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

Unraveling the link between cardiorespiratory fitness and cancer: a state-of-the-art review

Cardiorespiratory fitness (CRF) not only reflects an individual's capacity to perform physical activities but also encapsulates broader effects on the basic biology of aging. This review aims to summarize the evidence on the influence of CRF on overall and site-specific cancer risks. It delves into the biological mechanisms through which CRF may exert its effects, explores the clinical implications of these findings, identifies gaps in the current evidence base, and suggests directions for future research. The synthesis of findings reveals that higher CRF levels (general threshold of > 7 METs) are consistently associated with a reduced risk of a range of cancers, including head and neck, lung, breast, gastrointestinal, particularly pancreatic and colorectal, bladder, overall cancer incidence and mortality, and potentially stomach and liver, bile duct, and gall bladder cancers. These inverse associations between CRF and cancer risk do not generally differ across age groups, sex, race, or adiposity, suggesting a universal protective effect of CRF. Nonetheless, evidence linking CRF with skin, mouth and pharynx, kidney, and endometrial cancers is limited and inconclusive. Conversely, higher CRF levels may be potentially linked to an increased risk of prostate cancer and hematological malignancies, such as leukemia and myeloma, although the evidence is still not conclusive. CRF appears to play a significant role in reducing the risk of several cancers through various biological mechanisms, including inflammation reduction, immune system enhancement, hormonal regulation, and metabolic improvements. Overall, enhancing CRF through regular physical activity offers a vital, accessible strategy for reducing cancer risk and extending the health span. Future research should aim to fill the existing evidence gaps regarding specific cancers and elucidate the detailed dose-response relationships between CRF levels and cancer risk. Studies are also needed to elucidate the causal relationships and mechanistic pathways linking CRF to cancer outcomes.

Reverse epidemiology of obesity paradox: Fact or fiction?

Obesity paradox refers to the clinical observation that when acute cardiovascular decompensation occurs, patients with obesity may have a survival benefit. This apparently runs counter to the epidemiology of obesity, which may increase the risk for non-communicable diseases (NCDs). The scientific community is split on obesity paradox, with some supporting it, while others call it BMI paradox. This review: (a) defines the obesity paradox, and its proposed role in overall mortality in NCDs; (b) delineates evidence for and against obesity paradox; (c) presents the importance of using different indices of body mass to assess the risk in NCDs; (d) examines the role of metabolically healthy obesity in obesity paradox, and emerging importance of cardio-respiratory fitness (CRF) as an independent predictor of CVD risk and all-cause mortality in patients with/without obesity. Evidence suggests that the development of obesity and insulin resistance are influenced by genetic (or ethnic) make up and dietary habits (culture) of the individuals. Hence, this review presents lean diabetes, which has higher total CVD and non-CVD mortality as compared to diabetics with obesity and the possibility of maternal factors programming cardiometabolic risk during fetal development, which may lead to a paradigm shift in our understanding of obesity.

Assessing older adult physical activity levels in clinical settings: The modified PAVS for older adults

BACKGROUND

Participating in recommended levels of physical activity (PA) is critical for preventing functional decline, falls, and frailty, making it essential to identify older adults not meeting national PA guidelines. However, guidance on assessing older adult PA levels, particularly in clinical settings, is lacking. This article presents an overview of clinically feasible PA assessment tools for older adults, identifies gaps in current tools, and provides recommendations on addressing these gaps.

METHODS

We conducted a literature review on clinically feasible PA assessment tools, suggested modifications to an existing PA assessment for older adult patients, and highlighted opportunities for integrating the modified PA assessment tool in clinical settings.

RESULTS

We identified 16 PA assessment tools used in clinical settings. The most widely used tool is the Physical Activity Vital Sign (PAVS), which has been successfully integrated into several electronic health records (EHR) and clinical practices. Most tools, including the PAVS, primarily focus on aerobic activities, with limited consideration for strength and balance. We recommend the use of a Modified PAVS for Older Adults that includes items on muscle-strengthening and balance activities to better align with national PA guidelines. We then identified several existing opportunities for broad implementation of the Modified PAVS for Older Adults within clinical settings.

CONCLUSIONS

Widespread integration of the Modified PAVS for Older Adults will better support healthcare providers in identifying individuals not meeting national PA recommendations, assisting them in prescribing tailored PA prescriptions and better connecting their patients to appropriate resources and professionals for further support.

High sensitivity troponins and mortality in the population with metabolic dysfunction-associated steatotic liver disease

Given the global high prevalence of MASLD and its poor CVD prognosis, it is essential to perform risk stratification for MASLD patients. The specific impact of High Sensitivity Troponins (hs-cTn ) on mortality in MASLD patients remains unexplored.  The NHANES databases from 1999 to 2004, which include data on high-sensitivity cardiac troponin (hs-cTn) levels and comorbidities, were linked with the most recent mortality dataset. Myocardial injury was determined using the 99th upper reference limits (URL) for hs-cTn.  Our study included 3460 MASLD patients. The mean follow-up duration was 192 months, during which 1074 (23%) MASLD participants died from all-cause mortality, and 363 (7.3%) died from CVD mortality. Our findings indicate that MASLD patients with elevated levels of hs-cTnT (> 99th URL) exhibit increased risks of all-cause mortality [adjusted hazard ratio (aHR) = 1.93] and CVD mortality (aHR = 2.4). Similar results were observed for hs-cTnI, where the aHRs for all-cause mortality and CVD mortality were 2.03 and 2.97, respectively. Furthermore, we identified a nonlinear dose-response relationship between hs-cTn levels and the risk of mortality (P for nonlinearity < 0.001).  Our findings suggest that hs-cTn can predict mortality risk in MASLD, aiding clinicians in risk-stratifying this population. Therefore, we recommend considering hs-cTn detection in individuals with MASLD to effectively assess their future mortality risk.

Protein Supplementation Increases Adaptations to Low-Volume, Intra-Session Concurrent Training in Untrained Healthy Adults: A Double-Blind, Placebo-Controlled, Randomized Trial

Combined endurance and resistance training, also known as "concurrent training", is a common practice in exercise routines. While concurrent training offers the benefit of targeting both cardiovascular and muscular fitness, it imposes greater physiological demands on the body compared to performing each modality in isolation. Increased protein consumption has been suggested to support adaptations to concurrent training. However, the impact of protein supplementation on responses to low-volume concurrent training is still unclear. Forty-four untrained, healthy individuals (27 ± 6 years) performed two sessions/week of low-volume high-intensity interval training on cycle ergometers followed by five machine-based resistance training exercises for 8 weeks. Volunteers randomly received (double-blinded) 40 g of whey-based protein (PRO group) or an isocaloric placebo (maltodextrin, PLA group) after each session. Maximal oxygen consumption (VO2max) and overall fitness scores (computed from volunteers' VO2max and one-repetition maximum scores, 1-RM) significantly increased in both groups. The PRO group showed significantly improved 1-RM in all major muscle groups, while the PLA group only improved 1-RM in chest and upper back muscles. Improvements in 1-RM in leg muscles were significantly greater in the PRO group versus the PLA group. In conclusion, our results indicate that adaptations to low-volume concurrent training, particularly leg muscle strength, can be improved with targeted post-exercise protein supplementation in untrained healthy individuals.

Non-exercise estimated cardiorespiratory fitness and incident type 2 diabetes in adults

AIM(S)

To examine the association between non-exercise estimated cardiorespiratory fitness (eCRF) and incident type 2 diabetes.

METHODS

In a sample of 13,616 men and women without diabetes at baseline, incident type 2 diabetes were determined as fasting plasma glucose level ≥ 7 mmol/l (126 mg/dL), self-report, or insulin usage at follow-up. eCRF was calculated in metabolic equivalents (METs) at baseline using sex-specific algorithms, including physical activity, smoking status, age, body mass index, waist circumference, and resting heart rate. Cox regression models were performed, and hazard ratios (HRs), 95 % confidence intervals (CIs), and p values were reported.

RESULTS

Each 1-MET unit increase in eCRF was associated with an 11 % lower risk of incident type 2 diabetes (p < 0.0001). Men in the upper and middle eCRF tertiles were at 46 % (95 % CI, 0.42-0.68) and 29 % (95 % CI, 0.57-0.88) lower risk of incident type 2 diabetes compared to the lower eCRF tertile (p < 0.0001). For women, there were no significant findings between eCRF tertiles and incident type 2 diabetes (p ≥ 0.11 for all).

CONCLUSIONS

Higher eCRF was associated with a lower incidence of type 2 diabetes in men. Further research needs to examine the association between eCRF and type 2 diabetes in women.

Physical Activity Participation among Children and Youth with Mental Health Symptoms: Clinician Perspectives

BACKGROUND/OBJECTIVES

Physical activity supports mental health and well-being in children and youth. However, there are significant barriers to physical activity participation among individuals impacted by mental health disorders. This study investigates these barriers through the perspective of mental health clinicians who support children and youth.

METHODS

Fourteen mental health clinicians, including registered professional psychologists, psychotherapists, and social workers, were interviewed in a semi-structured format. Qualitative content analysis was performed to identify key themes, including both barriers and facilitators to physical activity.

RESULTS

Content analysis revealed that clinicians perceive both internal and external barriers and facilitators to their clients' participation in physical activity. Barriers included intrapersonal factors, such as the presence of depression, anxiety, or eating disorder symptoms; lack of motivation; and negative self-talk, as well as factors related to the influence of caregivers, financial limitations, screen time use, environmental and cultural factors, and lack of time. Facilitators included enjoyment of physical activity, knowledge about the benefits of physical activity, and caregiver participation.

CONCLUSIONS

Mental health clinicians demonstrated clear knowledge about the barriers to and facilitators of their clients' participation in physical activity. These findings provide valuable insights that can be used to support children and youth experiencing mental health difficulty to access the beneficial effects of physical activity.

Estimated Cardiorespiratory Fitness and Metabolic Risks

This review focuses on the emerging evidence for the association between non-exercise fitness testing, estimated cardiorespiratory fitness (eCRF), and metabolic risk factors. Given the challenges associated with directly measuring cardiorespiratory fitness (CRF) in large populations, eCRF presents a practical alternative for predicting metabolic health risks. A literature search identified seven relevant cohort studies from 2020 to 2024 that investigated the association of eCRF with hypertension, hyperglycemia, dyslipidemia, and obesity. This review consistently demonstrates an inverse relationship between higher eCRF and a lower incidence of metabolic risks, which is in line with CRF cohort studies. It highlights the importance of low eCRF as a primordial indicator for metabolic risks and underscores the potential for broader application. Future research directions should include exploring eCRF's predictive ability across diverse populations and health outcomes and testing its real-world applicability in healthcare and public health settings.

Global status of cardiorespiratory fitness and physical activity - Are we improving or getting worse?

Despite heightened recognition of the importance of cardiorespiratory fitness (CRF) to cardiovascular (CV) health, along with updated international consensus guidelines for physical activity (PA) and sedentary behavior (SB), significant proportions of the global adult population are physically inactive, and do not meet the threshold for CRF. Physical inactivity is considered a surrogate for low CRF given that the former is defined as not reaching the recommended minimum level of PA per week to derive a health benefit. Physical inactivity remains a major global public health problem despite decades of work by various United Nations agencies, and members of the international community to improve PA levels. Given the common coupling between physical inactivity and poor health status, it is reasonable to suggest that for a significant proportion of the global population, CRF is compromised by physical inactivity. This poses a longer-term risk to morbidity and mortality. Here we provide an indicative summary of the global status of CRF and PA and reference the implications for global health. We briefly reference opportunities moving forward, including reinforcement of the importance of engaging in movement from an early age, discouraging SB, and taking a life course approach to optimise healthy living for all.

Cloud-Based Machine Learning Platform to Predict Clinical Outcomes at Home for Patients With Cardiovascular Conditions Discharged From Hospital: Clinical Trial

BACKGROUND

Hospitalizations account for almost one-third of the US $4.1 trillion health care cost in the United States. A substantial portion of these hospitalizations are attributed to readmissions, which led to the establishment of the Hospital Readmissions Reduction Program (HRRP) in 2012. The HRRP reduces payments to hospitals with excess readmissions. In 2018, >US $700 million was withheld; this is expected to exceed US $1 billion by 2022. More importantly, there is nothing more physically and emotionally taxing for readmitted patients and demoralizing for hospital physicians, nurses, and administrators. Given this high uncertainty of proper home recovery, intelligent monitoring is needed to predict the outcome of discharged patients to reduce readmissions. Physical activity (PA) is one of the major determinants for overall clinical outcomes in diabetes, hypertension, hyperlipidemia, heart failure, cancer, and mental health issues. These are the exact comorbidities that increase readmission rates, underlining the importance of PA in assessing the recovery of patients by quantitative measurement beyond the questionnaire and survey methods.

OBJECTIVE

This study aims to develop a remote, low-cost, and cloud-based machine learning (ML) platform to enable the precision health monitoring of PA, which may fundamentally alter the delivery of home health care. To validate this technology, we conducted a clinical trial to test the ability of our platform to predict clinical outcomes in discharged patients.

METHODS

Our platform consists of a wearable device, which includes an accelerometer and a Bluetooth sensor, and an iPhone connected to our cloud-based ML interface to analyze PA remotely and predict clinical outcomes. This system was deployed at a skilled nursing facility where we collected >17,000 person-day data points over 2 years, generating a solid training database. We used these data to train our extreme gradient boosting (XGBoost)-based ML environment to conduct a clinical trial, Activity Assessment of Patients Discharged from Hospital-I, to test the hypothesis that a comprehensive profile of PA would predict clinical outcome. We developed an advanced data-driven analytic platform that predicts the clinical outcome based on accurate measurements of PA. Artificial intelligence or an ML algorithm was used to analyze the data to predict short-term health outcome.

RESULTS

We enrolled 52 patients discharged from Stanford Hospital. Our data demonstrated a robust predictive system to forecast health outcome in the enrolled patients based on their PA data. We achieved precise prediction of the patients' clinical outcomes with a sensitivity of 87%, a specificity of 79%, and an accuracy of 85%.

CONCLUSIONS

To date, there are no reliable clinical data, using a wearable device, regarding monitoring discharged patients to predict their recovery. We conducted a clinical trial to assess outcome data rigorously to be used reliably for remote home care by patients, health care professionals, and caretakers.

2023 update: The importance of cardiorespiratory fitness in the United States

The American Heart Association issued a Policy Statement in 2013 that characterized the importance of cardiorespiratory fitness (CRF) as an essential marker of health outcomes and specifically the need for increased assessment of CRF. This statement summarized the evidence demonstrating that CRF is "one of the most important correlates of overall health status and a potent predictor of an individual's future risk of cardiovascular disease." Subsequently, this Policy Statement led to the development of a National Registry for CRF (Fitness Registry and the Importance of Exercise: A National Data Base [FRIEND]) which established normative reference values for CRF for adults in the United States (US). This review provides an overview of the progress made in the past decade to further our understanding of the importance of CRF, specifically related to prevention and for clinical populations. Additionally, this review overviews the evolvement and additional uses of FRIEND and summarizes a hierarchy of assessment methods for CRF. In summary, continued efforts are needed to expand the representation of data from across the US, and to include data from pediatric populations, to further develop the CRF Reference Standards for the US as well as further develop Global CRF Reference Standards.