Impact of Cardiorespiratory Fitness on All-Cause and Disease-Specific Mortality: Advances Since 2009

Physical Activity and Cardiorespiratory Fitness as Modulators of Health Outcomes: A Compelling Research-Based Case Presented to the Medical Community

The beneficial health effects and prognostic significance of regular moderate-to-vigorous physical activity (PA), increased cardiorespiratory fitness (CRF), or both are often underappreciated by the medical community and the patients they serve. Individuals with low CRF have higher annual health care costs, higher rates of surgical complications, and are two to three times more likely to die prematurely than their fitter counterparts when matched for risk factor profile or coronary calcium score. Increased levels of habitual PA before hospitalization for acute coronary syndromes are also associated with better short-term cardiovascular outcomes. Accordingly, this review examines these relations and the potential underlying mechanisms of benefit (eg, exercise preconditioning), with specific reference to the incidence of cardiovascular, cancer, and coronavirus diseases, and the prescriptive implications and exercise thresholds for optimizing health outcomes. To assess the evidence supporting or refuting the benefits of PA and CRF, we performed a literature search (PubMed) and critically reviewed the evidence to date. In aggregate, these data are presented in the context of clarifying the impact that regular PA and/or increased CRF have on preventing and treating chronic and infectious diseases, with reference to evidence-based exercise thresholds that the medical community can embrace and promote.

Physical capacity, body composition and immune-inflammatory markers are associated with risk of cardiovascular disease in sedentary people living with HIV

BACKGROUND

People living with HIV (PLHIV) are experiencing a high level of non-HIV-related disease mainly related to cardiovascular system however the factors associated with this scenario are widely discussed and indefinite so far. The purpose was to investigate the association of physical capacities, body composition, and immune-inflammatory markers with the Framingham risk score (FRS) in PLHIV.

METHODS

Volunteers were recruited and data on age, the time of HIV infection diagnosis and the time of HAART use were collected. The volunteers performed upper limb strength (ULS), lower limb strength (LLS) and cardiorespiratory fitness (VO2peak) tests, body composition evaluation, and blood collection to immune-inflammatory marker markers and the FRS was calculated. Partial age- and sex-adjusted correlation was used to verify associations between factors and multiple linear regression analysis was performed to identify an independent association of FRS and the variables.

RESULTS

113 PLHIV met the eligible criteria and were observed a negative correlation between CD4⁺ (r=-0.615), time of HIV infection diagnosis (r=-0.237), time of HAART use (r=-0.239), ULS (r=-0.274), LLS (r=-0.213), and VO<inf>2</inf>peak (r=-0.207) with FRS. There was a positive correlation between fibrinogen and FRS (r=0.363; P<0.001). The TCD4⁺ count cells were significantly associated with FRS (P=0.001).

CONCLUSIONS

Environmental and biological HIV-related factors are inversely associated with FRS while immune-inflammation markers have a positive association.

Leisure-time physical activity, occupational physical activity and the physical activity paradox in healthcare workers: A systematic overview of the literature

BACKGROUND

Physical activity positively influences cardiovascular health. Results from male-dominated physically active occupations suggest that a high level of occupational physical activity may be detrimental to cardiovascular health. This observation is referred to as the physical activity paradox. Whether this phenomenon can also be observed in female-dominated occupations remains unknown.

OBJECTIVE

We aimed to provide an overview of (1) leisure-time and occupational physical activity in healthcare workers. Therefore, we reviewed studies (2) to assess the relationship between the two physical activity domains and analyzed (3) their effects on cardiovascular health outcomes in relation to the paradox.

METHODS

Five databases (CINAHAL, PubMed, Scopus, Sportdiscus, Web of Science) were systematically searched. Both authors independently screened the titles, abstracts, and full texts and assessed the quality of the studies using the National Institutes of Health's quality assessment tool for observational cohort and cross-sectional studies. All studies that assessed leisure-time and occupational physical activity in healthcare workers were included. The two authors independently rated the risk of bias using the ROBINS-E tool. The body of evidence was evaluated using the GRADE approach.

RESULTS

The review included 17 studies that assessed the leisure-time and occupational physical activity of people working in healthcare, determined the relationship between the domains (n = 7) and/or examined their effects on the cardiovascular system (n = 5). Measurements for leisure-time and occupational physical activity varied between studies. Leisure-time physical activity typically ranged between low and high intensity, with a short duration (approx. 0.8-1.5 h). Occupational physical activity was typically performed at light to moderate intensity with a very long duration (approx. 0.5-3 h). Moreover, leisure-time and occupational physical activity were almost negatively related. The few studies investigating effects on cardiovascular parameters revealed a rather unfavorable effect of occupational physical activity, while leisure-time physical activity was beneficial. The study quality was rated as fair and the risk of bias was moderate to high. The body of evidence was low.

CONCLUSIONS

This review confirmed that leisure-time and occupational physical activity of healthcare workers are opposed in their duration and intensity. Moreover, leisure-time and occupational physical activity seem to be negatively related and should be analyzed according to their relation to each other in specific occupations. Furthermore, results support the relationship between the paradox and cardiovascular parameters.

REGISTRATION

Preregistered on PROSPERO (CRD42021254572). Date of registration on PROSPERO: 19 May 2021.

TWEETABLE ABSTRACT

Does occupational physical activity adversely affect the cardiovascular health of healthcare workers in comparison to leisure-time physical activity?

Analysis of Cardiorespiratory Fitness in Early Adulthood and Midlife With All-Cause Mortality and Fatal or Nonfatal Cardiovascular Disease

IMPORTANCE

Optimizing cardiovascular fitness is a prevention strategy against premature death and cardiovascular disease (CVD) events. Since this evidence has largely been established in older populations, the importance of cardiorespiratory fitness during earlier periods of adulthood remains unclear.

OBJECTIVE

To examine the association of early-adulthood cardiorespiratory fitness and percentage of early-adulthood cardiorespiratory fitness retained during midlife with subsequent risk of all-cause mortality and CVD-related morbidity and mortality overall as well as by sex and race.

DESIGN, SETTING, AND PARTICIPANTS

This retrospective population-based cohort study analyzed data from the Coronary Artery Risk Development in Young Adults (CARDIA) study, an ongoing prospective cohort study conducted at field center clinics in Birmingham, Alabama; Chicago, Illinois; Minneapolis, Minnesota; and Oakland, California. Participants in the CARDIA study were aged 18 to 30 years when they completed the baseline graded exercise test protocol in 1985 to 1986 and have since undergone follow-up examinations biannually and every 2 to 5 years. Data were collected through August 31, 2020, and were analyzed in October 2022.

EXPOSURES

Cardiorespiratory fitness was estimated from a symptom-limited, maximal graded exercise test protocol conducted at baseline and at year 7 and year 20 follow-up examinations.

MAIN OUTCOMES AND MEASURES

All-cause mortality and combined fatal and nonfatal CVD events were obtained since year 20 of follow-up examinations through August 31, 2020. Cox proportional hazards regression models were used to estimate hazard ratios (HRs) for each primary exposure with each outcome.

RESULTS

A total of 4808 participants (mean [SD] age at baseline, 24.8 [3.7] years; 2670 females [56%]; 2438 Black individuals [51%]) were included in the sample. During 68 751 person-years of follow-up, there were 302 deaths (6.3%) and 274 CVD events (5.7%) since year 20. Every 1-minute increment in cardiorespiratory fitness at baseline was associated with a lower risk of all-cause mortality in females (HR, 0.73; 95% CI, 0.64-0.82) and males (HR, 0.87; 95% CI, 0.80-0.96). Every 5% increment in cardiorespiratory fitness retained through year 20 was associated with a lower risk of all-cause mortality (HR, 0.89; 95% CI, 0.79-0.99), but no evidence of effect modification by race or sex was found. Every 1-minute increment in cardiorespiratory fitness at baseline was associated with a lower risk of fatal or nonfatal CVD (HR, 0.89; 95% CI, 0.82-0.96), and the estimated HR per 5% increment in cardiorespiratory fitness retained throughout midlife was 0.89 (95% CI, 0.78-1.00), with no evidence for interaction by race or sex.

CONCLUSIONS AND RELEVANCE

This cohort study found that higher early-adulthood cardiorespiratory fitness and greater retention of early-adulthood cardiorespiratory fitness throughout midlife were associated with a lower risk of premature death and CVD events. Additional research is needed to clarify the association of cardiorespiratory fitness timing across the life course with risk of clinical outcomes.

Pre-pregnancy participation and performance in world's largest cross-country ski race as a proxy for physical exercise and fitness, and perinatal outcomes: Prospective registry-based cohort study

OBJECTIVE

Investigate associations between pre-pregnancy participation and performance in a demanding cross-country ski race (proxy for exercise volume and fitness) and perinatal outcomes. Pre-registered protocol: osf.io/aywg2.

DESIGN

Prospective cohort study.

SETTING

Based on entire overlap between the Vasaloppet registry and the population-based Swedish Pregnancy Register.

SAMPLE

All female Vasaloppet participants 1991-2017 with subsequent singleton delivery (skiers), and age- and county-matched non-skiers.

METHODS

We calculated odds ratios (ORs) for non-skiers versus skiers (model 1) and, among skiers, by performance (model 2), in Bayesian logistic regressions adjusted for socio-demographics, lifestyle factors, and comorbidities. We repeated calculations adjusting for early pregnancy body mass index (potential mediator) and explored robustness (selection/exposure settings; multiple comparisons correction).

MAIN OUTCOME MEASURES

Twenty-nine important perinatal outcomes, predefined based on existing expert consensus.

RESULTS

Non-skiers (n = 194 384) versus skiers (n = 15 377) (and slower versus faster performance, not shown) consistently had higher odds of gestational diabetes mellitus (GDM) (OR 1.70, 95% highest density interval: 1.40-2.09), excessive gestational weight gain (GWG) (1.28, 1.22-1.38), psychiatric morbidity (1.60, 1.49-1.72), any caesarean section (CS) (1.34, 1.28-1.40), elective CS (1.39, 1.29-1.49), and large-for-gestational-age babies (>90th percentile, 1.11, 1.04-1.18); lower odds of inadequate GWG (0.83, 0.79-0.88); and no associations with fetal/neonatal complications (e.g. preterm birth [1.09, 0.98-1.20], small for gestational age [SGA] [1.23, 1.05-1.45]). Adjustment for body mass index attenuated associations with excessive (1.20, 1.14-1.30) and inadequate GWG (0.87, 0.83-0.92) and large for gestational age (1.07, 1.00-1.13).

CONCLUSION

Non-skiers compared with skiers, and slower versus faster performance, consistently displayed higher odds of GDM, excessive GWG, psychiatric morbidity, CS and large-for-gestational-age babies; and lower odds of inadequate GWG, after adjustment for socio-demographic and lifestyle factors and comorbidities. There were no associations with fetal/neonatal complications.

Epidemiological, mechanistic, and practical bases for assessment of cardiorespiratory fitness and muscle status in adults in healthcare settings

Given their importance in predicting clinical outcomes, cardiorespiratory fitness (CRF) and muscle status can be considered new vital signs. However, they are not routinely evaluated in healthcare settings. Here, we present a comprehensive review of the epidemiological, mechanistic, and practical bases of the evaluation of CRF and muscle status in adults in primary healthcare settings. We highlight the importance of CRF and muscle status as predictors of morbidity and mortality, focusing on their association with cardiovascular and metabolic outcomes. Notably, adults in the best quartile of CRF and muscle status have as low as one-fourth the risk of developing some of the most common chronic metabolic and cardiovascular diseases than those in the poorest quartile. The physiological mechanisms that underlie these epidemiological associations are addressed. These mechanisms include the fact that both CRF and muscle status reflect an integrative response to the body function. Indeed, muscle plays an active role in the development of many diseases by regulating the body's metabolic rate and releasing myokines, which modulate metabolic and cardiovascular functions. We also go over the most relevant techniques for assessing peak oxygen uptake as a surrogate of CRF and muscle strength, mass, and quality as surrogates of muscle status in adults. Finally, a clinical case of a middle-aged adult is discussed to integrate and summarize the practical aspects of the information presented throughout. Their clinical importance, the ease with which we can assess CRF and muscle status using affordable techniques, and the availability of reference values, justify their routine evaluation in adults across primary healthcare settings.

Baseline and usual cardiorespiratory fitness and the risk of chronic kidney disease: A prospective study and meta-analysis of published observational cohort studies

Chronic kidney disease (CKD) is a global public health burden but is largely preventable. Few studies have reported an association between high levels of cardiorespiratory fitness (CRF) and decreased risk of CKD. However, some relevant aspects of the association, such as the dose-response relationship and the long-term relevance of CRF levels to CKD, have yet to be addressed. We, therefore, aimed to quantify the nature and magnitude of the association between CRF and CKD in a cohort of 2099 men aged 42-61 years with normal kidney function at baseline. CRF was directly measured using a respiratory gas exchange analyzer during cardiopulmonary exercise testing. Hazard ratios (HRs) (95% CIs) were estimated for the incidence of CKD. Correction for within-person variability was made using data from repeat measurements of CRF taken 11 years after baseline. A total of 197 CKD events were recorded during a median follow-up of 25.8 years. The age-adjusted regression dilution ratio for CRF was 0.59 (95% CI: 0.53-0.65). The risk of CKD decreased in a graded fashion with increasing CRF. Comparing extreme tertiles of CRF, the HR (95% CI) for CKD was 0.67 (0.46-0.97) following adjustment for several established and emerging risk factors. The corresponding adjusted HR (95% CI) was 0.51 (0.27-0.96) following correction for within-person variability. In a meta-analysis of five population-based cohort studies (including the current study) comprising 32,447 participants and 4,043 CKD cases, the fully-adjusted risk ratios (95% CIs) for CKD comparing extreme tertiles of baseline and long-term CRF values were 0.58 (0.46-0.73) and 0.40 (0.27-0.59), respectively. Findings from a new prospective study and pooled analysis of previous studies plus the new study indicate that high CRF levels are strongly and independently associated with a reduced risk of CKD and consistent with a linear dose-response relationship. Using single baseline measurements of CRF to investigate the association between CRF and CKD risk could considerably underestimate the true association.

Growing old together: What we know about the influence of diet and exercise on the aging host's gut microbiome

The immune system is critical in defending against infection from pathogenic microorganisms. Individuals with weakened immune systems, such as the elderly, are more susceptible to infections and developing autoimmune and inflammatory diseases. The gut microbiome contains a plethora of bacteria and other microorganisms, which collectively plays a significant role in immune function and homeostasis. Gut microbiota are considered to be highly influential on host health and immune function. Therefore, dysbiosis of the microbiota could be a major contributor to the elevated incidence of multiple age-related pathologies. While there seems to be a general consensus that the composition of gut microbiota changes with age, very little is known about how diet and exercise might influence the aging microbiome. Here, we examine the current state of the literature regarding alterations to the gut microbiome as hosts age, drawing particular attention to the knowledge gaps in addressing how diet and exercise influence the aging microbiome. Further, we will demonstrate the need for more controlled studies to investigate the roles that diet and exercise play driving the composition, diversity, and function of the microbiome in an aging population.

Physical activity, physical fitness and cardiometabolic risk amongst adults with moderate and severe haemophilia

AIM

This study aimed to examine physical activity (PA), physical fitness and cardiometabolic risk amongst people with moderate and severe haemophilia (PwMSH).

METHODS

The following domains were examined: PA (accelerometry); functional aerobic capacity (6-Minute Walk Test); grip strength (dynamometry); balance (One Leg Stand Test); body composition (anthropometry and bioimpedance analysis); blood pressure; arterial stiffness; and cardiometabolic disorders.

RESULTS

A total of 53 PwMSH (44 years) and 33 controls (43 years; p = .679) were recruited. Compared to controls, PwMSH were significantly less active in moderate and vigorous PA parameters (all p < .05), and less physically fit indicated by 6-Minute Walk distance (p < .0005), grip strength (p = .040) and balance (p < .0005). PwMSH had higher rates of abdominal adiposity compared to controls measured by waist circumference indices (all p < .05). Resting blood pressure and arterial stiffness were not significantly different (p = .797 and .818, respectively). With respect to overall PA, World Health Organisation recommended targets for adults were achieved by the majority of both groups (haemophilia: 72.9% vs. controls: 90.0%; p = .069). Importantly, the number of PwMSH who achieved guideline recommended PA via longer, sustained bouts of moderate-vigorous PA was significantly lower compared to controls (18.8% vs. 56.7%; p = .001). Lastly, clinically diagnosed hypertension, insulin resistance and hyperlipidaemia were more prevalent amongst PwMSH compared to controls.

CONCLUSION

Low levels of PA and physical fitness, and significant rates of abdominal adiposity and hypertension may collectively influence the risk and severity of various cardiometabolic and/or musculoskeletal health issues amongst ageing PwMSH. Personalised multi-disciplinary health interventions involving PA, dietary and health psychology input for PwMSH warrant future investigation.

Cardiorespiratory fitness as a vital sign of CVD risk in the COVID-19 era

The severe health consequences of the corona virus disease 2019 (COVID-19) pandemic have been exacerbated by the prevalence of cardiovascular disease (CVD) risk factors, such as physical inactivity, obesity, hypertension, and diabetes. Further, policy decisions during the pandemic augmented unhealthy lifestyle behaviors and health inequalities, likely increasing the global disease burden. Cardiorespiratory fitness (CRF) is a well-established biomarker associated with CVD risk. Emerging data demonstrate that high CRF offers some protection against severe outcomes from COVID-19 infection, highlighting the importance of CRF for population health and the potential for limiting the severity of future pandemics. CRF is best assessed by cardiopulmonary exercise testing (CPET), which will be an important tool for understanding the prolonged pathophysiology of COVID-19, the emergence of long-COVID, and the lasting effects of COVID-19 on CVD risk. Utilization of CRF and CPET within clinical settings should become commonplace because of lessons learned from the COVID-19 pandemic.

External validation of VO2max prediction models based on recreational and elite endurance athletes

In recent years, numerous prognostic models have been developed to predict VO2max. Nevertheless, their accuracy in endurance athletes (EA) stays mostly unvalidated. This study aimed to compare predicted VO2max (pVO2max) with directly measured VO2max by assessing the transferability of the currently available prediction models based on their R2, calibration-in-the-large, and calibration slope. 5,260 healthy adult EA underwent a maximal exertion cardiopulmonary exercise test (CPET) (84.76% male; age 34.6±9.5 yrs.; VO2max 52.97±7.39 mL·min-1·kg-1, BMI 23.59±2.73 kg·m-2). 13 models have been selected to establish pVO2max. Participants were classified into four endurance subgroups (high-, recreational-, low- trained, and "transition") and four age subgroups (18-30, 31-45, 46-60, and ≥61 yrs.). Validation was performed according to TRIPOD guidelines. pVO2max was low-to-moderately associated with direct CPET measurements (p>0.05). Models with the highest accuracy were for males on a cycle ergometer (CE) (Kokkinos R2 = 0.64), females on CE (Kokkinos R2 = 0.65), males on a treadmill (TE) (Wasserman R2 = 0.26), females on TE (Wasserman R2 = 0.30). However, selected models underestimated pVO2max for younger and higher trained EA and overestimated for older and lower trained EA. All equations demonstrated merely moderate accuracy and should only be used as a supplemental method for physicians to estimate CRF in EA. It is necessary to derive new models on EA populations to include routinely in clinical practice and sports diagnostic.

Reference Equation of a New Incremental Step Test to Assess Exercise Capacity in the Portuguese Adult Population

Step tests are important in community- and home-based rehabilitation programs to assess patients' exercise capacity. A new incremental step test was developed for this purpose, but its clinical interpretability is currently limited. This study aimed to establish a reference equation for this new incremental step test (IST) for the Portuguese adult population. A cross-sectional study was conducted on people without disabilities. Sociodemographic (age and sex), anthropometric (weight, height, and body mass index), smoking status, and physical activity (using the brief physical activity assessment tool) data were collected. Participants performed two repetitions of the IST and the best test was used to establish the reference equation with a forward stepwise multiple regression. An analysis comparing the results from the reference equation with the actual values was conducted with the Wilcoxon test. A total of 155 adult volunteers were recruited (60.6% female, 47.8 ± 19.7 years), and the reference equation was as follows: steps in IST = 475.52 - (4.68 × age years) + (30.5 × sex), where male = 1 and female = 0, and r² = 60%. No significant differences were observed between the values performed and those obtained by the equation (p = 0.984). The established equation demonstrated that age and sex were the determinant variables for the variability of the results.

Assessment of Exercise Intensity for Uphill Walking in Healthy Adults Performed Indoors and Outdoors

BACKGROUND

Borg's rating of perceived exertion (BRPE) scale is a simple, but subjective tool to grade physical strain during exercise. As a result, it is widely used for the prescription of exercise intensity, especially for cardiovascular disease prevention. The purpose of this study was to assess and compare relationships between BRPE and physiological measures of exercise intensity during uphill walking indoors and outdoors.

METHODS

134 healthy participants [median age: 56 years (IQR 52-63)] completed a maximal graded walking test indoors on a treadmill using the modified Bruce protocol, and a submaximal 1 km outdoor uphill cardio-trekking test (1 km CTT). Heart rate (HR) and oxygen consumption (V̇O₂) were continuously measured throughout both tests. BRPE was simultaneously assessed at the end of each increment on the treadmill, while the maximal BRPE value was noted at the end of the 1 km CTT.

RESULTS

On the treadmill, BRPE correlated very high with relative HR (%HR_max) (ρ = 0.88, p < 0.001) and V̇O₂ (%V̇O_2max) (ρ = 0.89, p < 0.001). During the 1 km CTT, a small correlation between BRPE and %HR_max (ρ = 0.24, p < 0.05), respectively %V̇O_2max was found (ρ = 0.24, p < 0.05).

CONCLUSIONS

Criterion validity of BRPE during uphill walking depends on the environment and is higher during a treadmill test compared to a natural environment. Adding sensor-based, objective exercise-intensity parameters such as HR holds promise to improve intensity prescription and health safety during uphill walking in a natural environment.

Longitudinal Changes of Cardiorespiratory Fitness Performance in High School: Association with Individual and School-Based Variables

This study aimed to model adolescents' cardiorespiratory fitness performance change trajectories longitudinally across high school years and its relation to school- and individual/student-level factors. We employed hierarchical linear modeling to examine longitudinal cardiorespiratory fitness performance changes, as measured by the progressive aerobic capacity endurance run (PACER), over the years, between sexes, and in association with the school-level variables. Participants were 76,227 adolescents from 80 high schools in the mid-Atlantic region of the United States. School-level academic performance (SAP), the percent of students eligible for free and reduced-price meals (FARM), and physical education student-faculty ratio were obtained with permission from the school districts. The number of laps completed in PACER test improved throughout the first three years of high school, however, proportions of those within the healthy fitness zone (HFZ) decreased overall from 9th to 11th grade. Furthermore, the number of laps completed by adolescents appeared to have plateaued at 11th grade, with a significant decline during the final year of high school. Sex-based discrepancies in performance in meeting HFZ were evident, where girls significantly outperformed boys during 9th and 10th grades, and boys significantly outperformed girls during 12th grade. Additionally, SAP and FARM were positively and negatively, respectively, significantly associated with PACER performance at the school level. The odds ratio of adolescents performing in the HFZ declined significantly over the years, even though the number of PACER laps improved in the first three years. Concerted efforts should be targeted at improving cardiorespiratory fitness in high school due to its positive relationship to academic achievement in schools, and negative association with cardiovascular disease, metabolic syndrome, obesity, and all-cause mortality in adulthood.

What is real change in submaximal cardiorespiratory fitness in older adults? Retrospective analysis of a clinical trial

Objective

To assess the test–retest reliability of submaximal cardiorespiratory fitness in healthy active older adults.

Methods

This was a retrospective analysis of 41 adults enrolled in a clinical trial [mean (sd) aged 59 yrs (7); 29% females; and body mass index 24.5 kg/m² (3.3)]. Cardiorespiratory fitness was assessed using a cycle ergometer 6 weeks apart. The initial workload was 1 W per kilogram of free fat mass (W/kg FFM) and increased by 0.5 W/kg FFM every 3 min until participants could not maintain the speed at ≥ 60 rpm, they reached a rating of perceived exertion of 15–17, and/or obtained a respiratory exchange ratio (RER) of 1.000. Reliability of \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${V}{\text{O}}_{2}$$\end{document}VO2_, heart rate and RER was assessed for each workload, and for \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${V}{\text{O}}_{2}$$\end{document}VO2_, when RER reached 1.00. Reliability was examined as the intraclass correlation coefficient (ICC_(2,1)), Bland–Altman plots, standard error of measurement (SEM and SEM%), and the minimal detectable change (MDC).

Results

Test–retest agreement ranged between (ICC_(2,1) 0.44–0.84) with no discernible systematic differences between assessments. The SEM% for absolute and relative \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${V}{\text{O}}_{2}$$\end{document}VO2 ranged between 13.0 to 20.2%, and 13.8 to 26.3%, respectively_. The MDC₉₀% for absolute and relative \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${V}{\text{O}}_{2}$$\end{document}VO2 ranged between 30.4% to 47.1%, and 32.2% to 61.4%, respectively. The lowest SEMs% and MDCs% for both absolute and relative \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${V}{\text{O}}_{2}$$\end{document}VO2 were observed for workloads at 2.5 W kg/FFM (~ 13% and ~ 31%, respectively).

Conclusions

Although at least modest relative reliability was consistently demonstrated, the smaller measurement error associated with absolute and relative \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${V}{\text{O}}_{2}$$\end{document}VO2 at 2.5 W kg/FFM may indirectly suggest that submaximal cardiorespiratory fitness can be monitored more confidently at higher workloads. Findings provide critical information to determine how much change is considered ‘real change’ in repeated measures of cardiorespiratory fitness using a submaximal graded exercise testing protocol in healthy active older adults.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40798-022-00447-6.

Validity and reproducibility of a method to estimate cardiorespiratory fitness in college adults

Introduction: Cardiorespiratory fitness is a predictor of cardiovascular and all-cause mortality. Its assessment in different groups has clinical and public health usefulness. Objective: To evaluate the validity and reproducibility of a no-exercise method [National Aeronautics and Space Administration (NASA) method] to estimate the maximum oxygen consumption (VO2máx) in college adults. Materials and methods: This study included 94 healthy individuals of both sexes (18-55 years). The gold standard was ergospirometry. The validity and reproducibility were evaluated with the intraclass correlation coefficient (ICC) and the Bland-Altman method. Results: Among the participants, we found a mean age of 30.54 ± 9.33 years and a VO2máx of 41.29 ± 9.54 ml O2.kg-1.min-1; 48.9 % were women. A mean difference of VO2máx between ergospirometry and that estimated by the NASA method of 3.41 ± 5.64 ml O2.kg-1.min-1 was found. The concordance between the two methods was good, with an ICC of 0.858 (CI95% 0.672-0.926). The percentage of error was 29.70 %. The reproducibility of the two estimates by the NASA method was excellent, with an ICC of 0.986 (CI95% 0.927-0.995). Conclusions: The NASA method is valid and reproducible to estimate VO2máx in college adults. In addition, it is safe and easy to apply. Estimating cardiorespiratory fitness is recommended to improve screening in cardiometabolic risk programs and to implement timely interventions.

The Effect of Preterm Birth on Maximal Aerobic Exercise Capacity and Lung Function in Healthy Adults: A Systematic Review and Meta-analysis

BACKGROUND

A negative impact of premature birth on health in adulthood is well established. However, it is not clear whether healthy adults who were born prematurely but have similar physical activity levels compared to adults born at term have a reduced maximal aerobic exercise capacity (maximum oxygen consumption [VO2max]).

OBJECTIVE

We aimed to determine the effect of premature birth on aerobic exercise capacity and lung function in otherwise healthy, physically active individuals.

METHODS

A broad literature search was conducted in the PubMed database. Search terms included 'preterm/premature birth' and 'aerobic exercise capacity'. Maximal oxygen consumption (mL/kg/min) was the main variable required for inclusion, and amongst those investigations forced expiratory volume in 1 s (FEV1, % predicted) was evaluated as a secondary parameter. For the systematic review, 29 eligible articles were identified. Importantly, for the meta-analysis, only studies which reported similar activity levels between healthy controls and the preterm group/s were included, resulting in 11 articles for the VO2max analysis (total n = 688, n = 333 preterm and n = 355 controls) and six articles for the FEV1 analysis (total n = 296, n = 147 preterm and n = 149 controls). Data were analysed using Review Manager ( Review Manager. RevMan version 5.4 software. The Cochrane Collaboration; 2020.).

RESULTS

The systematic review highlighted the broad biological impact of premature birth. While the current literature tends to suggest that there may be a negative impact of premature birth on both VO2max and FEV1, several studies did not control for the potential influence of differing physical activity levels between study groups, thus justifying a focused meta-analysis of selected studies. Our meta-analysis strongly suggests that prematurely born humans who are otherwise healthy do have a reduced VO2max (mean difference: - 4.40 [95% confidence interval - 6.02, - 2.78] mL/kg/min, p < 0.00001, test for overall effect: Z = 5.32) and FEV1 (mean difference - 9.22 [95% confidence interval - 13.54, - 4.89] % predicted, p < 0.0001, test for overall effect: Z = 4.18) independent of physical activity levels.

CONCLUSIONS

Whilst the current literature contains mixed findings on the effects of premature birth on VO2max and FEV1, our focused meta-analysis suggests that even when physical activity levels are similar, there is a clear reduction in VO2max and FEV1 in adults born prematurely. Therefore, future studies should carefully investigate the underlying determinants of the reduced VO2max and FEV1 in humans born preterm, and develop strategies to improve their maximal aerobic capacity and lung function beyond physical activity interventions.

Blood-Based Fingerprint of Cardiorespiratory Fitness and Long-Term Health Outcomes in Young Adulthood

Background Cardiorespiratory fitness is a powerful predictor of health outcomes that is currently underused in primary prevention, especially in young adults. We sought to develop a blood-based biomarker of cardiorespiratory fitness that is easily translatable across populations. Methods and Results Maximal effort cardiopulmonary exercise testing for quantification of cardiorespiratory fitness (by peak oxygen uptake) and profiling of >200 metabolites at rest were performed in the FHS (Framingham Heart Study; 2016-2019). A metabolomic fitness score was derived/validated in the FHS and was associated with long-term outcomes in the younger CARDIA (Coronary Artery Risk Development in Young Adults) study. In the FHS (derivation, N=451; validation, N=914; age 54±8 years, 53% women, body mass index 27.7±5.3 kg/m2), we used LASSO (least absolute shrinkage and selection operator) regression to develop a multimetabolite score to predict peak oxygen uptake (correlation with peak oxygen uptake r=0.77 in derivation, 0.61 in validation; both P<0.0001). In a linear model including clinical risk factors, a ≈1-SD higher metabolomic fitness score had equivalent magnitude of association with peak oxygen uptake as a 9.2-year age increment. In the CARDIA study (N=2300, median follow-up 26.9 years, age 32±4 years, 44% women, 44% Black individuals), a 1-SD higher metabolomic fitness score was associated with a 44% lower risk for mortality (hazard ratio [HR], 0.56 [95% CI, 0.47-0.68]; P<0.0001) and 32% lower risk for cardiovascular disease (HR, 0.68 [95% CI, 0.55-0.84]; P=0.0003) in models adjusted for age, sex, and race, which remained robust with adjustment for clinical risk factors. Conclusions A blood-based biomarker of cardiorespiratory fitness largely independent of traditional risk factors is associated with long-term risk of cardiovascular disease and mortality in young adults.

Comparison of Ratings of Perceived Exertion and Target Heart Rate-Based Exercise Prescription in Cardiac Rehabilitation: A RANDOMIZED CONTROLLED PILOT STUDY

PURPOSE

Although ratings of perceived exertion (RPE) are widely used to guide exercise intensity in cardiac rehabilitation (CR), it is unclear whether target heart rate ranges (THRRs) can be implemented in CR programs that predominantly use RPE and what impact this has on changes in exercise capacity.

METHODS

We conducted a three-group pilot randomized control trial (#NCT03925493) comparing RPE of 3-4 on the 10-point modified Borg scale, 60-80% of heart rate reserve (HRR) with heart rate (HR) monitored by telemetry, or 60-80% of HRR with a personal HR monitor (HRM) for high-fidelity adherence to THRR. Primary outcomes were protocol fidelity and feasibility. Secondary outcomes included exercise HR, RPE, and changes in functional exercise capacity.

RESULTS

Of 48 participants randomized, four patients dropped out, 20 stopped prematurely (COVID-19 pandemic), and 24 completed the protocol. Adherence to THRR was high regardless of HRM, and patients attended a median (IQR) of 33 (23, 36) sessions with no difference between groups. After randomization, HR increased by 1 ± 6, 6 ± 5, and 10 ± 9 bpm ( P = .02); RPE (average score 3.0 ± 0.05) was unchanged, and functional exercise capacity increased by 1.0 ± 1.0, 1.9 ± 1.5, 2.0 ± 1.3 workload METs (effect size between groups, ηp2 = 0.11, P = .20) for the RPE, THRR, and THRR + HRM groups, respectively.

CONCLUSIONS

We successfully implemented THRR in an all-RPE CR program without needing an HRM. Patients randomized to THRR had higher exercise HR but similar RPE ratings. The THRR may be preferable to RPE in CR populations for cardiorespiratory fitness gains, but this needs confirmation in an adequately powered trial.

Physical activity on cardiorespiratory fitness and cardiovascular risk in premenopausal and postmenopausal women: a systematic review of randomized controlled trials

IMPORTANCE

The apparent cardioprotective effects of endogenous estrogens to prevent cardiovascular disease in premenopausal women are reduced with the loss of estrogen post-menopause. Cardiorespiratory fitness and cardiovascular risk factors are closely related to physical activity levels.

OBJECTIVE

This study conducted a critical assessment of studies for health prevention that analyze the effects of physical activity programs on cardiorespiratory fitness and cardiovascular risk factors in women, comparing premenopausal and postmenopausal states, through a systematic review of randomized controlled trials.

EVIDENCE REVIEW

A computerized literature search was performed to include articles up until December 2021 in the following online databases: PubMed, Cochrane, Scopus, SportDiscus, and Web of Science. Regarding physical activity intervention, women of all ages were engaged. The PEDro scale and Oxford's evidence levels were used for the assessment of the risk of bias in the included articles.

FINDINGS

Fourteen scientific articles met the inclusion criteria. Great variability was found in physical activity variables. All the studies found an improvement in at least one variable. The risk of bias was high, with all the articles obtaining a low methodological quality, except two with high methodological quality. Only one article considered the differences in the menopausal state observing the effects of physical activity intervention and highlighting the importance of physical activity in both states.

CONCLUSIONS AND RELEVANCE

To strengthen the evidence for the benefits of physical activity programs in women and to observe the effects depending on their menopausal state, there is an ongoing need for more rigorous randomized controlled trials of appropriate length and dose, with individualized exercise intensity.

Quantile Differences in the Age-Related Decline in Cardiorespiratory Fitness Between Sexes in Adults Without Type 2 Diabetes Mellitus in the United States

Objective

To comprehensively assess the extent to which the decline in cardiorespiratory fitness (CRF) with age differs between sexes.

Participants and Methods

This study used data from the Aerobics Center Longitudinal Study, conducted between September 1974 and August 2006, consisting primarily of White adults from middle-to-upper socioeconomic strata restricted to adults without type 2 diabetes mellitus (33,742 men and 9,415 women). Quantile regression models were used to estimate the differences in age-associated changes in CRF between the sexes, estimated using a maximal treadmill test.

Results

For adults aged up to 45 years, significant differences in slopes relating to age and CRF between men and women were observed for all adjusted percentiles of CRF other than the 90th percentile; women reported significantly greater declines in CRF per year. For those aged 45-60 years and those older than 60 years, no significant differences in age-related declines in CRF were observed between the sexes.

Conclusion

This study found that compared with men, the onset of decline in CRF was found to occur earlier and at lower CRF percentiles in women. This is of particular concern, given that compared with men, women already tend to have lower CRF levels. These findings suggest that maintaining the levels of physical activity sufficient to maintain moderate-to-high levels of fitness is particularly important for women earlier during adulthood.

Reliability of Field-Based Fitness Tests in Adults: A Systematic Review

BACKGROUND

Physical fitness is a powerful predictor of morbidity and mortality, and is therefore a useful indicator for public health monitoring. To assess physical fitness, field-based tests are time-efficient, inexpensive, have minimal equipment requirements, and can be easily administered to a large number of individuals.

OBJECTIVE

The objective of this systematic review was to examine the reliability of existing field-based fitness tests used in adults aged 19-64 years.

METHODS

A systematic search of two electronic databases (MEDLINE and Web of Science) was conducted from inception to 8 June 2021 by two independent researchers. Each study was classified as high, low, or very low quality according to the description of the participants, the time interval between measurements, the description of the results, and the appropriateness of statistics. Three levels of evidence (strong, moderate, and limited) were established according to the number of studies and the consistency of their findings. The study protocol was registered in the International Prospective Register of Systematic Reviews (PROSPERO reference number, CRD42019118480).

RESULTS

Of 17,010 records identified, 129 original studies examining the reliability of field-based fitness tests in adults were considered eligible. The reliability was assessed of tests of cardiorespiratory fitness (33 studies: 30 of high quality), musculoskeletal fitness (92 studies: 78 of high quality), and motor fitness (22 studies, all of high quality). There was strong evidence indicating: (i) the high reliability of the cardiorespiratory fitness tests: 20-m shuttle run, 6-min step, and 6-min walk; (ii) the high reliability of the musculoskeletal fitness tests: handgrip strength, back-leg strength, Sorensen, trunk flexion sustained, 5-reps sit-to-stand, sit-and-reach and toe-touch, and moderate reliability bilateral side bridge and prone bridge tests; and (iii) the moderate reliability and low reliability, respectively, of the motor fitness tests T-test and single-leg stand. We found moderate evidence indicating the moderate or high reliability of the following tests: Chester, sit-up, partial curl-up, flexion-rotation trunk, timed stair ascent, pull-up, bent-arm hang, standing broad jump, hop sequence, trunk lift, timed-up-and-go, and hexagon agility. Evidence for the reliability of balance and gait speed tests was inconclusive. Other field-based fitness tests demonstrated limited evidence, mainly due to there being only few studies.

CONCLUSIONS

This review provides an evidence-based proposal of the more reliable field-based fitness tests for adults aged 19-64 years. Our findings identified a need for more high-quality studies designed to assess the reliability of field-based tests of lower and upper body explosive and endurance muscular strength, and motor fitness (i.e., balance and gait speed tests) in adults.

A Telemedicine Alternative to the 6-Minute Walk Test Using Personal Activity Trackers in Liver Transplant Candidates

The COVID-19 pandemic has limited liver transplant (LT) candidates access to clinics. Telehealth methods to assess frailty are needed. We developed a method to estimate the step length of LT candidates, which would permit remotely obtaining the 6-min walk test (6MWT) distance with a personal activity tracker (PAT).

Methods

6MWT was performed while candidates wore a PAT. On first 21 subjects (stride cohort), the step length was measured and compared with calculated one (6MWT-distance/6MWT steps). On a second cohort (PAT-6MWT; n = 116), we collected the 6MWT step count and used multivariable models to generate formulas estimating step length. We multiplied the estimated step length times 6MWT steps to estimate the distance and compared it to the measured distance. The liver frailty index (LFI) and 6MWT were used as frailty metrics.

Results

Measured/calculated step length were highly correlated (ρ = 0.85; P < 0.001) in the stride cohort. In the PAT-6MWT cohort, LFI was the strongest variable associated with step length, along with height, albumin, and large-volume paracentesis (R ² = 0.58). On a second model without LFI, age, height, albumin, hemoglobin, and large-volume paracentesis were strongly associated with step length (R ² = 0.45). There was a robust correlation between observed 6MWT and PAT-6MWT utilizing step length equations with (ρ = 0.80; P < 0.001) or without LFI (ρ = 0.75; P < 0.001). Frailty by 6MWT <250 m did not change significantly using the observed (16%) or the with/without LFI-estimated (14%/12%) methods.

Conclusions

We created a method to obtain 6MWT distance remotely with the use of a PAT. This novel approach opens the possibility of performing telemedicine PAT-6MWT to monitor LT candidates' frailty status.

The effects of regular sauna bathing in conjunction with exercise on cardiovascular function: A multi-arm randomized controlled trial

Regular exercise and sauna bathing have each been shown to improve cardiovascular function in clinical populations. However, experimental data on the cardiovascular adaptations to regular exercise in conjunction with sauna bathing in the general population is lacking. Therefore, we compared the effects of exercise and sauna bathing, to regular exercise using a multi-arm randomized controlled trial. Participants (n = 47) aged 49 ± 9 years with low physical activity levels, and at least one traditional CVD risk factor were randomly assigned (1:1:1) to guideline-based regular exercise and 15-minute post-exercise sauna (EXS), guideline-based regular exercise (EXE), or control (CON), for eight weeks. The primary outcomes were blood pressure (BP) and cardiorespiratory fitness (CRF)_. Secondary outcomes included fat mass, total cholesterol levels, and arterial stiffness. EXE had a greater change in CRF (+6.2 ml/kg/min; 95% CI, +4.2. to +8.3 ml/kg/min) and fat mass, but no differences in BP when compared to CON. EXS displayed greater change in CRF (+2.7 ml/kg/min; 95% CI, +0.2. to +5.3 ml/kg/min), lower systolic BP (-8.0 mmHg; 95% CI, -14.6 to -1.4 mmHg) and lower total cholesterol levels compared to EXE. Regular exercise improved CRF and body composition in sedentary adults with CVD risk factors. However, when combined with exercise, sauna bathing demonstrated a substantially supplementary effect on CRF, systolic BP, and total cholesterol levels. Sauna bathing is a valuable lifestyle tool that complements exercise for improving CRF, and decreasing systolic BP. Future research should focus on the duration, and frequency of exposure to ascertain the dose-response relationship.

Association between cardiorespiratory fitness and risk of all-cause and cause-specific mortality

OBJECTIVE

The association of cardiorespiratory fitness (CRF) with all-cause and cause-specific mortality remains unclear in Chinese population. This study aimed to evaluate the risk of all-cause, cardiovascular disease (CVD), cancer and other-cause mortality in Chinese adults using estimated CRF (eCRF).

PATIENTS AND METHODS

We analysed data for 15,566 participants aged ≥20 years recruited in The Rural Chinese Cohort Study during 2007 to 2008 and followed for mortality during 2013 to 2014. eCRF was calculated with sex-specific longitudinal non-exercise algorithms. Cox proportional-hazards models were used to calculate hazard ratios (HRs) and 95% confidence intervals (CIs) for all-cause and cause-specific mortality risk according to baseline eCRF.

RESULTS

During a median of 6.01 years of follow-up, 859 deaths occurred, including 359 from CVD, 221 from cancer, and 279 from other causes. Each 1 metabolic equivalent increment in eCRF was associated with decreased risk of all-cause mortality (men: HR 0.70, 95% CI [0.66-0.74]; women: 0.59, [0.54-0.64]); CVD mortality (men: 0.70 [0.64-0.77]; women: 0.55, [0.48-0.62]); and other-cause mortality (men: 0.68 [0.62-0.75]; women: 0.57, [0.49-0.66]). The area under receiver operating characteristic curve was significantly higher for eCRF than its modifiable components (waist circumference, body mass index and resting heart rate) in predicting all-cause and cause-specific mortality incidence (all p < .001).

CONCLUSION

eCRF was inversely associated with all-cause, CVD and other-cause mortality.

Cardiorespiratory Fitness, BMI, Mortality, and Cardiovascular Disease in Adults with Overweight/Obesity and Type 2 Diabetes

INTRODUCTION

We estimated the effects of cardiorespiratory fitness (CRF) and body mass index (BMI) at baseline on mortality and cardiovascular disease events in people with type 2 diabetes who participated in the Look AHEAD randomized clinical trial.

METHODS

Look AHEAD compared effects of an intensive lifestyle intervention with diabetes support and education on cardiovascular disease events in 5145 adults age 45-76 yr with overweight/obesity and type 2 diabetes. In 4773 participants, we performed a secondary analysis of the association of baseline CRF during maximal treadmill test (expressed as metabolic equivalents (METs)) on mortality and cardiovascular disease events during a mean follow-up of 9.2 yr.

RESULTS

The mean (SD) CRF was 7.2 (2.0) METs. Adjusted for age, sex, race/ethnicity, BMI, intervention group, and β-blocker use, all-cause mortality rate was 30% lower per SD greater METs (hazard ratio (HR) = 0.70 (95% confidence interval, 0.60 to 0.81); rate difference (RD), -2.71 deaths/1000 person-years (95% confidence interval, -3.79 to -1.63)). Similarly, an SD greater METs predicted lower cardiovascular disease mortality (HR, 0.45; RD, -1.65 cases/1000 person-years) and a composite cardiovascular outcome (HR, 0.72; RD, -6.38). Effects of METs were homogeneous on the HR scale for most baseline variables and outcomes but heterogeneous for many on the RD scale, with greater RD in subgroups at greater risk of the outcomes. For example, all-cause mortality was lower by 7.6 deaths/1000 person-years per SD greater METs in those with a history of cardiovascular disease at baseline but lower by only 1.6 in those without such history. BMI adjusted for CRF had little or no effect on these outcomes.

CONCLUSIONS

Greater CRF is associated with reduced risks of mortality and cardiovascular disease events.

Objectively Assessed Cardiorespiratory Fitness and All-Cause Mortality Risk: An Updated Meta-analysis of 37 Cohort Studies Involving 2,258,029 Participants

OBJECTIVE

To detail the magnitude and specificity of the association between cardiorespiratory fitness (CRF) and all-cause mortality risk.

METHODS

Cohort studies with at least 1 year of follow-up were sought from inception until December 2021 in MEDLINE, Embase, Web of Science, and a manual search of relevant articles. Relative risks (RRs) with 95% CIs were pooled using random-effects models. Quality of the evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation tool.

RESULTS

A total of 37 unique studies comprising of 2,258,029 participants with 108,613 all-cause mortality events were eligible. The pooled multivariable-adjusted RR for all-cause mortality comparing the top vs bottom tertiles of CRF levels was 0.55 (95% CI, 0.50 to 0.61). When CRF was expressed in metabolic equivalent task (MET) units, the corresponding pooled RR was 0.56 (95% CI, 0.50 to 0.62). For every 1-MET increase in CRF, the RR for all-cause mortality was 0.89 (95% CI, 0.86 to 0.92). Strength of the association did not differ by publication year, age, sex, follow-up duration, CRF assessment method, or risk of bias.

CONCLUSION

Aggregate analysis of observational cohort studies confirms a strong inverse and independent association between CRF and all-cause mortality risk. The results suggest that guideline bodies should consider the inclusion of CRF in standard risk panels for mortality risk assessment.

Non-invasive MR imaging techniques for measuring femoral arterial flow in a pediatric and adolescent cohort

Magnetic Resonance Imaging (MRI) is well‐suited for imaging peripheral blood flow due to its non‐invasive nature and excellent spatial resolution. Although MRI is routinely used in adults to assess physiological changes in chronic diseases, there are currently no MRI‐based data quantifying arterial flow in pediatric or adolescent populations during exercise. Therefore the current research sought to document femoral arterial blood flow at rest and following exercise in a pediatric‐adolescent population using phase contrast MRI, and to present test‐retest reliability data for this method. Ten healthy children and adolescents (4 male; mean age 14.8 ± 2.4 years) completed bloodwork and resting and exercise MRI. Baseline images consisted of PC‐MRI of the femoral artery at rest and following a 5 × 30 s of in‐magnet exercise. To evaluate test‐retest reliability, five participants returned for repeat testing. All participants successfully completed exercise testing in the MRI. Baseline flow demonstrated excellent reliability (ICC = 0.93, p = 0.006), and peak exercise and delta rest‐peak flow demonstrated good reliability (peak exercise ICC = 0.89, p = 0.002, delta rest‐peak ICC = 0.87, p = 0.003) between‐visits. All three flow measurements demonstrated excellent reliability when assessed with coefficients of variance (CV’s) (rest: CV = 6.2%; peak exercise: CV = 7.3%; delta rest‐peak: CV = 7.1%). The mean bias was small for femoral arterial flow. There was no significant mean bias between femoral artery flow visits 1 and 2 at peak exercise. There were no correlations between age or height and any of the flow measurements. There were no significant differences between male and female participants for any of the flow measurements. The current study determined that peripheral arterial blood flow in children and adolescents can be evaluated using non‐invasive phase contrast MRI. The MRI‐based techniques that were used in the current study for measuring arterial flow in pediatric and adolescent patients demonstrated acceptable test‐retest reliability both at rest and immediately post‐exercise.

Current state of unhealthy living characteristics in White, African American and Latinx populations

The United States (US) is similar to most industrialized countries in that it falls short on many of the basic metrics related to cardiovascular and overall health. These metrics include nutritional patterns, levels of physical activity (PA), cardiorespiratory fitness (CRF), and prevalence of overweight and obesity. These issues are even more apparent in underserved communities, among whom unhealthy living characteristics cluster and contribute to a disproportionate chronic disease burden. The reasons for these inequities are complex and include social and economic factors as well as reduced access to health care. CRF has been demonstrated to be a critically important risk factor that tends to be lower in disadvantaged groups. In this article we discuss the current state of health & lifestyle characteristics in the US, the impact of social inequality on health, and the particular role that CRF and PA patterns play in the current state of unhealthy living characteristics as they relate to underserved populations.

Evaluation of Maintained PhysicAl CaPacity 1-yr After Coronary Patient Cardiac Rehabilitation (EMAP): A FRENCH MULTICENTER STUDY

PURPOSE

Data are scarce concerning the sustainable effects of cardiac rehabilitation (CR), on cardiorespiratory fitness (CRF) of patients with coronary artery disease (CAD). This study, carried out using data from a French multicenter study, aimed to clarify the evolution of the CRF of patients with CAD 1 yr after the end of a CR stay.

METHODS

Patients were included after an acute coronary syndrome (77%) and/or coronary revascularization, occurring <3 mo beforehand. All underwent a CR program with CRF evaluation by exercise testing (ET) on a cycle ergometer at the beginning of CR (ET1), at its end (ET2), and 1 yr later (ET3)-all ETs were performed with medication.

RESULTS

Two hundred fifty-nine patients were included (age 60 ± 10 yr, 89% male) in 16 French CR centers. Left ventricular ejection fraction was 55.3 ± 9%. Revascularization was complete (82%). Maximal workloads were 110 ± 37 (ET1), 139 ± 43 (ET2), and 144 ± 46 W (ET3) (P< .001). The estimated metabolic equivalents of the task (METs) were respectively 5.3 ± 1.4, 6.4 ± 1.6 (P< .001), and 6.6 ± 1.7 (P< .002). One year later, 163 patients (63%) improved or maintained their CRF (ET3 ≥ ET2), 73 (28%) decreased (ET1 < ET3 < ET2), and 23 (9%) lost the benefit of CR (ET3 ≤ ET1).

CONCLUSION

Among completers who agreed to enroll in this study, most patients with CAD seem to maintain their CRF 1 yr after CR.

Non-exercise estimated cardiorespiratory fitness and mortality from all-causes, cardiovascular disease, and cancer in the NIH-AARP diet and health study

AIMS

Impractical methods and relatively small cohort have limited the applications of non-exercise estimated cardiorespiratory fitness (NEE-CRF). This study aimed to assess the association between a pragmatic NEE-CRF method and mortality outcomes in a large prospective cohort.

METHODS AND RESULTS

A total of 330 769 participants [men (n = 186 469) and women (n = 144 300)] aged 50-71 years from the NIH-AARP Diet and Health Study were assessed at baseline (1995-96) and prospectively followed until 31 December 2015 (14.9 ± 2.1 years). Non-exercise estimated cardiorespiratory fitness was estimated using pragmatic and previously validated equation, and Cox hazard analysis for mortality was conducted. Non-exercise estimated cardiorespiratory fitness was 9.9 ± 1.5 metabolic equivalents (METs) in men and 7.2 ± 1.6 METs in women. In total, 34 317 men and 20 295 women died during the follow-up. Higher NEE-CRF was associated with lower mortality risk from all-causes, cardiovascular disease, and cancer. Compared to the lowest quartile of NEE-CRF, the hazard ratios and 95% confidence interval for all-cause mortality in the second, third, and fourth quartiles were: 0.82 (0.79-0.84), 0.74 (0.72-0.77), and 0.70 (0.67-0.73) for men, and 0.84 (0.81-0.88), 0.78 (0.75-0.82), and 0.72 (0.68-0.77) for women (P trend <0.001 for all). For each 1-MET increase in NEE-CRF, risks for mortality due to cardiovascular disease and cancer were 0.85 (0.82-0.88) and 0.89 (0.87-0.91) in men, and 0.84 (0.81-0.88) and 0.89 (0.87-0.91) in women, respectively (P < 0.001 for all).

CONCLUSION

Higher NEE-CRF is independently associated with lower mortality risk in a large prospective cohort of men and women. These results support the utility of the applied NEE-CRF method for risk stratification, prevention, and rehabilitation programs and application in large epidemiological studies.

From the Lab to Real Life: Monitoring Cardiorespiratory Fitness during the COVID-19 Pandemic through Wearable Devices. An Exploratory Longitudinal Study on Healthy Participants

COVID-19 containment measures hampered population cardiorespiratory fitness (which can be quantified as peak oxygen consumption (V.O_2peak)) and the possibility to assess it using laboratory-based techniques. Although it is useful to ascertain the V.O_2peak recovery after lockdowns, the community and most scientific institutions were unable to evaluate it. Wearable devices may provide the opportunity to estimate cardiorespiratory fitness outside of the laboratory, without breaking self-isolation; herein, we explore the feasibility of this approach. Fifteen healthy participants were tested every 2 weeks for 10 weeks during a reduction of containment measures after a strict lockdown. Physical activity levels were measured using the International Physical Activity Questionnaire-Short Form (IPAQ-SF). V.O_2peak was estimated through a previously validated test based on the speed of a 60 m sprint run, the baseline-to-peak heart rate (HR) variation, and the velocity of HR decay after the sprint, and measured through a wearable HR monitor. Participants increased physical activity from the end of lockdown (1833 [917–2594] MET-min/week; median [1st quartile–3rd quartile]) until the end of follow-up (2730 [1325–3380] MET-min/week). The estimated V.O_2peak increased by 0.24 ± 0.19 mL/(min*kg*week) (regression coefficient ± standard error). Based on previous knowledge on the impact of inactivity on V.O_2peak, our study indicates that a 10-week period of reducing the stringency of containment measures may not be sufficient to counteract the detrimental effects of the preceding lockdown.

Cardiac Rehabilitation and Resting Blood Pressure: MONTANA OUTCOMES PROJECT CARDIAC REHABILITATION REGISTRY FINDINGS

PURPOSE

Exercise-based cardiac rehabilitation (CR) is essential for treating cardiovascular disease, and modifying risk factor modification, including hypertension. Because the causes of hypertension and benefits of CR are faceted, we examined the influence of phase II CR on resting blood pressure (BP).

METHODS

Outcomes straddle the release of the updated BP guidelines, and study emphases included CR session number, sex, race/ethnicity, insurance provider, and referring diagnosis.

RESULTS

Patient files of 31 885 individuals uploaded to the Montana Outcomes Project registry indicated that lowered systolic and diastolic BP were further improved after the release of the revised BP guidelines. The CR session number was proportional to improvements in diastolic BP. Blood pressure improved independent of sex, although female patients exhibited lower diastolic BP before and after CR. Race/ethnicity analyses indicated that Asian and White patients experienced drops in systolic and diastolic BP, while diastolic BP was improved in Hispanic patients. Neither American Indian nor Black patients exhibited statistically altered BP. Medicare, Veterans Administration, and privately insured patients had lowered systolic and diastolic BP, while Medicaid patients had lower diastolic BP, and the uninsured had lower systolic BP. Blood pressure outcomes were generally improved independent of the primary referring diagnosis, while those with peripheral artery disease showed no improvements.

CONCLUSIONS

Findings demonstrate that phase II CR is highly effective in the control of BP, although improvements are not equally distributed to all individuals according to differences in sex, race/ethnicity, and access to insurance-funded health care.

Can exercise training teach us how to treat Alzheimer's disease?

Alzheimer's disease (AD) is the most common cause of dementia and there is currently no cure. Novel approaches to treat AD and curb the rapidly increasing worldwide prevalence and costs of dementia are needed. Physical inactivity is a significant modifiable risk factor for AD, estimated to contribute to 12.7% of AD cases worldwide. Exercise interventions in humans and animals have shown beneficial effects of exercise on brain plasticity and cognitive functions. In animal studies, exercise also improved AD pathology. The mechanisms underlying these effects of exercise seem to be associated mainly with exercise performance or cardiorespiratory fitness. In addition, exercise-induced molecules of peripheral origin seem to play an important role. Since exercise affects the whole body, there likely is no single therapeutic target that could mimic all the benefits of exercise. However, systemic strategies may be a viable means to convey broad therapeutic effects in AD patients. Here, we review the potential of physical activity and exercise training in AD prevention and treatment, shining light on recently discovered underlying mechanisms and concluding with a view on future development of exercise-free treatment strategies for AD.

Lifestyle changes in patients with non-alcoholic fatty liver disease: A systematic review and meta-analysis

Background

Non-alcoholic fatty liver disease is a liver condition that is increasing worldwide and expected to become the number one cause of cirrhosis and hepatocellular carcinoma in the next 5 years. Currently there are no successful or approved pharmacological treatments. Weight loss is the first-line therapy as a 7 to 10% reduction improves steatosis, inflammation, hepatocyte ballooning, and fibrosis. To achieve this, lifestyle interventions including daily exercise and diet must be encouraged. We aimed to assess the effects of diet, exercise, or a combination of both compared to conventional treatment in patients with non-alcoholic fatty liver disease.

Methods and finding

A literature search was performed in CENTRAL, EMBASE, and PubMed. Randomized controlled trials comparing lifestyle changes with conventional treatment were included, without date restriction. Two authors searched studies according to eligibility criteria, extracted data, and assessed study quality. Subgroup analysis was made by type of intervention, duration of intervention and supervision. We calculated mean differences between the intervention and the control group with their corresponding 95% confidence intervals. Quality of the evidence was assessed using the Cochrane Risk of bias tool. This study is registered in PROSPERO, number CRD42020184241, and checked with the PRISMA checklist. 30 RCTs met the inclusion criteria. Compared to conventional treatment, combined exercise with diet seems to elicit greater reductions in ALT (MD: -13.27 CI 95% -21.39, -5.16), AST (MD: -7.02 CI 95% -11.26, -2.78) and HOMA-IR (MD: -2.07 CI 95% -2.61, -1.46) than diet (ALT MD: -4.48 CI 95% -1.01, -0.21; HOMA-IR MD: -0.61 CI 95% -1.01, -0.21) and exercise (ALT and AST non-significant; HOMA-IR MD = -0.46 CI 95% -0.8, -0.12) alone. Additionally, exercise improved quality of life, cardiorespiratory fitness, and weight (MD: -2.64 CI 95% -5.18, -0.09).

Conclusion

Lifestyle changes are effective in the treatment of NAFLD. Diet and exercise combined are superior to these interventions alone in improving liver enzymes and HOMA-IR.

Percentage of Age-Predicted Cardiorespiratory Fitness and Risk of Incident Hypertension: A PROSPECTIVE COHORT STUDY

PURPOSE

There are inverse and independent associations between cardiorespiratory fitness (CRF) and several adverse cardiometabolic outcomes including hypertension (HTN). The prospective relationship between percentage of age-predicted CRF and risk of HTN has not been previously investigated. We aimed to assess the association of percentage of age-predicted CRF with incident HTN in a long-term prospective cohort study.

METHODS

Cardiorespiratory fitness, as measured by peak oxygen uptake, was assessed using the gold standard respiratory gas exchange analyzer in 1602 men who underwent cardiopulmonary exercise testing. The age-predicted CRF estimated from a regression equation for age was converted to percentage of age-predicted CRF ([achieved CRF/age-predicted CRF] × 100). The HR with 95% CI were estimated for HTN.

RESULTS

During a median follow-up of 26.8 yr, 308 HTN cases were recorded. There was a linear relationship between age-predicted CRF and incident HTN (P value for nonlinearity = .68). A 1-SD increase in percentage of age-predicted CRF was associated with a decreased risk of HTN in analysis adjusted for established risk factors (HR = 0.79: 95% CI, 0.69-0.90), which remained consistent on further adjustment for several other potential confounders including alcohol consumption, physical activity, socioeconomic status, and inflammation (HR = 0.83: 95% CI, 0.72-0.95). The corresponding adjusted HRs were 0.55 (95% CI, 0.38-0.80) and 0.63 (95% CI, 0.43-0.91), respectively, when comparing extreme quartiles of percentage of age-predicted CRF levels.

CONCLUSIONS

Percentage of age-predicted CRF is linearly, inversely, and independently associated with risk of incident HTN, and it is comparable to absolute CRF as a risk indicator for HTN in a general population of middle-aged men.

The Aging Athlete: Paradigm of Healthy Aging

The Exercise Boom of the 1970's resulted in the adoption of habitual exercise in a significant portion of the population. Many of these individuals are defying the cultural norms by remaining physically active and competing at a high level in their later years. The juxtaposition between masters athletes and non-exercisers demonstrate the importance of remaining physically active throughout the lifespan on physiological systems related to healthspan (years of healthy living). This includes ~50% improved maximal aerobic capacity (VO₂max) and enhanced skeletal muscle health (size, function, as well as metabolic and communicative properties) compared to non-exercisers at a similar age. By taking a reductionist approach to VO₂max and skeletal muscle health, we can gain insight into how aging and habitual exercise affects the aging process. Collectively, this review provides a physiological basis for the elite performances seen in masters athletes, as well as the health implications of lifelong exercise with a focus on VO₂max, skeletal muscle metabolic fitness, whole muscle size and function, single muscle fiber physiology, and communicative properties of skeletal muscle. This review has significant public health implications due to the potent health benefits of habitual exercise across the lifespan.

Single-leg exercise training augments in vivo skeletal muscle oxidative flux and vascular content and function in adults with type 2 diabetes

KEY POINTS

People with type 2 diabetes (T2D) have impaired skeletal muscle oxidative flux due to limited oxygen delivery. In the current study, this impairment in oxidative flux in people with T2D was abrogated with a single-leg exercise training protocol. Additionally, single-leg exercise training increased skeletal muscle CD31 content, calf blood flow and state 4 mitochondrial respiration in all participants.

ABSTRACT

Cardiorespiratory fitness is impaired in type 2 diabetes (T2D), conferring significant cardiovascular risk in this population; interventions are needed. Previously, we reported that a T2D-associated decrement in skeletal muscle oxidative flux is ameliorated with acute use of supplemental oxygen, suggesting that skeletal muscle oxygenation is rate-limiting to in vivo mitochondrial oxidative flux during exercise in T2D. We hypothesized that single-leg exercise training (SLET) would improve the T2D-specific impairment in in vivo mitochondrial oxidative flux during exercise. Adults with (n = 19) and without T2D (n = 22) with similar body mass indexes and levels of physical activity participated in two weeks of SLET. Following SLET, in vivo oxidative flux measured by 31 P-MRS increased in participants with T2D, but not people without T2D, measured by the increase in initial phosphocreatine synthesis (P = 0.0455 for the group × exercise interaction) and maximum rate of oxidative ATP synthesis (P = 0.0286 for the interaction). Additionally, oxidative phosphorylation increased in all participants with SLET (P = 0.0209). After SLET, there was no effect of supplemental oxygen on any of the in vivo oxidative flux measurements in either group (P > 0.02), consistent with resolution of the T2D-associated oxygen limitation previously observed at baseline in subjects with T2D. State 4 mitochondrial respiration also improved in muscle fibres ex vivo. Skeletal muscle vasculature content and calf blood flow increased in all participants with SLET (P < 0.0040); oxygen extraction in the calf increased only in T2D (P = 0.0461). SLET resolves the T2D-associated impairment of skeletal muscle in vivo mitochondrial oxidative flux potentially through improved effective blood flow/oxygen delivery.

Updated Reference Standards for Cardiorespiratory Fitness Measured with Cardiopulmonary Exercise Testing: Data from the Fitness Registry and the Importance of Exercise National Database (FRIEND)

OBJECTIVE

To provide updated reference standards for cardiorespiratory fitness (CRF) for the United States derived from cardiopulmonary exercise (CPX) testing when using a treadmill or cycle ergometer.

PATIENTS AND METHODS

Thirty-four laboratories in the United States contributed data to the Fitness Registry and the Importance of Exercise National Database. Analysis included 22,379 tests (16,278 treadmill and 6101 cycle ergometer) conducted between January 1, 1968, through March 31, 2021, from apparently healthy adults (aged 20 to 89 years). Percentiles of peak oxygen consumption for men and women were determined for each decade from 20 through 89 years of age for treadmill and cycle exercise modes, as well as when defining maximal effort as respiratory exchange ratio (RER) greater than or equal to 1.0 or RER greater than or equal to 1.1.

RESULTS

For both men and women, the 50^th percentile scores for each exercise mode decreased with age and were higher in men across all age groups and higher for treadmill compared with cycle CPX. The average rate of decline per decade over a 6-decade period was 13.5%, 4.0 mLO₂·kg^-1·min^-1 for treadmill CPX and 16.4%, 4.3 mLO₂·kg^-1·min^-1 for cycle CPX. Observationally, the mean peak oxygen consumption was similar whether using an RER criterion of greater than or equal to 1.0 or greater than or equal to 1.1 across the different test modes, ages, and for both sexes. The updated reference standards for treadmill CPX were 1.5 - 4.6 mLO₂·kg^-1·min^-1 lower compared with the previous 2015 standards whereas the updated cycling standards were generally comparable to the original 2017 standards.

CONCLUSION

These updated cardiorespiratory fitness reference standards improve the representativeness of the US population compared with the original standards.

Intermittent fasting & performance: The iFast clinical trial protocol

There is increasing evidence from animal and human studies suggesting that fasting can play a role in disease prevention, weight control and longevity. However, few studies have compared exercise performances in individuals adhering to an intermittent fasting (IF) in comparison to individuals who are not. Given the rising popularity of IF we aim to investigate whether this type eating pattern will improve cardiovascular performance over a period of 12 weeks through VO₂ max measurements in participants from a Lebanese community. Additionally, we will study the variation of different health parameters, physical performance and biomarkers potentially affected by IF. Participants will be recruited from a large university community and randomized into 4 arms. Baseline information will be collected from all participants, which includes biological, physical, nutritional, medical and psychological data. Two arms will follow a time-restricted fasting diet with and without physical exercise, one arm will exercise without fasting, and one will act as a control group. Throughout the study, measurements will be repeated, and data analysis will follow to evaluate results.

Benefits of Home-Based Exercise Training Following Critical SARS-CoV-2 Infection: A Case Report

In the current scenario, in which an elevated number of COVID-19 survivors present with severe physical deconditioning, exercise intolerance, persistent symptoms, and other post-acute consequences, effective rehabilitation strategies are of utmost relevance. In this study, we report for the first time the effect of home-based exercise training (HBET) in a survivor patient from critical COVID-19 illness. A 67-year-old woman who had critical COVID-19 disease [71 days of hospitalization, of which 49 days were in the intensive care unit (ICU) with invasive mechanical ventilation due to respiratory failure] underwent a 10-week HBET aiming to recovering overall physical condition. Before and after the intervention, we assessed cardiopulmonary parameters, skeletal muscle strength and functionality, fatigue severity, and self-reported persistent symptoms. At baseline (3 months after discharge), she presented with severe impairment in cardiorespiratory functional capacity (<50% age predicted VO2peak). After the intervention, remarkable improvements in VO2peak (from 10.61 to 15.48 mL·kg-1·min-1, Δ: 45.9%), oxygen uptake efficiency slope (OUES; from 1.0 to 1.3 L·min-1, Δ: 30.1%), HR/VO2 slope (from 92 to 52 bpm·L-1, Δ: -43.5%), the lowest VE/VCO2 ratio (from 35.4 to 32.9 L·min-1, Δ: -7.1%), and exertional dyspnea were observed. In addition, handgrip strength (from 22 to 27 kg, Δ: 22.7%), 30-s Sit-to-Stand (30-STS; from 14 to 16 repetitions, Δ:14.3%), Timed-Up-and-Go (TUG; from 8.25 to 7.01 s, Δ: -15%) performance and post-COVID functional status (PCFS) score (from 4 to 2) were also improved from baseline to post-intervention. Self-reported persistent symptoms were also improved, and Fatigue Severity Scale (FSS) score decreased (from 4 to 2.7) from baseline to post-intervention. This is the first evidence that a semi-supervised, HBET program may be safe and potentially effective in improving cardiorespiratory and physical functionality in COVID-19 survivors. Controlled studies are warranted to confirm these findings.

Effect of Equine-Assisted Activities and Therapies on Cardiorespiratory Fitness in Children with Cerebral Palsy: A Randomized Controlled Trial

Abstract Objectives: To determine the effects of an equine-assisted activities and therapies (EAAT) program on cardiorespiratory fitness (CRF) in children with cerebral palsy (CP). Design: An evaluator-blinded, parallel, two-arm, randomized controlled clinical trial with 1:1 randomization. Settings/Location: A tertiary university hospital and a local arena. Subjects: Forty-six children with CP (24 boys and 22 girls) classified as Gross Motor Function Classification System levels I, II, or III were included. Interventions: The EAAT program was conducted for 40 min twice a week for 16 weeks (32 lessons). Outcome measures: Clinical global impression scales, motor capacity, cardiopulmonary fitness, and habitual physical activity was measured on both groups before and after the 16-week period. Results: Changes in the Clinical Global Impression-Severity scale and Clinical Global Impression-Improvement scale scores were not different between the groups after the intervention. Analysis of covariance revealed statistically significant differences in Gross Motor Function Measure 66 (GMFM 66) (p < 0.05) and Pediatric Balance Scale (p < 0.001) in motor capacity and resting heart rate (HRrest) (p < 0.001) in CRF, between the EAAT group and the control group. Subgroup analysis using multiple linear regression analysis revealed that the GMFM 66 changes had a statistically significant effect on the HRrest changes in the EAAT group (p < 0.05). Conclusions: The present study showed decreased HRrest in children with CP after completing the 16-week EAAT program. This improvement was explained by the improvement of GMFM 66 in the EAAT group. Thus, EAAT may be among the endurance training programs that could be offered to children with CP to improve their CRF. Clinical Trial Registration number: NCT03870893.