Population Surveys

Introduction: Maximal oxygen uptake (VO 2 max), an indicator of cardiorespiratory fitness (CRF) requires exercise testing and, as a result, is rarely ascertained in large-scale population-based studies. There are many non-exercise algorithms that can estimate VO 2 max, but they are limited by their non-representative study population, lack of predictors, and the insufficient predictive power for the type of model chosen. In this study, we aim to improve the non-exercise algorithms using machine learning (ML) methods and data from U.S. national population surveys. Methods: We used the 1999-2004 data from the National Health and Nutrition Examination Survey (NHANES) because it included exercise testing to measure VO 2 max. Based on the literature review, predictors were identified from demographic, interview, examination, and laboratory data. The study population was split into a training set (80%) and a testing set (20%) for model development and validation. We built the improved model using Light Gradient Boosting Machine (LightGBM) for its outstanding performance and built-in functionality for handling missingness. The model was trained by optimizing Root-Mean Squared Error (RMSE) and using 5-fold cross-validation. Existing non-exercise algorithms for comparison were applied to the testing set. Results: Among the 5,668 participants included, the mean age was 32.5 and 49.9% were women. 40 predictors in total were selected for the final feature set. The fitted LightGBM model achieved an RMSE of 8.43 ml/kg/min (95% CI: 7.64 -9.19) on the testing set, significantly reducing the error by 14% (P &lt;0.05) compared with the best existing non-exercise algorithms that could be cross-validated in NHANES (Table1). Conclusion: In conclusion, the extended non-exercise ML model in this study can provide a more accurate prediction of VO 2 max for NHANES participants, and those with similar data, than the existing non-exercise algorithms.

Effectiveness of cardiopulmonary rehabilitation after COVID-19 in Poland.

Patients with a history of COVID‑19 are characterized by a deteriorated level of cardiorespiratory fitness (CRF). The COVID‑19 rehabilitation program of the National Health Fund (NHF) was developed and financed by the public insurer in Poland to help convalescents return to full health. We aimed to evaluate the effectiveness of cardiopulmonary rehabilitation (CR) after COVID‑19, carried out under the NHF program. The study included 553 convalescents at a mean age of 63.5 years (SD, 10.26; 316 women [57.1%]), hospitalized at the Cardiac Rehabilitation Department of the Ustroń Health Resort, Poland, after a median of 23.10 weeks (interquartile range [IQR], 16.25-29.00) following COVID‑19. The mean duration of CR was 21 days (IQR, 21-28). The effectiveness of CR was assessed based on the improvement in spirometry and clinical parameters, as well as indicators of CRF and exercise tolerance. The mean baseline CRF level, as assessed by the 6‑minute walk test (6MWT), was reduced to 76.32% of the predicted value (SD, 15.87) in men and 85.83% of the predicted value (SD, 15.60) in women, while the mean values of the spirometry parameters were normal. During CR, there was an improvement in the median 6MWT distance by 42.5 m (95% CI, 37.50-45.00; P <0.001), and in the median exercise tolerance assessed on the Borg scale (fatigue, by -1 point; 95% CI, -1.0 to -1.0; P <0.001; dyspnea, by -1.5 points; 95% CI, -1.5 to -1.0; P <0.001). We observed a decrease in the mean resting blood pressure by 8.57 mm Hg (95% CI, -11.30 to -5.84; P <0.001) for systolic and by 3.38 mm Hg (95% CI, -4.53 to -2.23; P <0.001) for diastolic values. The most pronounced improvement was seen in the patients with low CRF level at baseline, who were eligible for lower‑intensity rehabilitation models. The CR effectiveness was not dependent on the severity of COVID‑19 or the time from the disease onset to the commencement of rehabilitation. CR is a safe and effective intervention that can accelerate recovery from COVID‑19, including an increase in exercise capacity and exercise tolerance.

A multi-center, randomized, double-blinded, parallel, placebo-controlled study to assess the efficacy and safety of Shenqisuxin granule in complex coronary artery disease after PCI: Study protocol.

IntroductionThe Shenqisuxin granule (SQSX), a novel Chinese herbal formula, has the effect of preventing in-stent restenosis and improving angiogenesis. We intend to evaluate the efficacy and safety of SQSX to provide a possible therapeutic strategy for complex coronary artery disease (CCAD) after percutaneous coronary intervention (PCI).Methods/designThe study is a multi-center, randomized, double-blinded, parallel, placebo-controlled trial. A total of 120 participants will be randomized 1:1 into the intervention group and the control group. Based on standardized treatment, the intervention group and control group will receive SQSX and placebo for 2 months, respectively. The primary outcomes, metabolic equivalents (METS) and peak oxygen uptake (Peak VO2), and the secondary outcomes, including other indicators of cardiorespiratory fitness (CRF), the European Quality of Life Questionnaire (EQ-5D-5L), the Seattle Angina Scale (SAQ), etc., will be assessed at baseline and 2 months ± 3 days. In addition, the survey scales will also be tested at 1 month ± 3 days. Trimethylamine N-oxide (TMAO), high-sensitivity C-reactive protein (hs-CRP), and gut microbiota features will be assessed at baseline and 2 months ± 3 days to probe possible mechanism. The major adverse cardiac and cerebrovascular events (MACCE) and bleeding events will be monitored until the 12-month follow-up.DiscussionThis study is launched to assess the efficacy and safety of SQSX in CCAD after PCI and probe the possible mechanism.Clinical trial registrationChina Clinical Trial Registry, ChiCTR2200060979, Registered on June 14, 2022.

Decrease of heart rate variability during exercise: An index of cardiorespiratory fitness.

The present study proposes to measure and quantify the heart rate variability (HRV) changes during effort as a function of the heart rate and to test the capacity of the produced indices to predict cardiorespiratory fitness measures. Therefore, the beat-to-beat cardiac time interval series of 18 adolescent athletes (15.2 ± 2.0 years) measured during maximal graded effort test were detrended using a dynamical first-order differential equation model. HRV was then calculated as the standard deviation of the detrended RR intervals (SDRR) within successive windows of one minute. The variation of this measure of HRV during exercise is properly fitted by an exponential decrease of the heart rate: the SDRR is divided by 2 every increase of heart rate of 20 beats/min. The HR increase necessary to divide by 2 the HRV is linearly inversely correlated with the maximum oxygen consumption (r = -0.60, p = 0.006), the maximal aerobic power (r = -0.62, p = 0.006), and, to a lesser extent, to the power at the ventilatory thresholds (r = -0.53, p = 0.02 and r = -0.47, p = 0.05 for the first and second threshold). It indicates that the decrease of the HRV when the heart rate increases is faster among athletes with better fitness. This analysis, based only on cardiac measurements, provides a promising tool for the study of cardiac measurements generated by portable devices.

A Six-Minute Walk Test: Oxygen Uptake and Distance Predicted

Background: Maximum oxygen consumption is an indicator of cardiorespiratory fitness. Aim: The purpose was, first, to relate and compare the V̇O2max as the dependent variable with the estimated distance in the six-minute walk test (SMWT) as the independent variable in university students and, secondly, to relate the distance (dependent) with demographic and anthropometric variables (independents). Methodology: A correlational, descriptive, and quantitative study with a non-experimental design was conducted on 110 university students. In the study, basic anthropometry and vital signs were measured. A direct method of V̇O2max (Bruce test) on a treadmill was applied. Then, the distance covered in the SMWT was evaluated with two equations available in the scientific literature. Differences between men and women were measured in the tests, the correlation between the distances estimated with V̇O2max and anthropometric variables, and repeated ANOVA measurement tests between V̇O2max and estimated distance were analyzed with the SPSS v.22 program (p&lt;0.05). Results: Significant correlations were found between V̇O2max and estimated distances (p&lt;0.05) in the total sample, men and women, and in some cases, the distance correlated with gender, age, weight, height, and BMI (p&lt;0.05). However, there were differences between V̇O2max and distances estimated in the SMWT (p&lt;0.001). Conclusions: The V̇O2max measurement method is different from the distance prediction equations, although they have a significant relationship.&#x0D;

Analysis of the overshoot of the respiratory exchange ratio during recovery from maximal exercise testing in patients with heart failure with reduced ejection fraction

Abstract Funding Acknowledgements Type of funding sources: None. Background Transient increases (overshoot) in respiratory gas analysis parameters have been observed during recovery after maximal cardiopulmonary exercise testing (CPET), but their clinical significance is not clearly understood.(1) Respiratory exchange ratio (RER) at peak exercise (RER peak) is an objective index to evaluate exercise effort.(2) Moreover, overshoot phenomenon of the RER is commonly observed during recovery from CPET.(3) On the other hand, the overshoot of some CPET parameters during recovery has been found reduced in magnitude in patients with heart failure with reduced ejection fraction (HFrEF).(4) Purpose We aimed to examine the clinical significance of RER behaviour after a maximal effort and to understand if this could help in the classification of specific subpopulations of patients. Methods In this cross-sectional study patients with HFrEF who underwent functional evaluation with CPET between 2017 and 2020 were included. A maximal CPET with at least two minute of recorded recovery was performed and always RER achieved at peak of exercise was higher than 1.10. RER behaviour during recovery has been evaluated, assessing its maximal value (RER max), the magnitude of the RER overshoot (RER mag), the time to reach RER max during recovery and the linear slope of increase of the RER from peak exercise to RER max (RER slope). Additionally, subgroup analyses were performed. Results 80 patients with HFrEF were included. Figure 1 shows an example of analyzed RER overshoot parameters. Principal clinical characteristics, CPET parameters and recovery metrics are shown in Table I. Significant correlations between RER recovery parameters and prognostically relevant CPET indices of cardiorespiratory fitness and efficiency were found, especially between RER mag and VO2peak (r=0.333; p=0.03), and RER mag and VE/VCO2slope (r= - 0.494; p&amp;lt;0.01). At multiple linear regression, VE/VCO2slope was the only determinant of RER mag. Patients in a more severe disease state (Ventilatory class III/IV and Weber’s classes C/D) present RER overshoot parameters significantly reduced compared with those in a light/moderate disease state (Ventilatory class I/II and Weber’s classes A/B), (all p=0.01). Conclusions The overshoots phenomena of RER during recovery from maximal exercise were associated with patients’ cardiopulmonary function, and their magnitudes were less prominent in HFrEF patients with a lower cardiorespiratory efficiency. Thus, the evaluation of the overshoot during recovery from CPET might represent an interesting clinical and prognostic tool in patients with HFrEF.

Effect of Interval Training on the Factors Influencing Maximal Oxygen Consumption: A Systematic Review and Meta-Analysis.

The maximal rate of oxygen consumption (VO2max) is an important measure in exercise science as it is an indicator of cardiorespiratory fitness. Individual studies have identified central and peripheral adaptions to interval training that may underlie improvements in VO2max, but there is no compilation of results. We aimed to systematically review the adaptive responses to high-intensity interval training (HIIT) and sprint interval training (SIT) on the central and peripheral factors influencing VO2max in healthy individuals. SPORTDiscus and MEDLINE (up to and including 13 June, 2020) were explored to conduct the literature search. Reviewed studies met the following criteria: (1) were in the English language; (2) prospective in nature; (3) included at least three interval sessions or were at least 1week in duration; (4) contained HIIT or SIT; (5) involved participants between the ages of 18 and 65years; and (6) included at least one of the following central (blood volume, plasma volume, hemoglobin mass, left ventricular mass, maximal stroke volume, maximal cardiac output) or peripheral factors (capillary density, maximal citrate synthase activity, mitochondrial respiration associated with VO2max). Thirty-two studies (369 participants, 49 were female) were included in the quantitative analyses, consisting of both HIIT (n = 18) and SIT (n = 17) interventions. There were only statistically significant changes in hematological measures (plasma volume) following HIIT. There was a significant increase in left ventricular mass following HIIT (7.4%, p < 0.001) and SIT (5.3%, p = 0.007) in inactive individuals, though the change following SIT may be misleading. There was only a significant increase in maximal stroke volume (14.1%, p = 0.015) and maximal cardiac output (12.6%, p = 0.002) following HIIT. In addition to central factors, there was a significant increase in capillary density (13.8%, p < 0.001) following SIT in active individuals. With respect to maximal citrate synthase activity, there were improvements following HIIT (20.8%, p < 0.001) and SIT (15.7%, p < 0.001, I2 = 97%) in active individuals. The results for mitochondrial respiration suggested that there was no statistically significant improvement following HIIT (5.0%, p = 0.585). Improvements in the central and peripheral factors influencing VO2max were dependent on the interval type. Only HIIT led to a statistically significant improvement in cardiac function. Both HIIT and SIT increased maximal citrate synthase activity, while changes in other peripheral measures (capillary density, mitochondrial respiration) only occurred with SIT.