This year marks the 10-year anniversary of the American Heart Association’s (AHA) policy statement “The Importance of Cardiorespiratory Fitness in the United States: The Need for a National Registry.” In my teaching and lecturing, I have often commented that the field of exercise physiology is a very young area of science. Much of the foundations for exercise physiology in the United States were set from the work of D.B. Dill and colleagues at the Harvard Fatigue Laboratory in the 1930s.
A fundamental measurement in exercise physiology is that of maximal (or peak) oxygen uptake (VO2max); this year also coincides with the 100-year anniversary of the work of Nobel Prize-winning scientist A.V. Hill’s studies that first developed the procedures to make the measurements for VO2max.
Cardiorespiratory fitness (or CRF), one of the components of physical fitness, refers to the capacity of the cardiopulmonary systems to deliver oxygen to skeletal muscles to power physical activities and is measured as VO2max. Most of the research over the first 50 years since Hill’s original publication was focused on performance or functional ability. However, in the 1960s and ’70s, physicians, including Bruno Balke, Robert Bruce, and Kenneth Cooper, began recognizing the cardiovascular health-related aspects of CRF. Undoubtedly, the paper that put CRF in the forefront as an important marker of health, “Physical fitness and all-cause mortality. A prospective study of healthy men and women,” was published in JAMA in 1989 by Dr. Steven Blair and colleagues with the Cooper Clinic cohort.
Over the next 20+ years, research established that CRF was indeed a key marker for health; however, a limiting concern was the lack of reference standards for interpreting CRF measurements. Thus, the AHA policy statement published in 2013 led to the development of the Fitness Registry and the Importance of Exercise National Database (FRIEND).
The FRIEND registry initiated the process to acquire exercise test data from clinics and laboratories throughout the United States and released an initial set of reference standards for directly measured VO2max for tests performed on treadmills or cycle ergometers. FRIEND continues to acquire exercise test data from clinics and laboratories and last year published updated reference standards for CRF. The FRIEND reports have been selected by the editors of the American College of Sports Medicine’s® (ACSM’s) Guidelines for Exercise Testing and Prescription as the reference standards for interpreting CRF values. The FRIEND registry has proven to be a great resource for research on other variables obtained during a maximal exercise test, as can be noted by doing a search on PubMed using the term “Fitness Registry and the Importance of Exercise National Database.” Additionally, FRIEND has been involved with an effort to develop global reference standards for CRF.
Finally, the recognition of the importance of CRF was summarized in the 2016 scientific statement by the AHA entitled “Importance of Assessing Cardiorespiratory Fitness in Clinical Practice: A Case for Fitness as a Clinical Vital Sign.” This statement concludes that “the addition of CRF for risk classification presents health professionals with unique opportunities to improve patient management and to encourage lifestyle-based strategies designed to reduce cardiovascular risk.”
ACSM has been a leader in advancing the importance of physical fitness. It is now clearly understood that CRF is one of the most important markers of health and should be regularly assessed in the clinical setting. Exercise professionals are well positioned to advance this message and are the key personnel that provide the measurement of CRF.
Do you know your CRF level? If not, it is time to seek out a facility that can provide this vital information for you.
Related CEC Courses:
POLAR and ACSM Presents: Heart Rate Monitoring Assessment Course (6 CECs)
Industry Presented Webinar: Essential Elements of Heart Rate Based Training – Key Concepts & Practical Applications for Training (2 CECs)
Dr. Lenny Kaminsky directed the Clinical Exercise Physiology Program and Laboratory and the Adult Physical Fitness Program at Ball State University (BSU) for over 25 years and is currently the director emeritus of BSU’s Fisher Institute of Health and Well-Being. He is one of the primary collaborators of the Ball State Longitudinal Lifestyle Study (BALLST) and one of the co-founders of the Fitness Registry for the Importance of Exercise National Database (FRIEND) Registry for Cardiorespiratory Fitness. He has served as editor of multiple ACSM publications and regularly contributes to scientific writing groups including the American Heart Association’s (AHA) scientific statement supporting cardiorespiratory fitness as a vital sign and the American Association of Cardiovascular and Pulmonary Rehabilitation’s (AACVPR) Statement on Progression of Exercise Training. He is the Editor-in-Chief of AACVPR’s Journal of Cardiopulmonary Rehabilitation and Prevention and the commentary editor of the ACSM Bulletin.
Viewpoints presented in ACSM Bulletin commentaries reflect opinions of the authors and do not necessarily represent positions or policies of ACSM. Authors who have received financial or other considerations from a commercial entity associated with their topic must disclose such relationships at the time they accept an invitation to write for the ACSM Bulletin.
