Killer Workouts - The Adult Athlete

Written By Ian Riddock

Case Presentation:

The death of Jim Fixx (JAMES F. FIXX DIES JOGGING; AUTHOR ON RUNNING WAS 52 - The New York Times) is probably the example most cited by our patients, but many of us athletes have either personally witnessed or been told of an athlete dropping dead in the middle of a race or event. Leading up to such an event, this author was interviewed by a news outlet in an effort to promote awareness and screening. Despite these efforts, there was a follow up interview the day after the race, discussing the ultimate tragedy - sudden cardiac death just after the finish line. How could this be?

While this article is generally focused on the cardiometabolic manifestations related to exercise, there are several examples of less common, but critically important congenital conditions that deserve to be at least mentioned when discussing exercise and the risk of sudden cardiac death. Particularly since exercise, to include weight lifting, is such an important and recommended component of heart healthy living. 

A thorough review of all causes of SCD related to exercise is beyond the scope of this article, but some notable examples are worth touching on. 

For example, getting deployed overseas is a great time to focus on health and fitness and come home shredded. Events such as deadlift competitions, however, can produce extremely high intrathoracic and arterial pressures (Aortic dissection type I in a weightlifter with hypertension: A case report). Acute aortic dissection (Aortic Dissection in a Healthy Male Athlete: A Unique Case with Comprehensive Literature Review) and death have been reported in weightlifters during such extreme activities. Such cases are rare, but appropriate screening and knowledge of family history may have prevented these tragic events. Intense isometric exercise is contraindicated (inadvisable) in individuals with predisposition for aortic aneurysm or aortic rupture.  

Flying Under the Radar

Ironically, some of the fittest people, despite a sometimes consuming attention to healthy lifestyle behaviors fail to screen themselves appropriately for the most lethal disease in our society. 


Healthy athletes often fall short on screening for heart disease due to a “healthy athlete bias” whereupon they and their clinicians place too much emphasis on what are called “modifiable risk factors.” These are risk factors one has control over such as diet, exercise and smoking. Disproportionately less emphasis is “non-modifiable risk factors” which are risk factors one has no control over, such as genetics. As we often like to say “you cannot pick your parents, nor run away from your genetics.” This bias negatively impacts the athlete, who tragically gets less attention from the healthcare system. 


Reinforcement of this bias is not hard to find. For instance, while watching a sporting event on television, one commercial from a local healthcare system contends that up to 80% of heart disease can be prevented through proper diet and lifestyle choices. It then cuts away to show healthy appearing people jogging on a trail and doing pushups. An athletic individual watching at home may resemble these actors and have the impression that they are somehow protected. 


The reality is nearly ¾ of young patients (Men < 55 and women < 65 years of age) presenting to the hospital with their first heart attack, would’ve never qualified for a statin based upon conventional risk calculators (Preventing myocardial infarction in the young adult in the first place: how do the national cholesterol education panel iii guidelines perform?). This demonstrates the difficulty in conventional screening calculators in the apparently healthy and particularly younger patient.




CardioAdvocate Checklist:

Know your family history. 

  • Having a first degree relative (including a son or daughter), particularly a sibling, with heart disease is one of the strongest risk factors for premature ASCVD.

  • Certain congenital conditions can be familial (passed down through genes)



Deep Dive

Jim Fixx was not exactly the healthiest of athletes at baseline. He was 35 when he took up running (The Jim Fixx Neurosis: Running Yourself to Death - The Washington Post). He had numerous risk factors, to include smoking 2 packs per day, being overweight at 220 lbs, a strong family history of premature coronary artery disease - his father suffered his first heart attack at age 35 and died after a second heart attack at age 43 (JAMES F. FIXX DIES JOGGING; AUTHOR ON RUNNING WAS 52 - The New York Times), high stress as editor of a magazine and 2 divorces.


Jim Fixx wrote a best-selling book about running. He was among other running authors of that era who encouraged readers to “listen to their bodies, instead of doctors” (​​10.1080/02701367.2002.10608990). But in yet another twist of irony, he did neither. He ran through his chest pain. Autopsy revealed severe obstructive 3-vessel coronary artery disease with 95%, 85% and 70% blockages as well as multiple infarcts in multiple stages of healing. 


While smoking certainly confounds the death of Jim Fixx, the death of an apparently healthy athlete is a perplexing and frightening event. But it is not new. Indeed, Pheidippides died shortly after running, well a marathon, from Marathon to Athens in 490 B.C. Today, Sudden Cardiac Death (SCD) during sports occurs in 5-6% in the general public. There is a 9:1 male to female ratio in those > 35 years age, considered the “older athlete” (Sudden Cardiac Death in the Older Athlete | Journal of the American College of Cardiology). Sudden cardiac death risk for runners has been reported as 0.8 to 2 per 100,000 marathon runners (Risk for sudden cardiac death associated with marathon running | Journal of the American College of Cardiology).  54% are over age 35. 57% are male (Sudden Cardiac Death in the Older Athlete | Journal of the American College of Cardiology). 


While that may not seem like a lot, when you consider there are approximately 20 million athletes (and growing) participating in foot races in the US annually, with a running craze that is attracting a more aging population, you are bound to hear about it in your community. For instance, a popular community race in Spokane, WA called “Bloomsday” brings about 45,000 runners participating in a 7.4 mile run. In 2018 there was 1 death near the finish line and reportedly 7 or 8 collapses that day. There was an aborted Sudden Cardiac Death in 2017 thanks to the quick action of nearby healthcare workers. This shocked the community and was well covered by the local news stations.

But Does Exercise TRIGGER the Heart Attack?

There is relatively sparse information on this question. There is evidence that suggests long term exercise is protective against atherosclerosis (Long-term Exercise and Atherogenic Activity of Blood Mononuclear Cells in Persons at Risk of Developing Ischemic Heart Disease | Cardiology | JAMA.)


However other data suggests exercise CAN trigger a heart attack (Triggering of Acute Myocardial Infarction by Heavy Physical Exertion -- Protection against Triggering by Regular Exertion | NEJM). But the above study suggests that the more sedentary an individual is, the more likely it is that HEAVY physical exertion will provoke an MI. Habitual and moderate to high intensity exercise appears to reduce this risk (Triggering of Sudden Death from Cardiac Causes by Vigorous Exertion | NEJM, Leisure-time physical activity and the risk of primary cardiac arrest).

What’s the Mechanism?

Not entirely clear. Possible mechanisms are sympathetic activity, ischemia, activation of hemostatic system, hemodynamic effects on vulnerable plaque, electrolyte and metabolic factors with prolonged exercise. Indeed, the length of the activity appears to be a factor. The majority of SCD occurs in the last ¼ of a marathon. There are more SCD events during marathons than ½ marathons.



So Then What’s the Deal with the Higher Coronary Artery Calcification in Athletes?

Progressive or premature coronary artery calcification has been associated with chronic intense exercise as well. It is unclear whether such athletes have the same risk as nonathletes with similar high CAC scores.


More to come on this.


So What’s the Verdict?

Yes, HEAVY exertion can kill you, but it’s rare and more likely to do so if you are not accustomed to exercise. The more you exercise, the less likely that HEAVY exertion will kill you. 


Exercise is medicine. Movement is medicine.


When tragedy strikes, it’s usually the “older” athlete (> 45 years of age) and usually due to coronary artery disease. Appropriate screening, particularly with Coronary Artery Calcium CT scans, can detect coronary artery disease in such patients. We have the tools to treat this. It’s not hard.

Can Too Much Exercise Cause Other Cardiac Issues in an Otherwise Healthy Athlete?

There can potentially be pathologic changes related to the ongoing effects from intense exercise. 

Exercise Dose

It’s debatable whether there exists a “J-shaped” curve when it comes to exercise intensity and volume. What this means is that as one begins to exercise, a small to intermediate amount of exercise intensity and volume offers protection, or an advantage over those who don’t, when it comes to death or cardiac death and other cardiac related problems. But as exercise intensity becomes more extreme, it may begin to negatively impact the risk for death, cardiac death or other bad cardiac problems. In other words, is there an appropriate “dose” of exercise that is ideal? Like Goldilocks. Not too little, not too much.


Based upon the Copenhagen Male Study, there appears to be a “dose-dependent” increase in lifespan with higher cardio fitness. Meaning, NO J-shaped curve (Midlife Cardiorespiratory Fitness and the Long-Term Risk of Mortality: 46 Years of Follow-Up).

Ian Riddock
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