Extreme Fatigue in Endurance Athletes

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I am a month away from my 79^th birthday. I do not exercise as long or as hard as I used to because of a hip fracture and replacement from a bicycle accident and because of my transcatheter aortic valve replacement (TAVR) which I discussed previously. (1)

But I spent the last two weeks on vacation at our lake house in Maine, where my favorite, and only, wife grew up. One day I got a little overenthusiastic given my age and health, and cycled 41.5 miles up 2,500 feet on the roads near the lake. I am slow, 12.1 miles per hour so I rode straight for three and a half hours. That was added on to 15 to 30 miles of cycling on each of the days before this bike ride. For two days after my long ride, I was absolutely exhausted. I had forgotten how severe the fatigue from too much exercise can be. This event reminded me of a rule:

Fatigue in endurance athletes is almost always due to overtraining.

I did not say “always”, but “almost always.” Sure, there can be other causes such as hypothyroidism, liver disease, viral infections, but if it is present at rest in an athlete or occurs with minimal exertion, it is usually simply “too-much-exercise” fatigue. This can occur from too much repeated exercise , so-called “overtraining”, or from an acute dose of too much exercise. Here are the common clinical scenarios.

1. Continued Hard Training After a New Personal Record (PR)

I recently advised the parent of a highly ranked American distance runner. The athlete had just run two personal record (PR) times in the mile of around 3 minutes and 52 seconds, but he then felt flu-like symptoms and was extremely tired. Over the next several weeks he felt sluggish and could not train well. I ordered the usual initial blood tests that I order for short-term fatigue in athletes: a basic metabolic panel, hematocrit, ferritin, and liver function tests. I primarily provided reassurance, but referred him to a sports cardiologist near the athlete’s home. This clinician agreed with a reduced training load and patience. The athlete subsequently returned to normal and ran a very fast 5,000 meter race about six weeks later.

Such fatigue, in my experience, generally occurs in good athletes who are driven to training hard. The episodes often present after a new PR. Athletic improvement requires working hard to reach a new level, relaxing a bit to consolidate the gains, and then pushing higher. My observation is that many athletes don’t back off to consolidate the gains after hitting a new PR, but push on even harder to get even better. This often results in extreme fatigue and a reduction in spirit and performance. Even if the athlete reduces their training somewhat after a new peak, it often isn’t enough because of the ”cumulative fatigue” from multiple prior hard workout sessions. Creating cumulative fatigue by stringing together multiple hard sessions can be a useful training technique, but too much for too long leads to reduced performance.

2. Post Marathon or Extreme Exertion Fatigue

Many runners go through fatigue and even mild depression after running a hard marathon. A marathon is 26.2 miles, and running it hard is fatiguing even if you are well trained. The adage used to be one day of easy training for every mile of hard racing, but again, many athletes don’t back off. Also, the marathon seems to cause more dysphoria than expected. Some of the dysphoria is the physical fatigue, but good runners don’t do marathons often. Some runners feel as if they missed an opportunity if they didn’t run as fast as they had hoped. That missed opportunity, and having to wait for another chance, causes dysphoria in some people.

Many marathoners are upset with themselves over the dysphoria. I have discussed dysphoria and depression after a cardiac event in the post on how the “head bone is connected to the heart bone”.(2). I call it my “wounded wolf” lecture and it goes something like this:

I tell patients that some depression after a cardiac event (or a marathon or overtraining) is often a normal phenomenon, and is similar to what a wolf does if it gets gored while hunting caribou. The injured wolf retreats to its den and lays low to save calories to heal the wounds because failure to heal the wounds means that the wolf will never successfully hunt caribou again. Dysphoria and laying low is a way to facilitate your body recovering from injury or too much exertion.

I think this analogy often makes sense to patients and athletes, and helps them understand that the dysphoria is usually transient.

Even in non-athlete populations, fatigue at rest is not usually due to heart disease. In this group, sleep apnea is possible, but depression is a frequent cause of fatigue at rest in non-athletes and should be included in the differential diagnosis.

With athletes who I think have over-training fatigue, I often tell them of what Frank Shorter, the 1972 Olympic Marathon winner, said after he retired. When asked if he missed competing, he said something like, “I don’t miss being dead tired all the time.”

Three runners have won the Olympic Marathon twice. Abebe Bikila from Ethiopia won running barefoot in1960 in Rome and again with shoes in 1964 in Tokyo. The Tokyo win was 40 days after his emergency appendectomy. Waldemar Cierpinski from East Germany beat Frank Shorter by 50 seconds in Montreal in 1976. Cierpinski won again in 1980 in Moscow, when the US and other Western countries boycotted the Games to protest Russia’s involvement in Afghanistan. Eliud Kipchoge from Kenya won in 2016 in Rio and in 2020 in Tokyo.

Cierpinski should be removed from the list and replaced by Frank because Cierpinski was listed as one of the East German athletes who used performance enhancing drugs when those records became available to Western journalists after the fall of the Berlin Wall. Frank won in Munich in 1972 and would have won again in Montreal if Cierpinski hadn’t cheated.

I know Frank Shorter from 1988 when we both worked as commentators for NBC’s coverage of the Seoul Olympics. I was at those Olympics in part because I informed my agent at the time, the late Art Kaminsky (1946-2013), that someone at those games was likely to be caught using the anabolic steroid stanozolol. Kaminsky passed this information on to NBC and they hired me as their “Sports Medicine Analyst” for the Games. Kaminsky was a prominent New York City television “talent agent”, who came to represent me (when I had hair) because his wife and my wife were college roommates at Tufts. I knew a lot about stanozolol because it was considered a “safe” anabolic steroid. We had used stanozolol in our studies comparing the effect of oral versus injectable testosterone on cholesterol levels. We documented that the oral stanozolol decreased high density lipoprotein cholesterol (HDL-C) levels by 33% within a week of starting the drug, whereas injectable testosterone had little effect on HDL-C. We have discussed this in a prior post, (3), but oral drugs go directly to the liver post-absorption via the portal circulation so have larger effects on liver products such as HDL Stanozolol was widely used by athletes because it was considered undetectable; it broke down rapidly in the GC-mass spectroscopy detection equipment.

Don Catlin, MD (1938-2024) ran the Olympic Drug Testing Lab for the 1984 Olympics in Los Angeles, and measured drug levels in some of our anabolic steroid studies (4-6). I knew that Don had developed a technique to stabilize stanozolol during testing so that it was detectable. This was not widely known among athletes so I suggested to Art that someone would likely be detected with the drug in Seoul. Amazingly, stanozolol was detected in the urine sample from Ben Johnson, the Canadian who had “won” the 100 meter race. That earned me my first appearance on the Today Show with Bryant Gumble.

I personally learned of over-training fatigue in 1976 after finishing 16^th in the Boston Marathon. I was a cardiology fellow at Stanford. I decided I was going to become a better runner by training harder. So, I decided to increase my training mileage from about 80 miles to 100 miles weekly. Shortly after increasing my mileage, I was in cardiology clinic with Bill Hancock, MD, an excellent clinician and pericardial disease expert. After clinic Bill took me aside and told me that I had done a terrible job, and seemed lethargic. I apologized and promised to do better, but I knew the reason. I was exhausted by the mileage and felt tired all the time.

I knew I wasn’t going to be a very good runner for the reasons presented earlier (7) so I focused on being a cardiologist.

I think most clinicians don’t appreciate how exhausting the training can be for a highly competitive endurance athlete. The fatigue can be extreme and debilitating.

So, when evaluating athletes with fatigue, I remember the Rule:

Start with a dose of decreased training before the million dollar workup. With a history of hard training as described above, almost all athletes get better in several weeks with reduced training. If they don’t get better, then I re-examine the issue and spend the big bucks for all the testing.

1. https://pauldthompsonmd.substack.com/p/biking-75-miles-to-my-tavr

2. https://pauldthompsonmd.substack.com/p/the-head-bone-is-connected-to-the

3. https://pauldthompsonmd.substack.com/p/a-young-fit-man-with-low-hdl-is-on

4. Thompson PD, Zmuda JM, Catlin DH. Use of anabolic steroids among adolescents.N Engl J Med. 1993 Sep 16;329(12):888-9. PMID: 8355760

5. Thompson PD, Sadaniantz A, Cullinane EM, Bodziony KS, Catlin DH, Torek-Both G, Douglas PS. Left ventricular function is not impaired in weight-lifters who use anabolic steroids. J Am Coll Cardiol. 1992 Feb;19(2):278-82.PMID: 1531057

6. Zmuda JM, Fahrenbach MC, Younkin BT, Bausserman LL, Terry RB, Catlin DH, Thompson PD. The effect of testosterone aromatization on high-density lipoprotein cholesterol level and postheparin lipolytic activity. Metabolism. 1993 Apr;42(4):446-50 PMID: 8487666

7. https://pauldthompsonmd.substack.com/p/whats-the-boston-marathon-got-to

#fatigue; #marathon; #exercise; #stanozolol; #WaldemarCierpinski; #FrankShorter; #overtraining; #depression; #AbebeBikila; #EliudKipchoge

The unnamed athlete’s story presented above was published with permission.