Athletic Heart

Electrocardiogram Interpretation of the Athletic Heart:
Examples and Resources

by Elizabeth H. Dineen, DO, Heather Shenkman, MD, Gerald Bourne, MD and Victor Froelicher MD on behalf of the CA ACC Exercise Health & Sports Cardiology Committee.
For questions, contact us at

The American College of Cardiology’s California Chapter has established a Exercise Health & Sports Cardiology Committee in response to the growing need for evidence-based, standardized, comprehensive care for athletes. The committee aims to serve as a resource for consultative cardiovascular assessment of highly active individuals as well as a home for educational tools to aid in their assessment and management.

The present document will provide a succinct overview of the interpretation of the electrocardiogram (ECG) in the athletic population by providing select resources for a more comprehensive understanding of ECG changes occurring in athletes, supported by a few examples of abnormal findings.

This document does not serve to support or refute the case for pre-participation screening with an ECG, but rather as a resource to help those providers whenever they are faced with analyzing an athlete’s ECG, including team physicians, family medicine, sports medicine, cardiology, athletic trainers and others caring for athletic individuals.

1. ECGs provided in this document with brief description. ECGs obtained from Dr. Vic Froelicher.
2. “International recommendations for ECG in the athlete” provides tables and figures that clearly delineate:

Figure 1: Normal and Abnormal ECG Findings [PDF]
Table 1: Definitions of ECG Findings [PDF]
Table 2: Evaluation Suggested in the Setting of these ECG Findings [PDF]

Preparticipation Evaluation of the Athlete Heart: Questionnaire and Resources

Introduction to Questionnaire and Videos for the Athlete


     Why should you be concerned with answering these scary questions? Sure, heart problems and their complications including death are rare in young athletes. But what if the causes of these conditions and their complications were known and we knew their warning signs? Your parents, relatives and coaches would like you to be able to play sports safely. Modern medicine has made tools available for screening and treating heart conditions so why not take advantage of them? The first step in doing so is to watch these videos and answer these questions as best you can. Studies have shown us that they can be clues for recognizing the first signs of heart conditions. Your answers to these questions will be summarized for you to take to your annual screening for participation in organized sports with some suggestions for your doctor or organization to consider prior to sports participation. Even if you don’t have any of these symptoms now, you now know that if they ever occur they should be reported. Please share this resource with your teammates.

      Athlete Cardiovascular Risk Video Questionnaire

      Print out this form and watch the videos before entering your answer
      Videos are courtesy of the University of Texas Southwestern Medical Center (Dr. Benjamin Levine).

      1. Have you ever had discomfort, pain, tightness, or pressure in your chest during exercise?

      Watch Video, then check appropriate response on printed questionnaire. 

      2. Have you ever passed out or nearly passed out DURING exercise?

      Watch Video, then check appropriate response on printed questionnaire.

      3. Do you ever get so out of breath that you can’t continue to exercise even though your peers aren’t tired yet?

      Watch Video, then check appropriate response on printed questionnaire.

      4. Have you ever felt like your heart was racing, fluttering, or beating abnormally?

      Watch Video, then check appropriate response on printed questionnaire.

      5. Have you ever seen a doctor for a heart problem before?

      Check appropriate response on printed questionnaire.

      6. Has a doctor ever ordered testing for your heart, such as an EKG/ECG, x-ray, Echocardiogram, MRI or an exercise stress test?

      Check appropriate response on printed questionnaire.

      7. Has a doctor ever told you not to play sports before?

      Check appropriate response on printed questionnaire.

      8. Have you ever had an unexplained seizure?

      Check appropriate response on printed questionnaire.

      9. Do you take any performance supplements or energy drinks?

      Check appropriate response on printed questionnaire.

      Athlete COVID-19 Risk Questionnaire

      Since we are in a Pandemic, your Pre Participation exam ( PPE) must include questions regarding whether you have had COVID-19 or been exposed. The SARS-Coronavirus-2 (COVID-19) infection can cause damage to your heart (myopericarditis) even if you’ve only had minor exposure and not had any complaints or symptoms. Screening for active or prior infection, with appropriate work up could prevent life threatening consequences during or after physical activity. Please complete this questionnaire and give it to your Doctor, coach or trainer.

      Print out this form and enter your answer

      Current Recommendations for Cardiac Evaluation during the Covid-19 Pandemic

      There is understandable concern regarding intensifying cardiac evaluation and revising exercise recommendations during this pandemic because of the cardiac complications noted in severe cases of Covid-19. This remains a concern even though severe cases of Covid-19 are rarely seen in younger individuals since cardiac complications can occur months after even mild or asymptomatic cases. Recommendations are empirical and must be dynamic as knowledge grows and testing techniques improve. The latest recommendation (October 2020) was commissioned by the ACC Council on Sports Cardiology who chose America’s most active and experienced Sports Cardiologists and Sports Medicine specialists with cardiology knowledge to develop the document. The recommendation has been published in a peer reviewed journal and is available as a ACC webex video. The recommendations are specific for High School athletes (Figure 1), College and Professional athletes (Adults, Figure 2) and Master athletes (Figure 3). The experts also recommended adapted criteria for Myocarditis (Table 1). They presented specific cautions regarding the use of Magnetic Resonance Imaging (MRI) until pathological changes can be differentiated from those due to exercise training. The risk level of symptoms is provided in Table 2.. As you will see, these experts have observed that cardiovascular consequences of Covid-19 are relatively mild and so when compared to initial recommendations at the beginning of the pandemic, they have lessened indications for cardiac testing prior to return to play.

      It is assumed that the sport and exercise are performed consistent with current physical distancing, appropriate hygienic measures and face mask guidelines. Note that routine testing for the virus using a resting ECG looking for the repolarization changes associated with myopericarditis are not included at this time. Age and severity of illness have been emphasized and should be taken into account when considering cardiovascular diagnostics. Note also that at this time the benefits of exercise far outweigh the risk of exercise-induced cardio-pulmonary damage in the young. Our committee promulgates these recommendations with the caveat that they may be superseded by other guidelines as new knowledge comes available.

      The pathology (fibrosis, inflammation and thrombosis) of damage to the heart and lungs has been demonstrated but their time course and severity are uncertain but appear to be mild in athletes. Also it is not certain to what degree exercise training can exacerbate the damage caused by the pathogen but the experience so far is that this appears to be minor as well.

      Suggestions for the Physician Performing the PPE

      Pre Participation Exam (PPE) Screening

      The PPE is widely advocated for all youth athletes engaged in competitive sports. This year, in order to screen for the possible consequences of COVID-19, all athletes should undergo a PPE that assesses current or past symptoms of the SARS-Coronavirus-2. Testing to exclude significant cardiopulmonary disease should be based on the algorithms provided below. Most organizations suggest individual screening by a qualified clinician ( or trainer ) who has an available cardiology ( or sports medicine ) consultant. Mass screenings would require extreme precautionary measures in order to maintain physical distancing. All screening should follow guidelines outlined by the California Department of Public Health, including cleaning of equipment (eg., ECG machines and wires to electrodes). Among athletes with definite or possible prior infection, the use of adjunctive testing including electrocardiography, cardiac biomarkers, non-invasive imaging, and exercise testing represent appropriate options for more definitive risk stratification as outlined in the presented algorithms. History of new cardiac symptoms is extremely important and may be difficult to distinguish from deconditioning which can be due to sheltering in place. Importantly, myopericarditis related to COVID-19 should be considered in athletes with a history of new onset chest pain/pressure (even in the absence of fever and respiratory symptoms), palpitations, exercise intolerance, and/or resting or exercise related excessive tachycardia. Comprehensive clinical evaluation, regardless of ECG findings, is indicated in athletes with new onset cardiovascular symptoms or exercise intolerance. COVID-19 affected myocardial tissue can promote cardiac arrhythmias, and a major aim of the PPE is to identify those at risk for cardiac arrhythmias. At Stanford, an inexpensive ECG patch that can be automatically interpreted for PVC burden in clinic is being evaluated for this purpose in athletes recuperating from COVID-19.

      Table 1. Adapted Criteria for Myocarditis

      Myocarditis (Probable Acute Myocarditis With Both of the Following Criteria)

      1. Clinical syndrome, including acute heart failure, angina-type chest pain, or known myopericarditis of less than 3 months’ duration.

      2. Otherwise unexplained increase in serum troponin levels, ECG repolarization abnormalities, arrhythmias or high-grade atrioventricular block, abnormal ventricular wall motion, or pericardial effusion. Additional cardiac MRI findings that suggest myocarditis.

      Sports Eligibility Myocarditis Recommendations

      1. Before returning to sports, athletes diagnosed with a clinical syndrome consistent with myocarditis should undergo a resting echocardiogram, ambulatory ECG monitoring, and an exercise test no less than 3 to 6 mo after the illness.

      2. It is reasonable that athletes can resume training and/or competition if all of the following criteria are met:

          A. Ventricular systolic function has normalized.
          B. Serum markers of myocardial injury, heart failure, and inflammation have returned to normal levels.
          C. Clinically relevant arrhythmias are absent.

      Table 2. Risk levels of Symptoms

      1. Mild Symptoms

      include anosmia, ageusia, headache, mild fatigue, mild upper respiratory tract illness, and mild gastrointestinal illness;

      2. Moderate Symptoms

      include persistent fever, chills, myalgias, lethargy, dyspnea, and chest tightness;

      3. Severe Symptoms

      include dyspnea, exercise intolerance, chest tightness, dizziness, syncope, and palpitations which often require hospitalization.

      Figure 1. Coronavirus Disease 2019 (COVID-19) Return-to-Play Algorithm for Athletes in Competitive High School Sports

      This is the currently recommended algorithm (Oct 2020) for high school athletes with confirmed COVID-19. Note that among the cardiovascular (CV) symptoms, syncope of unclear cause identifies individuals who definitely require advanced CV testing, including cardiac magnetic resonance (CMR) imaging, exercise testing, and ambulatory ECG monitoring. Typical initial testing is obtained via a nasopharyngeal swab and polymerase chain assay for conserved regions of severe acute respiratory syndrome coronavirus–2 RNA. Multisystem inflammatory syndrome in children (MIS-C) involves fever, rash, abdominal pain, vomiting, diarrhea, lethargy, and conjunctivitis, possibly developing weeks after infection. The guidelines for RTP after myocarditis is indicated in Table 1.


      CDC – US Centers for Disease Control and Prevention; ECG, 12-lead ECG/EKG; echo, echocardiogram; hs-cTn, high-sensitivity cardiac troponin-I; RTP, return to play.

      Figure 2. Coronavirus Disease 2019 (COVID-19) Return-to-Play Algorithm for Collegiate and Professional Athletes in Competitive Sports

      This is the currently recommended algorithm (Oct 2020) for all college and professional athletes with confirmed COVID-19. Note that among the cardiovascular (CV) symptoms, syncope of unclear cause identifies individuals who definitely require advanced CV testing, including CMR imaging, exercise testing, and extended rhythm monitoring. (see comments and legend for Table 1).

      Figure 3. Coronavirus Disease 2019 (COVID-19) Return-to-Play Algorithm for Recreational Masters Athletes

      This is the currently recommended algorithm (Oct 2020) for all athletes at the masters level with confirmed COVID-19. Cardiovascular disease (CVD) risk factors include hypertension, coronary artery disease, atrial fibrillation, and diabetes. (see comments and legend for Table 1).

      Resumption of Institutional Sports

      Multiple organizations have produced guidelines for the resumption of sport. During this time, we would like to emphasize the importance of trainers and coaches frequently communicating with athletes about symptoms and involving the medical staff when necessary. Additionally, preparedness with a rehearsed strategy, including an AED use, for potential cardiac events should be enacted even before training commences. Most of the information regarding the prevalence and severity of cardio-pulmonary sequelae in athletes who have survived COVID-19 is limited but our experience is growing rapidly.

      Cardiopulmonary Exercise Testing: Indications, Interpretation & Cases

      Exercise Health & Sports Cardiology Committee

      The American College of Cardiology’s California Chapter has established an Exercise Health and Sports Cardiology Committee in response to the growing need for evidence-based, standardized, comprehensive care for athletes. The committee aims to serve as a resource for consultative cardiovascular assessment of highly active individuals as well as a home for educational tools to aid in their assessment and management.

      The Cardiopulmonary Exercise Test


      Physical activity requires the integrated performance of cardiovascular, pulmonary, metabolic, and neuromuscular systems. The Cardiopulmonary Exercise Test (CPET or CPX) evaluates the concerted response of these systems during exercise and provides an assessment of each component required for exercise performance. In contrast to standard exercise test modalities, the defining element of CPET is the continuous measurement of ventilation and gas exchange.

      The relationship between oxygen consumption and carbon dioxide production and a vast array of non-invasive physiological parameters are used to determine the function of each component of physical exertion. From rest, through moderate exercise, to exhaustion, CPET enables an evaluation of overall capacity of the subject and the physiologic integrity of each system from ventilation, to circulatory transport, to tissue uptake. Although the significance of disturbances in the relationships between physiologic systems measured during CPET may be initially daunting, the utility and indications for this test are important and easy to understand.

      Cardiopulmonary fitness is determined by measuring oxygen uptake (V̇O) at maximal exercise, while the ventilatory (anaerobic) threshold (VT) occurs at a submaximal point during exercise when pulmonary ventilation increases disproportionately to oxygen uptake. Cardiovascular limitations are exemplified by low values for peak V̇O and ventilatory threshold. The ratio of oxygen uptake to work rate is reduced due to an impaired ability of the cardiopulmonary system to provide oxygen to the working muscles. A low stroke volume may be reflected by a low peak V̇O per heart beat (O pulse). Pulmonary limitations that may result in a reduced V̇O are revealed by an abnormal breathing reserve, oxygen desaturation, CO retention, or abnormal expiratory flow rate. Peripheral myopathy is suggested by a low peak V̇O , with an elevated minute ventilation to V̇O ratio and a high cardiac output to V̇O slope. Further discrimination of the cause of exercise intolerance can be determined by evaluating the relationships between additional variables. Endurance athletes commonly will have findings on CPET that may be considered abnormal in the sedentary population. These athletes may have higher peak V̇O , higher anaerobic threshold, a high O pulse reflecting a higher stroke volume and a maximum exercise ventilation that nearly matches the maximum voluntary ventilation, such that the breathing reserve is nearly zero given their exceptionally high cardiovascular capacity.


      Dyspnea of unknown etiology

      CPET can help differentiate between pulmonary, cardiac, neurologic, muscular and psychological basis of dyspnea that limits exercise performance.

      Diagnosis and assessment of the severity of organ dysfunction, relative compensatory contributions of other organ systems, prognosis, sequential monitoring in the following disease processes.


      Heart Failure with reduced ejection fraction
      Heart Failure with preserved ejection fraction
      Valvular Heart Disease
      Hypertrophic Cardiomyopathy
      Congenital Heart Disease: Persons with CHD often have abnormal recognition of DOE
      Coronary Artery Disease.


      Pulmonary Artery Hypertension
      Secondary Pulmonary Artery Hypertension
      Chronic Obstructive Pulmonary Disease
      Interstitial Lung Disease


      Mitochondrial Myopathy
      Neuromuscular Disease
      Chronic Fatigue/ Post Exertional Malaise

      Assessment of Surgical Risk

      CPET responses have been increasingly applied to stratify risk as part of pre-surgical assessment. For example, peak V̇O strongly predicts risk for surgical complications, length of hospital stay, and ability to return to work across a wide spectrum of surgical interventions.

      Development of Cardiac or Pulmonary Rehabilitation exercise prescriptions and guidelines

      The foundation of an appropriate exercise prescription in a patient with cardiovascular or pulmonary disease is the exercise test, and because of its superior precision, the CPET provides the most accurate method to develop an individualized exercise prescription.

      Assessment of safety and metrics for an exercise training program

      The CPET provides a wealth of information on safety, rhythm abnormalities, ischemic responses, and symptoms that are important in developing a safe and appropriate exercise prescription.

      Assessment of cardiorespiratory fitness and subsequent response to a training program or interventions in healthy individuals, athletes or those with underlying cardiovascular disease (as listed above)

      The CPET provides an accurate metric to quantify changes in fitness in response to exercise training and other interventions (eg. drug, surgical or device) among both healthy individuals and those with cardiovascular disease.

      How to Perform a Cardiopulmonary Exercise Test

      Equipment and Staff

      CPET test administration requires specific equipment and personnel in order to generate accurate and reliable data.


      Ergometer (cycle, treadmill, rowing simulator, etc)
      Gas exchange mask/mouthpiece
      Metabolic cart consisting of gas analyzers, expiratory gas flow and volume, and software
      Continuous electrocardiogram
      Blood pressure measurement device


      Exercise physiologist to set up the exercise protocol, prepare/calibrate equipment and possibly monitor during the test
      Medical assistant or nurse to monitor during the test
      Qualified medical professional for interpretation of the test

      Many patients can be tested on a cycle ergometer or treadmill, based on comfort level and lab availability. If testing athletes, the type and intensity of the test protocol should be matched to their sport (ex: having a sprinter perform sprints on a treadmill or a rower using the rowing ergometer) which will provide more useful test results. Cycle tests are logistically easier for monitoring blood pressure and generate electrocardiogram tracings with fewer artifacts and unstable baselines.

      The exercise protocol will vary depending on the interview conducted by the ordering provider. Common exercise protocols include the step protocol (ex: Bruce-type protocol), with a step-wise or incremental increase in work rate over time, or a ramp protocol with a continuous increase in work rate over time. The exercise test should be individualized by the exercise physiologist or medical provider administering the test with a target test time between 8-12 minutes.


      Key Metrics

      Heart rate, blood pressure, and electrocardiographic responses to exercise should be evaluated in a similar fashion as a routine exercise test
      Ventilation and Gas Exchange: Measured throughout exercise
      Maximum V̇O₂ : This is the aerobic capacity or total body oxygen uptake verified by achieving a heart rate within 10 bpm of the age-predicted HRmax, a lack of change in the V̇O over two consecutive work rates, and/or a respiratory exchange ratio above 1.10 (presumably reflecting a lactate accumulation above 70-80 mg/dl). If these criteria cannot be met, the oxygen uptake at maximally tolerated exercise is referred to as peak V̇O . V̇O is often a metric that is tracked over time to monitor treatment or interventions as well as to monitor disease progression or prognosis.
      V̇CO₂: Carbon dioxide elimination measured throughout the test.
      Lactate Threshold V̇O₂  Anaerobic Threshold ( AT )  Ventilatory Threshold ( VT ): V̇O above which lactate accumulates in the blood. This may be a useful marker of an individual’s cardiorespiratory fitness and endurance. Often referred to as anaerobic threshold or ventilatory threshold. Can be determined by ventilatory analogs of lactate accumulation such as V̇O vs V̇CO and V̇E vs V̇O graphs. 
      Respiratory exchange ratio (RER): The ratio of CO produced to oxygen consumed (V̇CO/V̇O). A marker of fuel utilization (0.70 ≈ fat utilization and ≥1.0 ≈ carbohydrate utilization). Also a reflection of the degree of physiologic effort (≥1.10 associated with maximal effort)
      Oxygen Pulse (V̇O₂ /HR): Will increase at the beginning of exercise largely due to the increase in stroke volume and then will reach a plateau near the end of exercise. If this plateau is reached sooner than expected, it can be due to impaired oxygen extraction or impaired stroke volume (due to CAD or left ventricular dysfunction).
      Pulmonary Ventilation (V̇E): Volume of air exhaled per unit time. Generally not a limiting factor unless there is a low breathing capacity or a disease state that impairs air flow.
      Change in V̇O₂ /change in work rate: This generally has a linear relationship of 10 mL/min of oxygen uptake for every 1 Watt increase in work rate. This relationship may change in illnesses such as cardiovascular diseases where oxygen uptake may be decreased compared to change in work rate.
      Heart rate recovery: Reflection of vagal reactivation. Slow heart rate recovery associated with higher adverse outcomes. Often expressed as 1-minute post exercise (HRR1) or 2-minutes post exercise (HRR2). HRR1 <12 beats/min or HRR2 <22 beats/min associated with higher risk.
      V̇E/V̇CO₂: Can be expressed as a ratio (at a point in time during exercise) or as the slope of the change during exercise. Reflects ventilatory efficiency, ie. the ventilatory requirement to eliminate a given amount of CO, and is a strong prognostic marker.
      Oxygen uptake efficiency slope (OUES): The relation between the change in oxygen uptake during exercise and the log of the change in ventilation. The OUES is another measure of ventilatory inefficiency, and is a strong predictor of prognosis in patients with heart disease.
      Perceived exertion: A reflection of the degree of the individual’s physical effort. Often expressed using a 6-20 scale, with 6 representing a resting state and 20 representing maximal effort.

      Cardiopulmonary Exercise Test Cases


      The patient is a 60 year old sedentary Caucasian male outpatient 71 inches tall, weighing 180 lbs. He is currently not smoking but has 23 pack years of smoking (1 pack/day for 23 years). The patient’s weight is normal (BMI=25). A history of abnormal lipids was reported (high TC, LDL, low HDL). The patient also has a history of high blood pressure. He over the past 6 months has noted increasing shortness of breath with exertion.

      Reason for Referral

      Evaluation of increasing shortness of breath with regular daily activities.

      Past Medical History

      There is a history of “mildly reduced ventricular function”, diagnosed approximately 6 years ago, although no imaging results are available. He reports infrequent “skipped beats”. No other history of non-cardiac or other medical problems are noted. Current medications include an ACE inhibitor, statin, and diuretic.

      CPX Test Results


      • ECG: Normal sinus rhythm and left bundle branch block.
      • Pulmonary Function: Forced vital capacity is 3.50 L (79% of expected) and the FEV1/FVC is 50% (Normal > 75%).
      • Heart rate: 71
      • Blood pressure: 112/68


      • Severely impaired exercise tolerance
      • Early dyspnea during exercise and daily activities, ventilatory inefficiency suggest impaired cardiac output
      • Higher than normal risk for age indicated by severely impaired peak V̇O₂ , heart rate recovery, and indices of ventilatory inefficiency

      Key Items

      • Peak RER and perceived exertion suggest maximal effort
      • Limiting symptom was dyspnea; no chest discomfort reported
      • Severely impaired exercise tolerance (40.4% of age-predicted peak V̇O₂ )
      • Exercise ECG not analyzable due to LBBB; infrequent PVCs occurred
      • Normal heart rate and blood pressure response; impaired heart rate recovery at 1 and 2 min post exercise
      • Ventilatory threshold occurred at low V̇O₂ (7.7 ml/kg/min) but normal percentage of peak
      • Normal breathing reserve; high V̇E/V̇CO₂ slope and low OUES suggest ventilatory inefficiency
      • Low peak O₂ pulse; plateau beginning ≈50% of peak
      • Abnormal resting PFTs suggest airflow limitation and possible pulmonary contribution to exercise intolerance


      • Myers J, Arena R, Cahalin L, Labate V, Guazzi M. Cardiopulmonary exercise testing in heart failure. Current Problems in Cardiology 40:322-372, 2015.
      • Malhotra R, Bakken K, D’Elia E, Lewis GD. Cardiopulmonary exercise testing in heart failure. JACC Heart Fail 4:607-16, 2016.
      • Balady GJ, Arena R, Seitsema K, Myers J, Coke L, Fletcher GF, Forman D, Franklin B, Guazzi M, Gulati M, Keteyian S, Lavie CJ, Macko R, Mancini D, Milani RV. A Clinician’s Guide to Cardiopulmonary Exercise Testing. A Scientific Statement from the American Heart Association. Circulation 122:191-225, 2010.

      Case Study: Coronary Artery Disease


      The patient is a 68 year old sedentary Caucasian male outpatient 65 inches tall, weighing 160 lbs. The patient is currently not smoking but has a 50 pack year history of smoking (2 packs/day for 25 years). The patient is 10 lbs over the average appropriate body mass index (BMI=26.6) which qualifies as overweight. A history of abnormal lipids was reported (high TC, LDL, low HDL). The patient also has a history of high blood pressure.

      Reason for Referral

      Evaluation of chest pain

      Past Medical History

      The patient has the following symptoms: shortness of breath with regular daily activities and occasional mild chest discomfort. There is no other history of cardiac disease, cardiac events or dysrhythmias. No other history of non-cardiac or other medical problems are noted. Current medications include a beta blocker, ACE inhibitor, statin, and diuretic.

      CPX Test Results


      • ECG: Within normal limits
      • Pulmonary Function: Forced vital capacity 2.9 L (73% of expected) and the FEV1/FVC is 53% (Normal > 75%)
      • Heart rate: 76
      • Blood pressure: 146/78


      • Exercise intolerance attributable to high likelihood of CAD (ischemic ECG changes, chest pain, plateau of O₂ pulse)
      • Pulmonary involvement suggested by low FEV1, limited breathing reserve, elevated V̇E/V̇CO₂ slope and reduced OUES
      • CPET results suggest further evaluation for CAD is warranted.

      Key Items

      • Peak RER and perceived exertion suggest maximal effort
      • Impaired exercise tolerance (62% age-predicted peak V̇O₂ achieved)
      • Exercise ECG shows 2.0 mm downsloping ST depression; resolved by 2 min recovery; no arrhythmias observed
      • Chest discomfort (≈1 out of 4) at peak exercise resolved by 1 minute in recovery
      • Chronotropic incompetence; impaired heart rate recovery
      • Borderline breathing reserve; V̇E/V̇CO₂ slope and OUES suggest ventilatory inefficiency; normal O₂ sat
      • Flattening of O₂ pulse beyond ≈50% V̇O₂


      • Chaudhry S, Arena A, Hansen JE, Lewis GD, Myers J, Sperling LS, LaBudde BD, Wasserman K. The utility of cardiopulmonary exercise testing to detect and track early-stage ischemic heart disease. Mayo Clin Proc 85:928-932, 2010.
      • Balady GJ, Arena R, Seitsema K, Myers J, Coke L, Fletcher GF, Forman D, Franklin B, Guazzi M, Gulati M, Keteyian S, Lavie CJ, Macko R, Mancini D, Milani RV. A Clinician’s Guide to Cardiopulmonary Exercise Testing. A Scientific Statement from the American Heart Association. Circulation 122:191-225, 2010.
      • Chaudhry S, Arena R, Bhatt DL, Verma S, Kumar N. A practical clinical approach to utilize cardiopulmonary exercise testing in the evaluation and management of coronary artery disease: a primer for cardiologists. Curr Opin Cardiol 33:168-177, 2018.

      Case Study: Chronic Fatigue Syndrome (CFS) / Post-Exertional Malaise (PEM)

      History of Current Complaint

      Patient is a 52 yo female who reports weakness in arms and legs for the past 14 years. Over the past 4 years, she has experienced profound fatigue after mild activity that may last for days. She discontinued using her stationary cycle two years ago. She felt compelled to quit her job due to fatigue and weakness. When deeply fatigued, she has short-term memory deficits and a sensation she describes as “brain fog.”

      Reason for Referral

      Two-Day CPX (24-hour interval) to document functional capacity on Test-1 and Test-2; identify bio-markers consistent with CFS/PEM.

      Past Medical History

      Patient never smoked. No DM, HTN, hyperlipidemia, renal or pulmonary disorders. Muscle CK and inflammatory markers are negative. Normal echocardiogram. No previous exercise tests. Normal blood panel and Chem-7.
      CXR is normal.

      CPX Test Results


      • Normal pre- and post-exercise on both Test-1 and Test-2


      • Patient cycled to volitional exhaustion on a 10 Watt ramp protocol.

      PeakV̇O₂ :

      • Supra-normal peak V̇O₂ in both tests.

      Ventilatory threshold (V-AT):

      • Analog of lactate threshold (V-Slope method) was normal.


      • Patient achieved 88% age-predicted HRmax in both tests with normal ECG; no ectopy or dysrhythmia, normal BP response.


      • Ventilatory response was normal and nearly identical in both Test-1 and Test-2: slope V̇E/V̇CO2 = 27, PetCO₂ = 39-4

      Key CPX Variables

      • PeakV̇O₂ : reduced by 12% in Test-2
      • Maximal work rate: reduced by 14% in Test-2
      • Work@V-AT: reduced by 9.5% in Test-2
      • V̇O₂ per unit work: increased 8% in Test-2. The higher V̇O₂ /Watt in Test-2 reflects reduced mechanical efficiency, attributed by some clinicians to muscle micro-injury, and possibly uncoupling of oxidative phosphorylation due to mitochondrial dysfunction created by test-1 exercise. These changes are consistent with Post-Exercise Malaise (PEM), a principle correlate of CFS.



      Exercise is limited by muscular fatigue, greater in Test-2, associated with reduced peakV̇O , maximal work rate, work at V-AT, and an increased V̇O per unit work, consistent with PEM/CFS as described in the literature.

      Suggested Reading

      • Nelson M, Buckley JD, Thomson RL, Clark D, Kwiatek R, Davison K. Diagnostic sensitivity of 2-day cardiopulmonary exercise testing in myalgic encephalomyelitis / chronic fatigue syndrome. J Trans Med 2019;17:80-88.
      • Stevens S, Snell S, Stevens J, Keller B, Van Ness JM. Cardiopulmonary exercise test methodology for assessing exertion intolerance in myalgic encephalomyelitis / chronic fatigue syndrome. Frontiers in Pediatrics 2018;6:242.
      • Snell CR, Stevens SR, Davenport TE, Van Ness JM. Discriminative validity of metabolic and workload measurements for identifying people with chronic fatigue syndrome. Physical Therapy 2013;93(11):1484-1492.

      Case Study: Exercise Prescription and Training


      Patient is a 70 yo female who requests exercise evaluation and prescription in preparation for attempts to climb to base-camp on Mount Everest (17,500 feet) and Mount Kilimanjaro (19,341 feet). She denies chest discomfort when exercising.


      Assess peakV̇O , ventilatory anaerobic threshold (V-AT), and optimal target HR six months prior to climbing events to provide training guidelines ( TEST 1). Perform second CPX two weeks prior to the event to assess progress and status ( TEST 2).

      Past Medical History

      No HTN, hyperlipidemia, diabetes, pulmonary disease, cardiac disease. Never a smoker. BMI = 22.48. She is active and participates in Pilates and Zumba exercise classes.

      CPX Test Results

      10 Watts ramp cycle protocol.

      Other CPET Resources

      • A Practicum: Cardiopulmonary Exercise Testing and Interpretation. Includes didactic lectures, small group tutorials, and laboratory demonstrations with CPET. Usually, 3 practicums are held each year, next tentatively scheduled for October 8-10, 2020.
      • Textbook: Principles of Exercise Testing and Interpretation 5th Edition. Authors: Karlman Wasserman, James E. Hansen et al. Marco Guazzi, Francesco Bandera, Cemal Ozemek, David Systrom, Ross Arena.
      • Marco Guazzi, MD, PHD,a Francesco Bandera, MD, PHD,a Cemal Ozemek, PHD,b David Systrom, MD,c,d Ross Arena, PHDb, Cardiopulmonary exercise testing: what is its value? J Am Coll Cardiol. 2017 Sep, 70 (13) 1618-1636.
      • Guazzi M, Adams V, Conraads V, et al. EACPR/AHA Scientific Statement. Clinical recommendations for cardiopulmonary exercise testing data assessment in specific patient populations. Circulation. 2012 Oct;126(18):2261-2274. DOI: 10.1161/cir.0b013e31826fb946.