Cardiorespiratory Fitness Assessment and Exercise Therapy: Why We Need This

A holistic approach to chronic-disease prevention and treatment often includes exercise therapy as an essential modality. Exercise is generally considered a healthy activity, with few exceptions, and its application is a logical addition to any health program. However, being told to exercise does not always inspire an individual. One way to help motivate is to understand the direct benefits of exercise on your health condition. Through a licensed holistic health-care provider, such as a naturopathic doctor, you can undergo two assessments that are an easy and effective tool for exercise adaptation: strength and cardiorespiratory fitness (CRF). The purpose of this article is to illustrate the value of CRF assessment as a motivational tool for the simple yet effective treatment modality: exercise therapy! Furthermore, you will learn here that CRF and its objective measures, such as V̇O2 max, are not just an assessment for athletes. Because the science of CRF is just emerging, CRF is not a standard assessment in health-care offices, so it is important to find a trusted provider who is skilled and offers this assessment as part of an integrative care program.

What is CRF?

CRF is defined as the ability of the circulatory and respiratory systems to supply oxygen to the tissues during sustained physical activity. It is measured as V̇O2 max or maximal oxygen uptake during intense exercise¹. CRF has been a focus of academic and clinical study for decades in the fields of cardiology, pulmonology, neurology, aging, metabolic health, oncology, and athletic performance. Due to the high clinical value of the evidence obtained during this period for CRF’s association with reduced mortality, the American Heart Association (AHA) made the decision, in 2016, to release a scientific statement positioning CRF as a “vital sign.” AHA’s intention was to encourage clinicians to make CRF a standard part of clinical encounters. ²

The decision of the AHA to make this recommendation was based on a series of key findings from randomized controlled trials (RCTs), cohort studies, case-control studies, and epidemiological data.³ Low CRF is associated with increased all-cause mortality risk and predicts mortality as strongly as very-well-established risk factors such as cigarette smoking, hypertension, high cholesterol, and type 2 diabetes mellitus.⁴ This includes increased incidence and mortality from cardiovascular disease, cancer, and Alzheimer’s disease, the three most prominent detriments to human longevity.^5,6,7

CRF and Exercise Therapy

Improving CRF through exercise therapy has been shown to improve survival after cardiovascular events, reduce the risk of cancer development and recurrence, reduce surgical risk and benefit the postsurgical recovery period, as well as delay the onset of dementia.⁸ Using aerobic exercise to train CRF leads to lower visceral adiposity, improved insulin sensitivity, and lower levels of inflammation; it enables the achievement of more favorable lipid and lipoprotein profiles; and it lowers blood pressure.⁹ The physiologic benefits span the metabolic, endocrinologic, cardio, and pulmonary systems.

What Does the Assessment Involve?

To measure CRF, licensed health-care practitioners use a cardiopulmonary exercise test (CPX), which provides incredible value on disease prevention as it gives an objective look at heart, lung, and mitochondrial wellness. The test can be completed using a stationary bike or treadmill and requires a clinical-grade metabolic analysis device to capture breath-by-breath data. The test begins with a three-minute warm-up and proceeds to a custom ramp-style test which increases in difficulty each minute until the patient reaches exhaustion. Throughout the test, V̇O2 usage and V̇CO2 expiration measurements are made in conjunction with heart rate. A two-minute cool-down concludes the test, where heart rate and respiratory rate return to baseline. Total test time, including instruction period, parameter check, and testing, is approximately 45 minutes.

CPX provides a baseline assessment of cardiorespiratory function for the implementation of a holistic heart-healthy plan. Having some objective measurements of lung and heart health helps improve compliance and motivation for exercise therapy. Follow-ups on progress and evaluations of V̇O2 max are generally recommended every 12 weeks.

Throughout a CPX assessment, measured values include tidal volume, breathing frequency, minute ventilation, V̇O2 pulse, V̇O2 breathing frequency, total calories burned per minute, calories from carbohydrate, and calories from fat. Key markers obtained for use in prescription exercise include metabolic efficiency, fat-burning efficiency, anaerobic threshold, and ventilatory threshold. These results inform an evidence-based, individualistic exercise program that may include resistance training, high-intensity interval training (HIIT/Tabata), and medium-intensity continuous training.

A Whole Metabolic Effect

Some terms to consider:

• Metabolic efficiency refers to caloric burn during movement and informs us about how well calories are burning during exercise. The value highlights active metabolism, overall fitness, and exercise efficiency.
• Fat-burning efficiency reflects the burning of fat by the mitochondria during exercise, a key value for weight loss.
• Anaerobic threshold is the heart rate and intensity at which the body transitions into anaerobic metabolism as a large part of the body’s energy generation.
• The ventilatory threshold is the exercise intensity at which physical activity starts to be considered a workout.

Conclusion

Cardiorespiratory fitness (CRF) is a valuable predictor of overall wellness, for disease prevention, for relief from the worsening of a chronic condition, and for the promotion of health-span and lifespan. It can be assessed through a cardiopulmonary exercise test (CPX) as part of an integrative care such as naturopathy.

The ongoing obesity academic epidemic, reliance on pharmaceutical intervention for cardiovascular-disease risk reduction, expensive surgeries, and rising type 2 diabetes encourage a simple, inexpensive tool as a holistic approach to metabolic wellness and prevention of cardiovascular illness. Aerobic fitness prescriptions should be detailed, properly tracked, and fairly evaluated. Cardiorespiratory fitness (CRF) testing allows us to do just that. The side effect? Better mood, energy, and sleep!