Cardiorespiratory fitness assessment using risk-stratified exercise testing and dose-response relationships with disease outcomes

Plasma proteomic signatures for type 2 diabetes and related traits in the UK Biobank cohort

OBJECTIVE

The plasma proteome holds promise as a diagnostic and prognostic tool that can accurately reflect complex human traits and disease processes. We assessed the ability of proteins to predict type 2 diabetes and related traits.

STUDY DESIGN

We analyzed clinical, genetic, and proteomic data from three UK Biobank subcohorts for associations with truncal fat, estimated maximum oxygen consumption (VO2max), and type 2 diabetes. Using least absolute shrinkage and selection operator (LASSO) regression, we compared predictive performance of each trait between data types. The benefit of proteomic signatures (PSs) over the type 2 diabetes clinical risk score, QDiabetes was evaluated. Two-sample Mendelian randomization (MR) identified potentially causal proteins for each trait.

RESULTS

LASSO-derived PSs improved prediction of truncal fat and VO2max over clinical and genetic factors. We observed a modest improvement in type 2 diabetes prediction over the QDiabetes score when combining a PS derived for type 2 diabetes that was further augmented with fat- and fitness-associated PSs. Two-sample MR identified a few proteins as potentially causal for each trait.

CONCLUSION

Plasma PSs modestly improve type 2 diabetes prediction beyond clinical and genetic factors. Candidate causally associated proteins deserve further study as potential novel therapeutic targets for type 2 diabetes.

Cardiorespiratory Fitness, Body Composition, Diabetes, and Longevity: A 2-Sample Mendelian Randomization Study

CONTEXT

Cardiorespiratory fitness, commonly assessed as maximal volume of oxygen consumption (VO2max), has emerged as an important predictor of morbidity and mortality.

OBJECTIVE

We investigated the causality and directionality of the associations of VO2max with body composition, physical activity, diabetes, performance enhancers, and longevity.

METHODS

Using publicly available summary statistics from the largest genome-wide association studies publicly available, we conducted a bidirectional 2-sample Mendelian randomization (MR) study. Bidirectional MR tested directionality, and estimated the total causal effects, whereas multivariable MR (MVMR) estimated independent causal effects. Cardiorespiratory fitness (VO2max) was estimated from a submaximal cycle ramp test (N ≈ 70 000) and scaled to total body weight, and in additional analyses to fat-free mass (mL/min/kg).

RESULTS

Genetically predicted higher (per 1 SD increase) body fat percentage was associated with lower VO2max (β = -0.36; 95% CI: -0.40, -0.32, P = 6 × 10-77). Meanwhile, genetically predicted higher appendicular lean mass (β = 0.10; 95% CI: 0.08 to 0.13), physical activity (β = 0.29; 95% CI: 0.07 to 0.52), and performance enhancers (fasting insulin, hematocrit, and free testosterone in men) were all positively associated with VO2max (all P < .01). Genetic predisposition to diabetes had no effect on VO2max. MVMR showed independent causal effects of body fat percentage, appendicular lean mass, physical activity, and hematocrit on VO2max, as well as of body fat percentage and type 2 diabetes (T2D) on longevity. Genetically predicted VO2max showed no associations.

CONCLUSION

Cardiorespiratory fitness can be improved by favorable body composition, physical activity, and performance enhancers. Despite being a strong predictor of mortality, VO2max is not causally associated with T2D or longevity.

Impact of cycling cadence on physiological response during a cardiopulmonary exercise test

INTRODUCTION

The impact of cycling at different cadences on cardiopulmonary exercise test (CPET) measurements is poorly understood. We aimed to investigate whether higher cadences of pedalling led to meaningful changes in physiological endpoints.

METHODS

Study participants were recruited from healthy staff members working within three NHS trusts across England. At baseline, all participants completed a CPET at 60 rpm and then subsequently completed CPETs at cadences of 70, 80 and 90 rpm, allocated in a random order. To evaluate the mean differences in CPET measurements across the cadences, we used a one-way repeated measures analysis of variance. We then performed post hoc pairwise comparisons with Tukey correction to account for multiple testing.

RESULTS

Data collection took place between the 19 September 2023 and 9 April 2024. 25 participants had complete data at each cadence. 48% (12 of 25) were female, with a median (IQR) age of 30 years (27-41). There was no significant difference in peak V̇O2 across the cadences. Maximum achieved work rate was significantly different across the cadences (p=<0.001). The highest wattage was achieved at 60 rpm (221.2 watts±71.4) and lowest at 90 rpm (210.4 watts, ±77.2). End exercise ventilation increased with increasing cadence (p=0.013), with a mean of 97.6 L/min (±28.3) at 60 prm and 107.0 L/min (±33.9) at 90 prm. Breathing reserve decreased with increasing cadence (p=0.009), with a mean of 45.6 L/min (±28.8) at 60 rpm and 35.1 L/min (±23.5) at 90 rpm. There were minimal differences in other CPET parameters.

CONCLUSION

In a healthy population, higher cycling cadences increased ventilatory demand and reduced maximum work rate. This could have implications for CPETs in the clinical setting, where physiological responses to higher cadences may be more exaggerated.

Exercise Testing for Metabolic Flexibility: Time for Protocol Standardization

Metabolic syndrome (MetS) is a combination of risk factors that contribute to the development of many of today's chronic diseases. Rates of MetS continue to increase and it is now considered a worldwide epidemic. As with many chronic diseases it may take years for symptoms and the effects of MetS to manifest into severe health problems. Therefore, early detection is paramount A recently proposed method for the early detection of MetS is the assessment of an individual's metabolic flexibility during exercise. Metabolic flexibility is defined as the ability of the body to switch between energy substrates, primarily fats and carbohydrates, to produce energy and meet metabolic demand. This provides an indication of mitochondrial health, the possible beginning point of early insulin resistance and the development of MetS.Although there is widespread use of exercise and expired gas analysis to determine metabolic flexibility, there is no consensus on the appropriate guidelines, protocol, or interpretation of the subsequent data. Studies have used a variety of different protocols involving maximal and submaximal tests with step protocols ranging from 2 to 10 min, differences in data averaging, analysis, and stoichiometric equations, as well as variations in nutritional status of participants, and mode of exercise. This has led to considerable variation in reported results. Although the use of exercise to determine metabolic flexibility and act as a possible marker of early mitochondrial dysfunction holds significant promise, more work is required to determine the optimal protocol for clinical and research purposes.

Exercise and Fitness Quantification in Clinical Practice: Why and How; and Where Are We Going?

Exercise and fitness quantification is increasingly recognized as a critical component in clinical practice, particularly within preventive cardiology. In this article we explore the multifaceted importance of exercise quantification in clinical settings, addressing preventive care, cost-effectiveness, psychosocial benefits, treatment planning, and monitoring progress. Quantifying exercise habits allows clinicians to evaluate risk profiles, prescribe tailored interventions, and monitor patient progress. The methodologies for exercise quantification are discussed. In preventive cardiology, adherence to guidelines from organizations such as the American Heart Association, the European Society of Cardiology, and the Canadian Cardiovascular Society is emphasized, with particular focus on high-intensity interval training and the central role of physical therapists/kinesiologists. Special populations, such as weekend warriors, those reflecting the "fat and fit" concept, athletes, and those at risk of overtraining syndrome, are considered in prescribing exercise. Future directions in exercise and fitness quantification include the integration of advanced wearable technology, personalized medicine, telemedicine, and promotion of active, walkable communities. The incorporation of behavioral science is highlighted as a missing component that can enhance long-term adherence to exercise regimens through motivation, behavior change techniques, patient-centered approaches, and continuous monitoring and feedback. This comprehensive approach aims to optimize cardiovascular health and overall well-being through individualized, evidence-based exercise interventions that are both effective and sustainable.

Association of cardiorespiratory fitness with dementia risk across different levels of genetic predisposition: a large community-based longitudinal study

OBJECTIVE

We aimed to investigate the association of cardiorespiratory fitness (CRF) with cognitive function and dementia risk, taking genetic predisposition for dementia into account.

METHODS

Within the UK Biobank, 61 214 dementia-free participants aged 39-70 years were followed for up to 12 years. CRF score was estimated using a 6 min submaximal exercise test on a stationary bike and divided into tertiles (ie, low, moderate, and high; standardised by age and sex). Global cognitive function was evaluated at baseline. Dementia was identified based on medical history and medical records. Genetic predisposition for dementia was estimated using the polygenic risk score for Alzheimer's disease (PRSAD), tertiled as low, moderate, or high. Data were analysed using linear regression, Poisson regression, and Laplace regression.

RESULTS

Compared with low CRF, high CRF was related to better global cognitive function (β=0.05, 95% CI 0.04 to 0.07). Over the follow-up period, 553 individuals developed dementia. Compared with low CRF, the incidence rate ratio (IRR) of all dementia was 0.60 (95% CI 0.48 to 0.76) for high CRF, and the onset of all dementia was delayed by 1.48 (95% CI 0.58 to 2.39) years among people with high versus low CRF. Among people with a moderate/high polygenic risk score, high CRF attenuated all dementia risk by 35% (IRR 0.65, 95% CI 0.52 to 0.83).

CONCLUSION

High CRF is associated with better cognitive performance at baseline, and lower dementia risk long-term. High CRF could mitigate the impact of genetic predisposition on the development of dementia by 35%.

Fitness, Body Composition, and Health Behaviors in Long-Term Survivors of Adolescent and Young Adult Cancers

Purpose: To investigate cardiorespiratory fitness (CRF), body composition, health behaviors, and health-related quality of life (HRQoL) in adolescent and young adult cancer survivors (AYA-CS) compared with age-matched counterparts without a cancer diagnosis. Methods: This cross-sectional study recruited participants aged 15-25 years at the time of their cancer diagnosis and ≥ 5 years post-treatment. Participants completed cardiopulmonary exercise testing, dual-energy X-ray absorptiometry, food diaries, physical activity (PA), fatigue, and HRQoL questionnaires. Results: We recruited 22 participants aged 27.9 (standard deviation [SD] 3.3) years (54.5% female) and 7.2 (SD 2.2) years post-treatment. AYA-CS had lower CRF compared with age-matched norms (female 27.1 vs. 39.1 mL/kg/min, p ≤ 0.0001; male: 39.7 vs. 45.6 mL/kg/min, p = 0.04). Bone mineral density Z-scores were all within normal ranges; however, male AYA-CS had higher body fat percentage (male: 27.1% vs. 21.2%, p = 0.01) and a trend toward higher body fat percentage in female AYA-CS (32.2% vs. 29.8%, p = 03). AYA-CS had lower HRQoL, with no difference observed with fatigue. A higher proportion of AYA-CS met recommendations for weekly PA (36.4% vs. 27.3%, p = 0.34) and daily servings of fruit and vegetables (13.6% vs. 3.9%, p = 0.02) compared with normative data, demonstrating better health behaviors. A higher proportion of AYA-CS reported one or more chronic diseases compared with Australian normative data (63.7% vs. 41.5%, p = 0.04). Conclusions: AYA-CS exhibit significantly lower CRF and unfavorable body composition to age-matched counterparts. These health outcomes may adversely impact everyday functional performance and increase the risk of multimorbidity development. Interventions are needed to address these issues to improve health outcomes in AYA-CS.

Study on the stability and accuracy of the new Booster portable cardiopulmonary function meter

This study aims to assess the reliability and accuracy of a novel portable cardiopulmonary function meter, "Booster," developed by our research group, across various exercise intensities and modalities. The study was segmented into reliability and validity assessments. Twenty-two male participants underwent reliability testing, conducting two sequential tests on a treadmill while wearing the Booster to measure VO2 and VE among other parameters at increasing intensities. For validity testing, 64 participants were randomly divided into treadmill and cycle ergometer groups, with tests conducted using both the Booster and the Cortex Metalyzer 3B systems. Overall, the Booster demonstrated high retest reliability for VO2 and VE measurements during treadmill exercises, albeit showing poor consistency during rest and low-intensity exercise phases. Validity testing indicated no significant differences in VO2 and VE measurements between Booster and Cortex Metalyzer 3B across all exercise stages on both treadmill and cycle ergometer, suggesting good correlation. However, discrepancies in measurements between Booster and Cortex Metalyzer 3B were observed during rest and maximal exertion phases. The Booster exhibits commendable reliability and stability during most treadmill exercise phases and shows generally acceptable validity compared to the Cortex Metalyzer 3B system. Nonetheless, potential measurement discrepancies may occur during rest and maximal exertion conditions.

Effectiveness of an affect-adjusted, supervised, multimodal, online and home-based exercise group protocol for major depression: A randomized controlled trial

This randomized controlled trial investigated the effectiveness of an affect-adjusted, supervised, multimodal, online, and home-based exercise group protocol as an adjunct therapy to antidepressants on depressive symptoms, cardiorespiratory fitness, and side effects related to antidepressants in adults with major depression (MDD, diagnosed by a clinician). Depressive symptom scales were administered by a psychiatrist and self-reported. A health-related measure (i.e., cardiorespiratory fitness), was also administered. The exercise intervention was adjusted by perceived effort and affect (pleasure and enjoyment) toward exercise and lasted 12 weeks. In total, 59 adults with MDD were divided into two groups: the exercise-group (EG; exercise + pharmacotherapy) with 26-patients (76.9 % females, mean age 28.5 years) and the control-group (CG, pharmacotherapy) with 33-patients (78.7 % females, mean age 25.6 years). The EG had a lower dropout rate (15.3 %) than CG and an increase in cardiorespiratory fitness (CRF), which was not observed in the CG. Both groups showed a decrease in self-reported depressive symptoms. However, the EG had significantly lower depressive symptom scores at t1 and t2. The EG also had higher remission rates (t1, EG: = 42.3 % and CG = 27.2 %) and remission rates (t2, EG: = 72.7 % and CG = 48.1 %) than CG, which were maintained during the four month follow-up. Side effects from anti-depressant medication were larger in the EG compared to CG. Complementing usual care for MDD with exercise resulted in better clinical outcomes and supports the use of this type of exercise protocol in the clinical management of depression.

A prognostic molecular signature of hepatic steatosis is spatially heterogeneous and dynamic in human liver

Hepatic steatosis is a central phenotype in multi-system metabolic dysfunction and is increasing in parallel with the obesity pandemic. We use a translational approach integrating clinical phenotyping and outcomes, circulating proteomics, and tissue transcriptomics to identify dynamic, functional biomarkers of hepatic steatosis. Using multi-modality imaging and broad proteomic profiling, we identify proteins implicated in the progression of hepatic steatosis that are largely encoded by genes enriched at the transcriptional level in the human liver. These transcripts are differentially expressed across areas of steatosis in spatial transcriptomics, and several are dynamic during stages of steatosis. Circulating multi-protein signatures of steatosis strongly associate with fatty liver disease and multi-system metabolic outcomes. Using a humanized "liver-on-a-chip" model, we induce hepatic steatosis, confirming cell-specific expression of prioritized targets. These results underscore the utility of this approach to identify a prognostic, functional, dynamic "liquid biopsy" of human liver, relevant to biomarker discovery and mechanistic research applications.

Observational and genetic associations between cardiorespiratory fitness and age-related diseases: longitudinal analyses in the UK Biobank study

Background

Observational studies have indicated that increased cardiorespiratory fitness is associated with a decreased risk of cardiovascular disease (CVD), Alzheimer's disease (AD), and Parkinson's disease (PD). However, the causal mechanisms remain unclear. The objective of this study was to assess the role of fitness in the early detection and reduction of disease risk within the framework of predictive, preventive, and personalized medicine (PPPM/3PM).

Methods

The associations of fitness with CVD, AD, and PD were explored in a large cohort of up to 502,486 individuals between the ages of 40 and 69 years from the UK Biobank. Cox proportional hazards models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for the risk of CVD, AD, and PD among participants who completed a submaximal fitness test. Causality relationships were assessed via two-sample Mendelian randomization (MR).

Results

After a median of 11 years of follow-up, each 3.5 ml of O2⋅min-1⋅kg-1 increase in total body mass (equivalent to 1 metabolic equivalent of task (MET), approximately 0.5 standard deviations (SDs)) was associated with decreased risks of CVD (20.0%, 95% CI 17.6-22.3%), AD (31.9%, 95% CI 26.7-33.6%), and PD (21.2%, 95% CI 11.2-31.8%). After adjusting for obesity, the observational associations were attenuated. According to the MR analyses, fitness was associated with PD (OR IVW 0.937, 95% CI 0.897-0.978) and small vessel stroke (OR IVW 0.964, 95% CI 0.933-0.995).

Conclusion

Our results indicate that fitness has an effect on age-related diseases. Protective associations of higher fitness levels with the risk of CVD, AD, and PD were validated in this cohort study. These findings might be valuable for predicting, preventing, and reducing disease morbidity and mortality through primary prevention and healthcare in the context of PPPM.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13167-024-00382-4.

Plasma proteomic signatures for type 2 diabetes mellitus and related traits in the UK Biobank cohort

Aims/hypothesis

The plasma proteome holds promise as a diagnostic and prognostic tool that can accurately reflect complex human traits and disease processes. We assessed the ability of plasma proteins to predict type 2 diabetes mellitus (T2DM) and related traits.

Methods

Clinical, genetic, and high-throughput proteomic data from three subcohorts of UK Biobank participants were analyzed for association with dual-energy x-ray absorptiometry (DXA) derived truncal fat (in the adiposity subcohort), estimated maximum oxygen consumption (VO2max) (in the fitness subcohort), and incident T2DM (in the T2DM subcohort). We used least absolute shrinkage and selection operator (LASSO) regression to assess the relative ability of non-proteomic and proteomic variables to associate with each trait by comparing variance explained (R2) and area under the curve (AUC) statistics between data types. Stability selection with randomized LASSO regression identified the most robustly associated proteins for each trait. The benefit of proteomic signatures (PSs) over QDiabetes, a T2DM clinical risk score, was evaluated through the derivation of delta (Δ) AUC values. We also assessed the incremental gain in model performance metrics using proteomic datasets with varying numbers of proteins. A series of two-sample Mendelian randomization (MR) analyses were conducted to identify potentially causal proteins for adiposity, fitness, and T2DM.

Results

Across all three subcohorts, the mean age was 56.7 years and 54.9% were female. In the T2DM subcohort, 5.8% developed incident T2DM over a median follow-up of 7.6 years. LASSO-derived PSs increased the R2 of truncal fat and VO2max over clinical and genetic factors by 0.074 and 0.057, respectively. We observed a similar improvement in T2DM prediction over the QDiabetes score [Δ AUC: 0.016 (95% CI 0.008, 0.024)] when using a robust PS derived strictly from the T2DM outcome versus a model further augmented with non-overlapping proteins associated with adiposity and fitness. A small number of proteins (29 for truncal adiposity, 18 for VO2max, and 26 for T2DM) identified by stability selection algorithms offered most of the improvement in prediction of each outcome. Filtered and clustered versions of the full proteomic dataset supplied by the UK Biobank (ranging between 600-1,500 proteins) performed comparably to the full dataset for T2DM prediction. Using MR, we identified 4 proteins as potentially causal for adiposity, 1 as potentially causal for fitness, and 4 as potentially causal for T2DM.

Conclusions/Interpretation

Plasma PSs modestly improve the prediction of incident T2DM over that possible with clinical and genetic factors. Further studies are warranted to better elucidate the clinical utility of these signatures in predicting the risk of T2DM over the standard practice of using the QDiabetes score. Candidate causally associated proteins identified through MR deserve further study as potential novel therapeutic targets for T2DM.

Proteomic Risk Score of Increased Respiratory Susceptibility: A Multi-Cohort Study

RATIONALE

Accelerated decline in lung function is associated with incident COPD, hospitalizations and death. However, identifying this trajectory with longitudinal spirometry measurements is challenging in clinical practice.

OBJECTIVE

To determine whether a proteomic risk score trained on accelerated decline in lung function can assess risk of future respiratory disease and mortality.

METHODS

In CARDIA, a population-based cohort starting in young adulthood, longitudinal measurements of FEV1 percent predicted (up to six timepoints over 30 years) were used to identify accelerated and normal decline trajectories. Protein aptamers associated with an accelerated decline trajectory were identified with multivariable logistic regression followed by LASSO regression. The proteomic respiratory susceptibility score was derived based on these circulating proteins and applied to the UK Biobank and COPDGene studies to examine associations with future respiratory morbidity and mortality.

MEASUREMENTS AND RESULTS

Higher susceptibility score was independently associated with all-cause mortality (UKBB: HR 1.56, 95%CI 1.50-1.61; COPDGene: HR 1.75, 95%CI 1.63-1.88), respiratory mortality (UKBB: HR 2.39, 95% CI 2.16-2.64; COPDGene: HR 1.83, 95%CI 1.33-2.51), incident COPD (UKBB: HR 1.84, 95%CI 1.71-1.98), incident respiratory exacerbation (COPDGene: OR 1.11, 95%CI 1.03-1.20), and incident exacerbation requiring hospitalization (COPDGene: OR 1.18, 95%CI 1.08-1.28).

CONCLUSIONS

A proteomic signature of increased respiratory susceptibility identifies people at risk of respiratory death, incident COPD, and respiratory exacerbations. This susceptibility score is comprised of proteins with well-known and novel associations with lung health and holds promise for the early detection of lung disease without requiring years of spirometry measurements.

Physical Activity, Cardiorespiratory Fitness, and the Obesity Paradox with Consideration for Racial and/or Ethnic Differences: A Broad Review and Call to Action

Despite decades of extensive research and clinical insights on the increased risk of all-cause and disease-specific morbidity and mortality due to obesity, the obesity paradox still presents a unique perspective, i.e., having a higher body mass index (BMI) offers a protective effect on adverse health outcomes, particularly in people with known cardiovascular disease (CVD). This protective effect may be due to modifiable factors that influence body weight status and health, including physical activity (PA) and cardiorespiratory fitness (CRF), as well as non-modifiable factors, such as race and/or ethnicity. This article briefly reviews the current knowledge surrounding the obesity paradox, its relationship with PA and CRF, and compelling considerations for race and/or ethnicity concerning the obesity paradox. As such, this review provides recommendations and a call to action for future precision medicine to consider modifiable and non-modifiable factors when preventing and/or treating obesity.

Levels of circulating angiotensin-converting enzyme 2 are affected by acute exercise and correlate with markers of physical fitness in male athletes

While under physiological conditions angiotensin-converting enzyme 2 (ACE2) is an antagonist of vasoconstrictive agents in the renin-angiotensin-aldosterone system (RAAS), in the context of SARS coronavirus 2 (SARS-CoV-2) ACE2 serves as the gateway into cells. Furthermore, RAAS has previously been shown to be influenced by exercise training and is suggested to be involved in skeletal muscle mass maintenance. Given this connection, the investigation of circulating ACE2 plasma protein concentration before and following acute and chronic endurance and resistance exercise could increase the understanding of the implications of the exposure of athletes to SARS-CoV-2. Therefore, this study investigated levels of circulating ACE2 in lifelong high-level trained endurance and resistance athletes and control subjects in response to either acute endurance or resistance exercise. Results show no baseline differences in absolute ACE2 concentration between groups, but a strong negative correlation with levels of fitness and positive correlation with BMI in control subjects. Furthermore, acute endurance exercise significantly increased ACE2 levels across all groups, but only in the strength group in response to resistance exercise. This indicates that circulating ACE2 plasma levels are influenced by levels of fitness and health, and that acute endurance exercise has a stronger effect on plasma ACE2 levels than resistance exercise.

Network analysis for inter-relationships of the suboptimal health status with depression and anxiety during the COVID-19 pandemic: A perspective of predictive, preventive, and personalized health

BACKGROUND

The Coronavirus Disease-2019 (COVID-19) pandemic has had a profound impact on suboptimal health status, depression, and anxiety, necessitating a comprehensive understanding of their inter-relationships at the national level. This study aims to investigate the inter-relationships among suboptimal health status, depression, and anxiety using a network analysis approach.

METHODS

We conducted a national survey between June 20 and August 31, 2022. Three network models were constructed and analyzed to independently examine the inter-relationships among suboptimal health status, depression, and anxiety.

RESULTS

A total of 26,152 participants were included in this study. The study network analysis indicated that item 9 (i.e., Slow response) exhibited the highest node strength within the suboptimal health status questionnaire-short form (SHSQ-SF) network, followed by item 5 (i.e., Breathlessness at rest). Additionally, positive correlations were observed between depression and anxiety severity and most of the SHSO-SF items.

CONCLUSIONS

This study provided valuable insights into inter-relationships between suboptimal health status, depression, and anxiety, informing the development of comprehensive intervention strategies for the general population. These findings have important implications for promoting the well-being and mental health of individuals during and beyond the COVID-19 pandemic.

Proteomic analysis of cardiorespiratory fitness for prediction of mortality and multisystem disease risks

Despite the wide effects of cardiorespiratory fitness (CRF) on metabolic, cardiovascular, pulmonary and neurological health, challenges in the feasibility and reproducibility of CRF measurements have impeded its use for clinical decision-making. Here we link proteomic profiles to CRF in 14,145 individuals across four international cohorts with diverse CRF ascertainment methods to establish, validate and characterize a proteomic CRF score. In a cohort of around 22,000 individuals in the UK Biobank, a proteomic CRF score was associated with a reduced risk of all-cause mortality (unadjusted hazard ratio 0.50 (95% confidence interval 0.48-0.52) per 1 s.d. increase). The proteomic CRF score was also associated with multisystem disease risk and provided risk reclassification and discrimination beyond clinical risk factors, as well as modulating high polygenic risk of certain diseases. Finally, we observed dynamicity of the proteomic CRF score in individuals who undertook a 20-week exercise training program and an association of the score with the degree of the effect of training on CRF, suggesting potential use of the score for personalization of exercise recommendations. These results indicate that population-based proteomics provides biologically relevant molecular readouts of CRF that are additive to genetic risk, potentially modifiable and clinically translatable.

Dose-response relationship between weekly physical activity level and the frequency of colds in Chinese middle-aged and elderly individuals

Background

Engaging in appropriate physical activity can significantly lower the risk of various diseases among middle-aged and older adults. Investigating optimal levels of physical activity (PA) is crucial for enhancing the health of this demographic. This study aims to explore the dose-response relationship between weekly PA levels and the frequency of colds among Chinese middle-aged and elderly individuals, identifying the necessary PA level to effectively diminish the risk of colds.

Methods

We conducted a cross-sectional study using a web-based survey targeting individuals aged 40 and older (n = 1, 683) in China. The survey collected information on PA and the frequency of colds. Data was analyzed using Kruskal-Wallis test and the χ2 test. We explored the dose-response relationship between weekly PA and cold frequency over the past year through an ordered multivariate logistic regression model and a restricted cubic spline model.

Results

(1) Brisk walking emerged as the preferred physical exercise for those over 40. The findings suggest that engaging in moderate (odds ratio (OR) = 0.64, P < 0.001, 95% confidence interval (CI) [0.50-0.81]) and high (OR = 0.64, P < 0.001, 95% CI [0.51-0.79]) levels of PA weekly significantly reduces the risk of catching a cold. Individuals with one (OR = 1.47, P < 0.001, 95% CI [1.20-1.80]) or multiple chronic diseases (OR = 1.56, P < 0.001, 95% CI [1.21-2.00]) were at increased risk. Those residing in central (OR = 1.64, P < 0.001, 95% CI [1.33-02.01]) and western China (OR = 1.49, P = 0.008, 95% CI [1.11-02.00]) faced a higher risk compared to their counterparts in eastern China. (2) According to the restricted cubic spline model, adults who experienced one cold in the past year had a weekly PA level of 537.29 metabolic equivalent-minutes per week (MET-min/wk) with an OR value of 1. For those reporting two or more colds, the PA level was 537.76 MET-min/wk with an OR of 1.

Conclusions

(1) Brisk walking is the most favored exercise among the Chinese middle-aged and elderly, with the prevalence of colds being affected by the number of chronic diseases and the geographic location. (2) Regular, moderate exercise is linked to a lower risk of colds. To effectively reduce cold frequency, it is recommended that middle-aged and elderly Chinese individuals engage in a minimum of 538 MET-min/wk of exercise.

Cardiorespiratory responses: Pilates compared to different walking speeds in healthy adults

BACKGROUND

The impact of a single-session Pilates exercise on cardiorespiratory fitness and metabolic parameters is still uncertain.

AIMS

The aim of this study was to examine the cardiorespiratory changes during a single-session Pilates exercise and compare cardiorespiratory fitness-related parameters with walking at different speeds on a treadmill, at low (3.2 kph) and moderate intensities (4.8 kph).

METHODS

Cardiorespiratory responses were measured with a cardiopulmonary exercise test device in 31 healthy young adults at rest, during a single Pilates session, walking at 3.2 kph and walking at 4.8 kph. The study design employed a cross-over design. Participants were randomly assigned to two experimental groups: a Pilates training session following treadmill walking or treadmill walking following a Pilates training session.

RESULTS

Mean MET, oxygen and energy consumption during Pilates were similar to walking at 3.2 kph (p > 0.05), but significantly lower than walking at 4.8 kph (p < 0.05). The mean heart rate during Pilates was higher than walking at 3.2 kph (p < 0.05), but similar to walking at 4.8 kph (p > 0.05). Significantly higher carbohydrate metabolism was used during Pilates compared to walking (p < 0.05).

CONCLUSION

The cardiopulmonary responses to a single Pilates session are similar to walking at a speed of 3.2 kph but lower than walking at 4.8 kph. These results indicate that while Pilates may not generate sufficient cardiopulmonary changes to enhance cardiorespiratory fitness as a moderate-intensity exercise in healthy young adults, it may still offer other benefits such as improvements in flexibility, core strength, and posture.

A prognostic molecular signature of hepatic steatosis is spatially heterogeneous and dynamic in human liver

Metabolic dysfunction-associated steatotic liver disease (MASLD) prevalence is increasing in parallel with an obesity pandemic, calling for novel strategies for prevention and treatment. We defined a circulating proteome of human MASLD across ≈7000 proteins in ≈5000 individuals from diverse, at-risk populations across the metabolic health spectrum, demonstrating reproducible diagnostic performance and specifying both known and novel metabolic pathways relevant to MASLD (central carbon and amino acid metabolism, hepatocyte regeneration, inflammation, fibrosis, insulin sensitivity). A parsimonious proteomic signature of MASLD was associated with a protection from MASLD and its related multi-system metabolic consequences in >26000 free-living individuals, with an additive effect to polygenic risk. The MASLD proteome was encoded by genes that demonstrated transcriptional enrichment in liver, with spatial transcriptional activity in areas of steatosis in human liver biopsy and dynamicity for select targets in human liver across stages of steatosis. We replicated several top relations from proteomics and spatial tissue transcriptomics in a humanized "liver-on-a-chip" model of MASLD, highlighting the power of a full translational approach to discovery in MASLD. Collectively, these results underscore utility of blood-based proteomics as a dynamic "liquid biopsy" of human liver relevant to clinical biomarker and mechanistic applications.

Observational and genetic associations between cardiorespiratory fitness and cancer: a UK Biobank and international consortia study

BACKGROUND

The association of fitness with cancer risk is not clear.

METHODS

We used Cox proportional hazards models to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for risk of lung, colorectal, endometrial, breast, and prostate cancer in a subset of UK Biobank participants who completed a submaximal fitness test in 2009-12 (N = 72,572). We also investigated relationships using two-sample Mendelian randomisation (MR), odds ratios (ORs) were estimated using the inverse-variance weighted method.

RESULTS

After a median of 11 years of follow-up, 4290 cancers of interest were diagnosed. A 3.5 ml O2⋅min-1⋅kg-1 total-body mass increase in fitness (equivalent to 1 metabolic equivalent of task (MET), approximately 0.5 standard deviation (SD)) was associated with lower risks of endometrial (HR = 0.81, 95% CI: 0.73-0.89), colorectal (0.94, 0.90-0.99), and breast cancer (0.96, 0.92-0.99). In MR analyses, a 0.5 SD increase in genetically predicted O2⋅min-1⋅kg-1 fat-free mass was associated with a lower risk of breast cancer (OR = 0.92, 95% CI: 0.86-0.98). After adjusting for adiposity, both the observational and genetic associations were attenuated.

DISCUSSION

Higher fitness levels may reduce risks of endometrial, colorectal, and breast cancer, though relationships with adiposity are complex and may mediate these relationships. Increasing fitness, including via changes in body composition, may be an effective strategy for cancer prevention.

Periodized Aerobic Training between Thresholds Improves Submaximal Cardiorespiratory Parameters in Octogenarians

BACKGROUND AND AIMS

The worldwide aging population is expanding, with more individuals living into their 80s. Physiological functions decline gradually with age, compounded by sedentary lifestyles. Incorporating physical activity into daily routine is crucial for maintaining independence. This study aimed to assess a periodized high-intensity aerobic training program (PEZO-BT) in octogenarians, focusing on submaximal ergospirometry effects.

METHODS

A total of 48 non-frail octogenarian subjects (12 females, 36 males) were randomized into control and intervention groups. All subjects underwent submaximal cardiopulmonary exercise testing with gas analysis at baseline, stopping after the respiratory compensation point (RCP). Our intervention group completed a 14-week PEZO-BT aerobic training program. The outcomes were oxygen consumption at first ventilatory threshold (VO2AT), ventilatory efficiency slope (VE/VCO2), oxygen uptake efficiency slope (OUES), cardiorespiratory optimal point (COP), oxygen pulse change (ΔVO2/HR) from anaerobic threshold (AT) to respiratory compensation point (RCP), and power output at anaerobic threshold (POAT).

RESULTS

Mixed ANOVA examined time and treatment effects. If significance emerged, post hoc t-tests were used to compare significances between groups. The homogeneity of variance was assessed using Levene's test. Chi-square tests compared ergospirometry criteria and ventilatory performance within groups. The mean differences at post intervention were significant in VO2AT (p < 0.001), VE/VCO2 (p < 0.001), ΔVO2/HR (p < 0.05), and POAT (p < 0.001), while OUES and COP were not significant (p > 0.05). However, clinical effects were observed in the entire intervention group.

CONCLUSIONS

Training improved exercise capacity and workload. Overall, this periodic aerobic and high-intensity interval training (HIIT) program yielded significant improvements in cardiorespiratory fitness (CRF) in previously untrained octogenarians with and without comorbidities. The findings suggest implications for promoting long-term healthy aging.

COVID-19 reduces cardiorespiratory fitness even months after a mild to moderate acute phase: a retrospective cohort study

BACKGROUND

COVID-19 survivors may experience long-term health problems, including deterioration of cardiorespiratory fitness (CRF), as demonstrated by several cross-sectional studies that compared the results of cardiopulmonary exercise tests (CPET) performed only after COVID-19 with predicted values. This study aimed to analyze a change in CRF between repeated CPETs in response to suffered COVID-19.

METHODS

A total of 127 healthcare workers (HCWs; mean age 55.7 years) underwent two CPETs with a mean interval of 762 days. Forty HCWs suffered from COVID-19 (mild to moderate severity) in the interim (321 days before the second CPET), and 87 HCWs formed a control group. Mixed-effects regression with multiple adjustment and interaction terms was used for two response variables - maximum oxygen uptake (VO2 max) and power output.

RESULTS

Between both CPETs, mean VO2 max decreased statistically significantly in the COVID-19 subgroup (by 3.12 mL/kg/min, p = .034) and insignificantly in controls (by 0.56 mL/kg/min, p = .412). The proportion of HCWs achieving predicted VO2 max decreased from 75.9% to 59.5% (p = .161) in COVID-19 survivors, while it increased from 73.8% to 81% (p = .274) in controls. COVID-19 (β = -0.66, p = .014) and body mass index (β = -0.49, p < .001) were independent negative predictors of VO2 max change. COVID-19 was not associated with a change in power output.

CONCLUSIONS

On the basis of repeated CPETs, COVID-19 significantly, albeit rather modestly, reduces CRF almost one year after infection. The reduction persists even after the acute phase with mild or moderate severity.

Causal associations between cardiorespiratory fitness and type 2 diabetes

Higher cardiorespiratory fitness is associated with lower risk of type 2 diabetes. However, the causality of this relationship and the biological mechanisms that underlie it are unclear. Here, we examine genetic determinants of cardiorespiratory fitness in 450k European-ancestry individuals in UK Biobank, by leveraging the genetic overlap between fitness measured by an exercise test and resting heart rate. We identified 160 fitness-associated loci which we validated in an independent cohort, the Fenland study. Gene-based analyses prioritised candidate genes, such as CACNA1C, SCN10A, MYH11 and MYH6, that are enriched in biological processes related to cardiac muscle development and muscle contractility. In a Mendelian Randomisation framework, we demonstrate that higher genetically predicted fitness is causally associated with lower risk of type 2 diabetes independent of adiposity. Integration with proteomic data identified N-terminal pro B-type natriuretic peptide, hepatocyte growth factor-like protein and sex hormone-binding globulin as potential mediators of this relationship. Collectively, our findings provide insights into the biological mechanisms underpinning cardiorespiratory fitness and highlight the importance of improving fitness for diabetes prevention.

Association between exercise load, resting heart rate, and maximum heart rate and risk of future ST-segment elevation myocardial infarction (STEMI)

OBJECTIVE

This study aimed to examine the association between exercise workload, resting heart rate (RHR), maximum heart rate and the risk of developing ST-segment elevation myocardial infarction (STEMI).

METHODS

The study included all participants from the UK Biobank who had undergone submaximal exercise stress testing. Patients with a history of STEMI were excluded. The allowed exercise load for each participant was calculated based on clinical characteristics and risk categories. We studied the participants who exercised to reach 50% or 35% of their expected maximum exercise tolerance. STEMI was adjudicated by the UK Biobank. We used Cox regression analysis to study how exercise tolerance and RHR were related to the risk of STEMI.

RESULTS

A total of 66 949 participants were studied, of whom 274 developed STEMI during a median follow-up of 7.7 years. After adjusting for age, sex, blood pressure, smoking, forced vital capacity, forced expiratory volume in 1 s, peak expiratory flow and diabetes, we noted a significant association between RHR and the risk of STEMI (p=0.015). The HR for STEMI in the highest RHR quartile (>90 beats/min) compared with that in the lowest quartile was 2.92 (95% CI 1.26 to 6.77). Neither the maximum achieved exercise load nor the ratio of the maximum heart rate to the maximum load was significantly associated with the risk of STEMI. However, a non-significant but stepwise inverse association was noted between the maximum load and the risk of STEMI.

CONCLUSION

RHR is an independent predictor of future STEMI. An RHR of >90 beats/min is associated with an almost threefold increase in the risk of STEMI.

Resting heart rate is a population-level biomarker of cardiorespiratory fitness: The Fenland Study

INTRODUCTION

Few large studies have evaluated the relationship between resting heart rate (RHR) and cardiorespiratory fitness. Here we examine cross-sectional and longitudinal relationships between RHR and fitness, explore factors that influence these relationships, and demonstrate the utility of RHR for remote population monitoring.

METHODS

In cross-sectional analyses (The UK Fenland Study: 5,722 women, 5,143 men, aged 29-65y), we measured RHR (beats per min, bpm) while seated, supine, and during sleep. Fitness was estimated as maximal oxygen consumption (ml⋅min-1⋅kg-1) from an exercise test. Associations between RHR and fitness were evaluated while adjusting for age, sex, adiposity, and physical activity. In longitudinal analyses (6,589 participant subsample), we re-assessed RHR and fitness after a median of 6 years and evaluated the association between within-person change in RHR and fitness. During the coronavirus disease-2019 pandemic, we used a smartphone application to remotely and serially measure RHR (1,914 participant subsample, August 2020 to April 2021) and examined differences in RHR dynamics by pre-pandemic fitness level.

RESULTS

Mean RHR while seated, supine, and during sleep was 67, 64, and 57 bpm. Age-adjusted associations (beta coefficients) between RHR and fitness were -0.26, -0.29, and -0.21 ml⋅kg-1⋅beat-1 in women and -0.27, -0.31, and -0.19 ml⋅kg-1⋅beat-1 in men. Adjustment for adiposity and physical activity attenuated the RHR-to-fitness relationship by 10% and 50%, respectively. Longitudinally, a 1-bpm increase in supine RHR was associated with a 0.23 ml⋅min-1⋅kg-1 decrease in fitness. During the pandemic, RHR increased in those with low pre-pandemic fitness but was stable in others.

CONCLUSIONS

RHR is a valid population-level biomarker of cardiorespiratory fitness. Physical activity and adiposity attenuate the relationship between RHR and fitness.

Descriptive Epidemiology of Cardiorespiratory Fitness in UK Adults: The Fenland Study

INTRODUCTION

Cardiorespiratory fitness (CRF) is rarely measured in population studies. Most studies of CRF do not examine differences by population subgroups or seasonal trends. We examined how estimated CRF levels vary by anthropometric, sociodemographic, and behavioral characteristics in a population-based cohort of UK adults (the Fenland Study).

METHODS

We used a validated submaximal exercise test to obtain CRF estimates (CRF estimated ) in 5976 women and 5316 men, residing in the East of England. CRF estimated was defined as estimated maximal oxygen consumption per kilogram total body mass (V̇O 2 max tbm ) and fat-free mass (V̇O 2 max ffm ). Descriptive statistics were computed across anthropometric and sociodemographic characteristics, and across the year. Progressive multivariable analyses were performed to examine associations with physical activity energy expenditure (PAEE) and body mass index (BMI).

RESULTS

Mean ± SD V̇O 2 max tbm was lower in women (35.2 ± 7.5 mL·min -1 ·kg -1 ) than men (41.7 ± 7.3 mL·min -1 ·kg -1 ) but V̇O 2 max ffm was similar (women: 59.2 ± 11.6 mL·min -1 ·kg -1 ; men: 62.0 ± 10.3 mL·min -1 ·kg -1 ). CRF estimated was inversely associated with age but not after adjustment for PAEE. People in more physically demanding jobs were fitter compared with those in sedentary jobs, but this association was attenuated in women and reversed in men after adjustment for total PAEE. Physical activity energy expenditure and BMI were positively associated with CRF estimated at all levels of adjustment when expressed relative to fat-free mass. CRF estimated was 4% higher in summer than in winter among women, but did not differ by season among men.

CONCLUSIONS

CRF estimated was inversely associated with age but less steeply than anticipated, suggesting older generations are comparatively fitter than younger generations. Physical activity energy expenditure and BMI were stronger determinants of the variance in CRF estimated than other characteristic including age. This emphasizes the importance of modifiable physical activity behaviors in public health interventions.

Physical activity lowers the risk for acute respiratory infections: Time for recognition

Physical inactivity is a well-established risk factor for chronic diseases, such as cardiovascular disease, cancer, and diabetes mellitus. There is a growing awareness that physical inactivity should also be regarded as a risk factor for acute respiratory infections (ARIs). ARIs, such as the common cold, influenza, pneumonia, and coronavirus disease 2019 (COVID-19), are among the most pervasive diseases on earth and cause widespread morbidity and mortality. Evidence in support of the linkage between ARIs and physical inactivity has been strengthened during the COVID-19 pandemic because of increased scientific scrutiny. Large-scale studies have consistently reported that the risk for severe COVID-19 outcomes is elevated in cohorts with low physical activity and/or physical fitness, even after adjusting for other risk factors. The lowered risk for severe COVID-19 and other ARIs in physically active groups is attributed to exercise-induced immunoprotective effects, including enhanced surveillance of key immune cells and reduced chronic inflammation. Scientific consensus groups, including those who submitted the Physical Activity Guidelines for Americans, have not yet given this area of research the respect that is due. It is time to add "reduced risk for ARIs" to the "Exercise is Medicine" list of physical activity-related health benefits.

Equipment-free, unsupervised high intensity interval training elicits significant improvements in the physiological resilience of older adults

Background

Reduced cardiorespiratory fitness (CRF) is an independent risk factor for dependency, cognitive impairment and premature mortality. High-intensity interval training (HIIT) is a proven time-efficient stimulus for improving both CRF and other facets of cardiometabolic health also known to decline with advancing age. However, the efficacy of equipment-free, unsupervised HIIT to improve the physiological resilience of older adults is not known.

Methods

Thirty independent, community-dwelling older adults (71(SD: 5) years) were randomised to 4 weeks (12 sessions) equipment-free, supervised (in the laboratory (L-HIIT)) or unsupervised (at home (H-HIIT)) HIIT, or a no-intervention control (CON). HIIT involved 5, 1-minute intervals of a bodyweight exercise each interspersed with 90-seconds recovery. CRF, exercise tolerance, blood pressure (BP), body composition, muscle architecture, circulating lipids and glucose tolerance were assessed at baseline and after the intervention period.

Results

When compared to the control group, both HIIT protocols improved the primary outcome of CRF ((via anaerobic threshold) mean difference, L-HIIT: +2.27, H-HIIT: +2.29, both p < 0.01) in addition to exercise tolerance, systolic BP, total cholesterol, non-HDL cholesterol and m. vastus lateralis pennation angle, to the same extent. There was no improvement in these parameters in CON. There was no change in diastolic BP, glucose tolerance, whole-body composition or HDL cholesterol in any of the groups.

Conclusions

This is the first study to show that short-term, time-efficient, equipment-free, HIIT is able to elicit improvements in the CRF of older adults irrespective of supervision status. Unsupervised HIIT may offer a novel approach to improve the physiological resilience of older adults, combating age-associated physiological decline, the rise of inactivity and the additional challenges currently posed by the COVID-19 pandemic.

Trial registration

This study was registered at clinicaltrials.gov and coded: NCT03473990.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12877-022-03208-y.

Sub Maximal Ergospirometry Parameters in Untrained Non-Frail Octogenarian Subjects

Background and Objectives: The prevalence of chronic diseases increases with age, and in octogenarian elderly, a cardiorespiratory test with gas analysis is more effective in determining the risk of mortality than applying the conventional risk factors. Materials and Methods: 25 untrained non-frail octogenarian subjects (four men) performed a submaximal test with gas analysis, which was stopped after the second ventilatory threshold (VT2) was reached. The variables analyzed were oxygen consumption at the first threshold (VO2 VT1); ventilatory class (VE/VCO2); oxygen uptake efficiency slope (OUES); cardiorespiratory optimal point (COP); oxygen pulse difference between VT2 and VT1 (diff. VO2/HR VT2-VT1). Results: the variables were classified categorically based on cut-off points present in the literature, where the variable with the highest percentage of altered cases was dif. VO2/HR VT2-VT1 at 48%; followed by VO2 VT1 at 40%, OUES at 36%, COP at 32%, and VE/VCO2 at 24%. Chi-square analysis between the measured parameters defined that normal and altered variables were related to each other, except for the variable VE/VCO2 and OUES. Conclusions: it was found that the main altered variable was the oxygen pulse and the least altered variable was VCO2/VCO2; there was only a statistically significant difference in a pair of OUES vs. VE/VCO2 variables.