Elsevier

Progress in Cardiovascular Diseases

Volume 62, Issue 1, January–February 2019, Pages 76-82
Progress in Cardiovascular Diseases

Determining Cardiorespiratory Fitness With Precision: Compendium of Findings From the FRIEND Registry

https://doi.org/10.1016/j.pcad.2018.10.003Get rights and content

Abstract

Healthy living (HL) behaviors and characteristics are central to both preventing and treating a myriad of chronic diseases; a key HL characteristic is cardiorespiratory fitness (CRF). Knowing an individual's CRF provides vital information when assessing health status and formulating a plan of care. Normative reference values as well as thresholds that denote varying degrees of health and future risk exist for measures of CRF. However, improving upon the precision of CRF reference standards according to key factors as well as precision in how CRF assessments can be used to assess health status and prognosis is needed. The current review will: 1) provide an overview of current approaches to CRF assessment and interpretations; 2) describe more recent efforts to improve upon the precision of CRF values; and 3) describe the Fitness Registry and the Importance of Exercise: A National Data Base (FRIEND) for the precision of CRF as a clinical measure.

Section snippets

Current methods for CRF assessment and interpretation

Understanding the factors that influence differences in CRF is important. Data from the HERITAGE study suggested that heritable factors, after adjusting for age and sex, were associated with ~50% of the variation in CRF in adults.9 Physical activity (PA), especially in the form of exercise training (ET), is the key HL behavior that can modify an individual's CRF.10., 11., 12. Accordingly, international public health statements strongly recommend regular PA worldwide.13 However, it is important

Value of CPX-derived CRF as the standard

Until the 1980s, exercise capacity was generally expressed as an estimated value based on maximal work rate achieved on a treadmill or cycle ergometer. The CPX method was generally limited to the domain of research physiologists and pulmonary medicine. The concept that estimated exercise capacity was an important marker of risk was demonstrated in the seminal Coronary Artery Surgery Studies (CASS) conducted in the late 1970s and early 1980s.29 The CASS investigators observed that among patients

Establishment and the importance of FRIEND

Along with the recognition of the value of CRF in recent years has come a need to develop ways to incorporate CRF into clinical, public health, and research settings. This need was recognized in a 2013 policy statement by the AHA entitled, “The Importance of Cardiorespiratory Fitness in the United States: The Need for a National Registry”.3 This scientific statement was part of an initiative to develop a national registry termed “Fitness Registry and the Importance of Exercise: A National Data

Reference standards from the FRIEND registry

The FRIEND registry provided an ideal opportunity to improve upon existing reference standards for CRF.55 The FRIEND data has advantages over previous efforts addressing this issue, including the fact that it overcomes many of the shortcomings cited in the Paap and Takken review,46 the American Thoracic Society Guidelines,21 and the AHA Scientific Statement on CPX.17 The FRIEND registry includes a large and diverse sample of healthy men and women in the US whose exercise tests met objectively

Conclusions

CRF is now considered a vital sign. As described in the current review, there is a need to improve the precision by which CRF is assessed and used to evaluate current health status and future risk. Moreover, efforts by FRIEND have helped to advance the precision of CRF prediction and normative values. As these efforts continue, the information obtained from a CRF assessment will become even more valuable to health professionals who are charged with optimizing outcomes for individuals under

Statement of conflict of interest

None of the authors have any conflicts of interests with regard to this publication.

Disclosures

L. Kaminsky serves as a Scientific Advisor for ENDO Medical, Inc.

Acknowledgement

The authors thank all the clinics and laboratories that have provided data for the FRIEND registry.

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    Statement of Conflict of Interest: see page 81.

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