Symbolic illustration of declining cardiorespiratory health.

Declining Fitness Levels: Are We Facing a Cardiorespiratory Crisis?

Elliot Brynn in Health & Wellness November 2026 • 4 min read.

"A recent study reveals a disturbing trend in Saudi Arabia, highlighting the urgent need to address declining cardiorespiratory fitness and its potential impact on healthcare costs."

In an era defined by sedentary lifestyles and increasingly urbanized environments, the importance of cardiorespiratory fitness cannot be overstated. Cardiorespiratory fitness, often measured by exercise capacity and workload, is a key indicator of overall health and well-being. Recent research presented at a Brazilian cardiology conference sheds light on a concerning trend: a significant decline in cardiorespiratory fitness levels within the Saudi Arabian population, with potential ramifications for public health and healthcare costs.

This article will delve into the details of this study, exploring the methodologies used, the key findings, and the implications for individuals and healthcare systems. We'll also consider the potential factors contributing to this decline and discuss strategies to promote improved cardiorespiratory fitness in an increasingly challenging world.

Reader Intent/ Public Interest: Explanatory Queries, Combining a core concept with a domain, Action-Oriented.

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Standard Approach

Measuring Cardiorespiratory Fitness

Cardiorespiratory fitness (CRF) can be assessed through exercise testing, with reference standards organized by cardiovascular disease category and testing modality. One 2024 study description also identifies a non-exercise method for estimating CRF and examining its associations with all-cause and cardiovascular mortality across eight population-based cohorts. Comparing CRF across populations is challenging when exercise testing is unstandardized; canonical estimation methods may also assume steady-state exercise while applying group-level estimates. Updated reference standards are intended to support the clinical interpretation of CRF.

The Study: Unveiling the Decline in Cardiorespiratory Fitness

Symbolic illustration of declining cardiorespiratory health.

The study, presented at the Society of Cardiology of the State of São Paulo (SOCESP) web-conference, analyzed data collected in Saudi Arabia to assess cardiorespiratory fitness trends over a period of several years. Researchers prospectively collected data on clinical characteristics and stress variables from patients undergoing exercise stress tests. They specifically measured exercise workload, expressed in estimated METS (Metabolic Equivalents), using the Quinton treadmill controller. This allowed them to quantify the exercise capacity of the participants and track changes over time.

A key aspect of the study was the inclusion of both patients who were able to exercise and those who were unable to do so, requiring pharmacological stress tests. This provided a comprehensive picture of the population's overall cardiorespiratory health. The results revealed several significant findings:

Decline in Exercise Capacity: A significant decrease in the percentage of patients achieving more than 10 or 12 METS over the analysis period (p<0.001). This indicates a reduction in the ability of individuals to perform moderate to vigorous intensity physical activity.
Increased Reliance on Pharmacological Stress Testing: A significant increase in the rate of pharmacological stress testing over the study period (p<0.0001), suggesting that a larger proportion of patients were unable to complete a traditional exercise stress test due to poor fitness levels.
Decrease in Body Mass Index (BMI): Among patients who were able to exercise, there was a slight decrease in mean body mass index over time from 30.1 to 28.9kg/m2 (p<0.001). While seemingly positive, this finding needs to be interpreted cautiously in the context of the overall decline in fitness.

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Latest Research

What Recent Reviews Say About Fitness

A review of exercise capacity describes it as a spectrum reflecting functional capacity and dynamic cardiac remodeling alongside respiratory and skeletal muscle systems. In endurance athletes, the relationship between increased physical activity, greater cardiac mass and volumes, and improved CRF is well established. A 2026 narrative review examines cardiorespiratory responses to both acute exercise and chronic exercise training. Another scientific statement reviews the clinical and physiologic basis for exercise prescription, including physical-activity volume and CRF levels associated with cardioprotective benefits.

Comparison

Comparing Exercise Training Approaches

An updated systematic review and meta-analysis compares high-intensity interval training (HIIT) with moderate-intensity continuous training (MICT) for exercise capacity and health-related quality of life in people with coronary artery disease. A 2025 study aims to assess the effectiveness of HIIT and MICT, the optimal intervention duration for different training intensities, and modalities that may improve cardiorespiratory function and exercise capacity in patients. Exercise training is defined as structured exercise intended to improve or maintain CRF, muscle strength, health, functional independence, athletic performance, or a combination of these outcomes.

The study also emphasized a parallel initiative by SOCESP to disseminate cardiovascular medicine knowledge and prevention guidelines through web conferences in Brazilian municipalities. This highlights the potential of leveraging technology to address healthcare challenges and promote healthier lifestyles.

Addressing the Crisis: A Call to Action

The findings of this study serve as a wake-up call, highlighting the urgent need to address declining cardiorespiratory fitness levels. This requires a multi-faceted approach involving individuals, healthcare professionals, and policymakers. Promoting physical activity, encouraging healthy eating habits, and creating supportive environments are crucial steps in reversing this concerning trend. By prioritizing cardiorespiratory fitness, we can improve overall health outcomes, reduce healthcare costs, and build a healthier future for generations to come.

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Expert View

Fitness Across Functional Capacity

Exercise capacity spans a range of functional ability and reflects changing cardiac remodeling together with respiratory and skeletal muscle systems. The relationship between increased physical activity, increased cardiac mass and volumes, and improved CRF is well established in endurance athletes. A systematic review focused on people with lymphedema or lipedema searched for studies using terms related to those conditions and cardiorespiratory or cardiopulmonary fitness and capacity. Its search was limited to English-language articles.

Future Outlook

Tracking Fitness Trends at Work

A 2021 study noted reports of a negative CRF trend in the general population, while observing that trends by occupational group were missing. It set out to examine CRF trends over the preceding 20 years among Swedish workers in different occupational groups and to provide a prognosis of future trends. The source describes this as a study aim; the provided information does not include its results or the projected direction or size of future changes.

How other evidence frames fitness trends

Evidence from Swedish workers describes different patterns by sex and age group: some groups showed no change in VO2max, while decreases were reported in younger and middle-aged men. This underlines why a trend should not be generalized across populations without matching the groups and measures.^[1]

A review of pandemic-era fitness trends among European children and adolescents presents reduced physical activity as a plausible pathway to declines, linked to disrupted routines and access to structured activities. It also notes that speed levels recovered more quickly than endurance, so fitness components may follow different trajectories.^[2]

What monitoring and measurement still need to clarify

Would sustained national and international surveillance show whether fitness trends persist across populations, particularly where current trend data are absent?^[3]
How much of a population trend reflects habitual activity, and how much reflects inherited differences or the choice of fitness measure? The cited review attributes nearly half of CRF variance to genetics and identifies habitual activity as the primary modifiable influence on the remainder.^[4]

Questions about fitness and health

How is cardiorespiratory fitness commonly expressed?

It is commonly expressed as maximum or peak oxygen consumption per kilogram of body mass, or in metabolic equivalents of task. When direct measurement is not feasible, non-exercise prediction equations with reasonable validity are also available.^[4]

How is cardiorespiratory fitness related to mortality?

The cited overview reports that each one-MET higher CRF level was associated with an 11%–17% reduction in all-cause mortality. This is an association, not evidence that raising fitness by itself guarantees a particular outcome.^[4]

Terms used to describe fitness

Metabolic equivalent of task: MET^[4]

Sources

About this Article -

Written with AI assistance from published research, and reviewed by the Mystum team. See our About page for more information.

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Everything You Need To Know

1

What exactly is cardiorespiratory fitness, and why is it so important?

Cardiorespiratory fitness is a measure of how well your heart and lungs work together to supply oxygen to your muscles during physical activity. It's often gauged by exercise capacity and workload. The study in Saudi Arabia found that exercise capacity, measured in estimated METS, is declining. A decline in this indicates a reduced ability to perform moderate to vigorous intensity physical activity. This decline is significant because it is a key indicator of overall health and well-being, impacting the ability to perform daily tasks and increasing the risk of various health problems.

2

How did the study measure cardiorespiratory fitness?

The study's methodology involved analyzing data from exercise stress tests conducted in Saudi Arabia. Researchers collected data on clinical characteristics and stress variables from patients. They used the Quinton treadmill controller to measure exercise workload, expressed in estimated METS. The study included both patients who could exercise and those who required pharmacological stress tests. The results revealed a decline in exercise capacity and an increased reliance on pharmacological stress testing. This comprehensive approach provided a thorough assessment of the population's cardiorespiratory health.

3

What were the main findings of the study regarding cardiorespiratory fitness?

The study found several key issues. Firstly, a significant decrease in the percentage of patients achieving more than 10 or 12 METS was observed, indicating a reduction in the ability to perform moderate to vigorous intensity physical activity. Secondly, there was an increase in pharmacological stress testing, suggesting more patients were unable to complete traditional exercise stress tests. Thirdly, the Body Mass Index decreased slightly. The findings highlight a decline in cardiorespiratory fitness within the Saudi Arabian population, impacting overall health.

4

What are the potential consequences of declining cardiorespiratory fitness?

The implications of declining cardiorespiratory fitness are far-reaching. It impacts public health by increasing the risk of cardiovascular diseases, diabetes, and other chronic conditions. It increases healthcare costs due to the increased need for medical interventions and treatment for these conditions. The study's findings serve as a call to action, emphasizing the importance of addressing this trend through interventions that promote physical activity, healthy eating, and supportive environments. Ultimately, improving cardiorespiratory fitness can lead to improved health outcomes and reduce healthcare expenditures.

5

What steps can be taken to address the decline in cardiorespiratory fitness?

Addressing the decline in cardiorespiratory fitness requires a multi-faceted approach. This includes promoting physical activity through regular exercise and encouraging healthy eating habits. Creating supportive environments that facilitate physical activity, such as accessible parks and recreational facilities, is also crucial. Healthcare professionals and policymakers play a vital role in implementing strategies to promote healthier lifestyles. Leveraging technology, like the SOCESP web conferences, can also help in disseminating knowledge and prevention guidelines. By prioritizing cardiorespiratory fitness, we can improve health outcomes and reduce healthcare costs.