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 (VO_2max); 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 VO_2max. 

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 VO_2max. 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 VO_2max 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.  

Nitrate supplementation has consistently been shown to benefit exercise performance due to its capacity to increase nitric oxide (NO), a signaling molecule that plays an important role in skeletal muscle function during exercise. Once ingested, nitrate is converted to nitrite via anaerobic bacteria in the oral cavity and nitrite is converted to NO especially under conditions of low oxygen availability and low pH, such as those that may be found in skeletal muscle during exercise. Inorganic nitrate is considered by the International Olympic Committee as one of only five dietary supplements with sufficient evidence to improve exercise performance in specific scenarios. Despite this, improved exercise performance with nitrate intake is not a universal finding among studies. Importantly, while nitrate appears to be effective in men, most studies conducted in women have not shown performance improvements with its supplementation. Although a logical interpretation of this is that nitrate is not performance-enhancing for the female athlete, we believe it is important to recognize that the literature on nitrate supplementation and women is small and limited, and more research is needed before drawing definitive conclusions.  

Female representation in research on nitrate supplementation and exercise is severely lacking, with only eleven studies to date conducted exclusively with women, while almost 100 investigations have been performed with men. Of those studies with women, most (8/11) of these did not find an improvement in exercise performance with nitrate, although there are some data to the contrary. A closer look at the results of a recent systematic review and meta-analysis may explain why many of the studies in women showed no benefit from nitrate supplementation. This meta-analysis suggested that the performance-enhancing benefit from nitrate ingestion may not occur when there is no control for antibacterial mouthwash use (since this can eliminate important bacteria that converts the nitrate to nitrite); with acute doses ≤4.9 mmol or ≥15 mmol and chronic doses ≤4.9 mmol or ≥10 mmol; when nitrate is ingested <150 min before exercise; for exercises with duration ≤120 s or >600 s. Accordingly, all studies to date that have demonstrated a lack of a performance-enhancing effect of nitrate in women possess at least one of these characteristics that may potentially compromise benefits from nitrate supplementation. Additionally, several of the nitrate studies in women did not control for the menstrual cycle phase and/or did not consider the use of oral contraceptives. This is important given that menstrual cycle phase and oral contraceptive use may influence exercise performance and the response to nitrate supplementation. 

Our recently published article in the Translational Journal of the American College of Sports Medicine aimed to highlight this discrepancy in the literature, namely that there is currently insufficient evidence to draw strong conclusions about the efficacy of nitrate supplementation for female athletes. There is a clear need for well-designed studies to determine whether women can benefit or not from this dietary supplement. This is especially important at a time when the number of female athletes at the Olympic Games is equal to that of male athletes and given the fact that even the smallest performance gains can make the difference between winning gold and failing to achieve the podium. To help researchers interested in this field, we have provided suggestions for studies investigating the effectiveness of dietary nitrate in female performance:  

1. Use a placebo-controlled, crossover, double-blind, and randomized study designs, due to the short duration of nitrate supplementation and its short washout period.  

2. To increase performance-enhancing effects (as based upon studies using predominantly males), studies should employ a 5-9.9 mmol dose of nitrate, using beetroot juice as a vehicle, ingested ≥150 min prior exercise lasting 120-600 s (e.g.: 4-km cycling time-trial, 1500 m and 3000 m running time-trial and 2000 m rowing) and avoid antibacterial mouthwash. 

3. Compare monophasic oral contraceptives users and a men-only group to determine if inherent physiological differences may lead to distinct performance responses to nitrate supplementation between women and men.  

4. Consider whether menstrual cycle phase alters the response to nitrate supplementation through comparisons of the effects observed between two or more phases.  

Women seeking to gain a competitive advantage from nitrate: 

We suggest that female athletes consult with a registered dietitian to determine the need for nitrate supplementation. If the decision to trial nitrate is taken, we suggest that female athletes rigorously and systematically test nitrate supplementation in, preferably in repeated competition simulations and compare it to their performance without nitrate, to verify if this strategy can enhance exercise performance and does not lead to side effects (e.g., mild gastrointestinal problems). If dietary nitrate proves to be consistently effective in improving performance during simulations and side effects are not observed, the athlete could consider its use in competition.   

For more detailed recommendations and explanations about the topic, please read the paper “Directions for Future Studies to Determine Dietary Nitrate Efficacy in Female Athletes." 

Arthur Carvalho, B.Sc., is a master’s student at the Faculty of Medicine of the University of São Paulo and a member of the Applied Physiology and Nutrition Research Group at the University of São Paulo, where he researches sex differences in exercise performance response to inorganic nitrate supplementation. 

Breno Duarte, MSc, is a Ph.D student at the Faculty of Medicine of the University of São Paulo and a member of the Applied Physiology and Nutrition Research Group at the University of São Paulo, where he researches physiological and performance responses to different sources of dietary nitrate supplementation. 

Bryan Saunders, Ph.D., is a researcher and lecturer in sport and exercise science at the Faculty of Medicine of the University of São Paulo, Brazil and a senior member of the Applied Physiology and Nutrition Research Group at the University of São Paulo. His main areas of research include nutritional supplementation to improve exercise performance, determination of the mechanisms through which these supplements act and what factors might moderate these effects. Bryan has applied sport science experience having provided performance analysis and physiology support to several UK-based football teams, has worked with elite cycling in Brazil and was previously a member of the São Paulo Cycling Federation. He currently serves on the editorial board of Frontiers in Nutrition and the Translational Journal of the American College of Sports Medicine. 

It is well established that regular physical activity is beneficial for the human body and mind. Many studies have outlined the effects of aerobic exercise and resistance training for longevity and optimization of the health span. There are well-established guidelines for physical activity, such as Physical Activity Guidelines for Americans by the U.S. Department of Health and Human Services. Unfortunately, only 24.2% of the American adult population meet the daily and weekly requirements for both aerobic and muscular-strengthening activity. 

Patients traditionally are asked to turn to their primary care physicians or other members of their health care team for guidance on how to best implement these physical activity recommendations. It is well established that physicians who are more physically active themselves are more likely to discuss exercise with their patients. However, is there a difference in recommendation between those physicians with general primary care training vs. those with specialty training in sports medicine? 

Our study, published in the November issue of Current Sports Medicine Reports, sought to answer this question by asking 649 participants about their personal exercise habits and counseling practices for their patients. We specifically compared primary care physicians with those who had received one extra year of specialty training in sports medicine; 72% of the respondents had previously or were currently completing a sports medicine fellowship training program. We found that those with sports medicine training were more likely to personally meet the physical activity guidelines than those without. 

A thought-provoking conclusion from the study was that physicians with more sports medicine training felt a personal obligation to meet the physical activity guidelines themselves. Additionally, almost a quarter of our study population felt uncomfortable counseling patients on their physical activity or exercise habits if they didn’t meet the guidelines themselves. 

Interestingly, we found that many providers felt limited for implementation of Exercise is Medicine® (EIM) in their practice, whether because they themselves felt inadequately trained in the subject or due to lack of resources. Therefore, we believe that the addition of more education on physical activity, such as EIM, and the implementation of such practices would benefit all levels of medical training. Hopefully, this additional training will help medical professionals combat the epidemic of decreased physical activity across the globe. A complimentary approach would be for physicians to directly work with exercise professionals, who can provide support and guidance for patients related to developing and maintaining a physically active lifestyle. The American College of Sports Medicine® has been a leader in providing resources, training, and certification programs for exercise professionals. 

Tyler Slayman, M.D., is a family medicine and primary care sports medicine physician at the University of Iowa Hospitals and Clinics and member of ACSM. As a marathoner himself, he serves as the director of the Endurance Athlete Program at UI Sports Medicine in Iowa City, Iowa. 

Viewpoints presented in ACSM Bulletin commentaries reflect opinions of the authors and do not necessarily represent positions or policies of ACSM. Active Voice 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. 

An internet search of “anti-obesity medications (AOMs)” will land over 63+ million hits in under a second. The surge in the popularity of AOMs is fostered by various media outlets (news, social, marketing, research) adding to increased patient demand. Trilliant Health/STAT reported that in 2022, ~3.6 million Americans were taking an AOM and estimate that this will increase by 35% by the end of 2023. 

After spending a combined 50+ years researching and translating lifestyle recommendations into obesity practice, we weren’t surprised when the public appetite for “Ozempic-like” medications exploded. Putting the costs, celebrity endorsements, and supply chain issues aside, let’s break it down, talk data and what this means for the physical activity profession. 

You may hear these therapies referred to by several different names — second- or third-generation AOMs, incretin-based hormone agonists, or nutrition-stimulated hormone-based therapies (NuSHs). But these agents are not all “Ozempic^®,” as people regularly refer to them. This likely happened because semaglutide was the first of these new agents that took the diabetes (Ozempic^®) and obesity (Wagovy ) worlds by storm. With FDA approval for weight loss in 2021, semaglutide 2.4 m.g. demonstrated over double the weight loss compared to previous medications. The STEP-3 trial boasted a weight reduction after 68 weeks of -16.0% compared to -5.7% with lifestyle only, and semaglutide resulted in 86.6% achieving a clinically meaningful weight loss of >5%. 

While the impact of these medications for weight reduction brings new excitement, the base mechanism of action is not new. In fact, glucagon-like peptide-1 (GLP-1), has been around for years, there are several positive clinical trials, and numerous trials are underway to continue exploring the safety and effectiveness of these agents. 

Next up and under FDA review for weight loss is tirzepatide, which is a dual agonist (GLP-1/GIP) that has demonstrated ~20% weight loss after 72 weeks. More agents are in the pipeline, with STAT reporting ~70 promising single, dual, and triple NuSHs and other therapies in clinical testing and development. 

It is hard to ignore the impact of these agents for weight loss compared to prominent behavioral lifestyle interventions like Look AHEAD and the Diabetes Prevention Program which have demonstrated a 5-10% average reduction in weight at one year. Yet, the benefits of the medications aren’t just about the number on the scale. Already mentioned was their impact in diabetes care, and recent pre-published evidence from the SELECT trial demonstrates a positive influence on cardiovascular health. 

We are not denying that lifestyle interventions, which include physical activity, can be effective for weight loss. However, there are still challenges that we must recognize. For example, not all individuals respond to lifestyle interventions, there is variability in response, and for the people that do respond, long-term maintenance of weight loss and prevention of weigh recurrence remains difficult. 

How do we move forward in this rapidly changing landscape that includes these powerful new therapeutic agents for weight loss? It begins by being honest about challenges and opportunities for physical activity professionals. 

The Challenges:

On these agents, patients: 

• Will lose significant weight without engaging in activity, 

• Will improve many health parameters without engaging in activity, and 

• May not see the value of activity specifically for weight loss. 

Despite these challenges, this may open the door for new physical activity opportunities. 

The Opportunities:

We can now: 

• Pivot from doses and intensities of physical activity for weight loss and prescribe based on improving health in patients using AOMs, 

• Target physical activity for the independent health benefits not realized with weight loss alone, and 

• Support patients on their holistic weight loss journey as a part of an integrated team of healthcare professionals. 

This is a redirect for many of us who realize the powerful benefits of physical activity. We must step away from positioning it as “physical activity vs. medication.” This type of thinking puts the method first rather than the patient. 

It is important for exercise professionals to recognize that excess weight and adiposity are due to the complex collision of biology, environment, and behavior. Obesity is not from an absence of willpower; thus, the basic premise to eat less and move more is difficult for many patients, and this may partially explain the variability in weight loss response. These medications help patients gain better control over their eating behaviors; however, they don’t magically improve physical activity engagement. In fact, our group recently presented data at Obesity Week 2023 demonstrating that the majority of patients taking these medications don’t initiate physical activity, and of those who do, most are not engaging in levels consistent with public health guidelines. 

Just as obesity is a multifaceted and complex disease, our group is taking the position that approaches to obesity care in this new age cannot be one size fits all — and this includes exercise prescriptions. We are using a bio-behavioral approach that prioritizes patient and clinician perspectives and biological responses to develop programming that may impact clinical implementation and guidelines. It may not be enough to just assume that the same physical activity and lifestyle approaches layered onto AOM therapies will have the same impact as previously demonstrated. After all, our recent data indicates that the majority of patients already know and have been told repeatedly by health care professionals that it is “important that they exercise.” There are likely deeper behavioral factors that continue to keep these patients from engaging in physical activity. 

Exercise professionals must ensure that they are not contributing to the stigma that many patients taking AOMs report, which includes feeling like or being told that they are “taking the easy way out.” For physical activity counseling to be effective, it is going to require appropriately trained and certified exercise professionals that want to work with patients taking AOMs and clinicians prescribing these agents. 

The profession has embraced physical activity as a complement to treatment for other chronic conditions, such as with cardiac rehabilitation. Now that AOMs provide effective medical treatment for obesity, it is time to embrace this opportunity as the next frontier in integrated patient care. 

Learn more from Drs. Rogers and Jakicic, along with their board-certified obesity clinician colleagues, at the IDEA & ACSM Health and Fitness Summit and at ACSM's Annual Meeting. 

Related CEC Courses: 
Rethinking Obesity Treatment with Fitness Pros (1 CEC)
Training the Adult with Obesity (3 CECs)

Dr. Renee J. Rogers, Ph.D., FACSM, is a senior scientist at the University of Kansas Medical Center and also works as an independent healthy lifestyle consultant and strategist. She chairs ACSM’s Strategic Health Initiative on Behavioral Strategies and Summit Program Committees. Dr. Rogers is an expert in bio-behavioral intervention design with a focus on relevant engagement approaches that blends her 20+ years of experience working in exercise physiology, behavior change, and weight management. 

Dr. John M. Jakicic, Ph.D., FACSM, is a professor of internal medicine in the Division of Physical Activity and Weight Management at the University of Kansas Medical Center. He is the chair of the ACSM’s Strategic Health Initiative on Obesity. Dr. Jakicic is an internationally recognized expert on body weight regulation and obesity treatment, with a particular expertise on the role of physical activity, and he has authored or co-authored over 300 peer-reviewed papers and book chapters.