When exercise backfires

I’m an inveterate exerciser. Ever since I quit smoking at 20 after dabbling with it in college, I became a runner, and ultimately a triathlete. Now I regularly swim, cycle, do weights and floor exercises, and have recently taken up Pilates. 

I also have had a broken shoulder, broken hip, and innumerable small setbacks chasing fitness.

I recently listened to a podcast interview with Ross Edgley, a British ultra-marathoner who became the first to swim around the British Isles, a distance of 1780 miles in 157 days. He topped that off with a swim around Iceland, 1000 miles in 114 days. He also completed a non-stop swim of 318 miles down the frigid Yukon River—56 hours, without stopping, sleeping, or touching land.

Challenging age limitations

61-year-old grandmother DonnaJean Wilde just entered the Guinness Book of Records with the longest sustained female abdominal plank—at 5 hours.

At the recent Ironman World Championships in Kona Hawaii, the oldest contestant was 83-year-old Robert Plant (not the Led Zeppelin frontman) who swam 2.5 miles, cycled 112 miles, and topped it off with a 26-mile marathon run. 

Plagued with mechanical issues on his bike and severe leg cramps, Plant did not manage to finish before the deadline. He completed the feat in the dark, hours after the race leaders crossed the finish line. He was not destined to join the ranks of Ironman competitor, Hiromu Inada—the oldest athlete to ever complete the Ironman World Championship, who finished Kona just shy of his 86th birthday a few years ago.

But Plant was in good company. This year, even many of the vaunted elite male and female favorites crashed and burned amid the sweltering lava fields of the Big Island. Some went out too fast and had nothing left in the tank only a few kilometers short of the tape and just collapsed.

Which begs the question: Is this good?

When are the benefits of exercise eclipsed by cumulative wear and tear—the risks to joints, bones, and heart? After all, exercise is a form of hormesis, a therapeutic dose of stress—like sauna, ice plunges, or intermittent fasting—that can promote healthy adaptation and resilience. But there’s a “Goldilocks Effect”—too little, too much, just right. 

The New York Marathon tragedy

We’re still reeling from the shock of the tragic death of a young ostensibly healthy and well-trained 24-year-old woman during this month’s New York City Marathon. She collapsed just short of the finish line and suffered irreversible cardiac arrest. She was said to have succumbed to rhabdomyolysis.

How was it that she died, and not any of the other 60,000+ competitors, many of whom were less fit, older, and some of whom were racing despite considerable medical challenges?

Rhabdomyolysis occurs when excessive stress causes muscles to break down, releasing their contents into the blood stream. Myoglobin from muscles turns the urine brown and can clog the kidneys, sometimes necessitating dialysis. 

Worse yet, damaged muscle releases a torrent of stored-up intracellular potassium; excess blood levels of potassium can trigger life-threatening arrhythmias. 

Dehydration, electrolyte depletion, and heat are risk factors for rhabdomyolysis; the day was not particularly hot and hydration opportunities abound on the marathon course. Was she prey to some unfortunate, hitherto undetected, risk factors? 

Why her?

There are known genetic predispositions to rhabdomyolysis, genes that lower the threshold for muscle breakdown under conditions of exertion or overheating.

There’s also the possibility of some unsuspected congenital heart anomaly that could make a runner more prone to life threatening arrhythmias. 

Another possibility is a drug interaction with high-intensity exercise. Antidepressants like SSRIs and SNRIs—frequently prescribed to young women—mess with thermoregulation and can push heart rate into the “red zone” with intense effort. 

Hopefully, a thorough post-mortem investigation will yield clues that might protect future generations of endurance exercisers from a similar fate.

How much exercise?

Studies of exercise often render contradictory verdicts on the “how much?” question. Some show distinct benefits from less than the 150 minutes/week currently recommended by health authorities. Light household chores, gardening, a leisurely game of pickleball, or far fewer than the vaunted 10,000 steps/day can score distinct health benefits.

Then there are the studies that say we need far more than 150 minutes per week to notch significant health dividends. And, they suggest, mere walking doesn’t cut it. High intensity interval training (HIIT), where you’re completely gassed, and resistance exercises are claimed to be essential for optimization.

Moreover, the ultimate payoff of all that added effort remains controversial. Some studies suggest decades of sweaty exertion yield mere months of additional lifespan; others claim that, regardless of its impact on longevity, increased health-span is the jackpot achieved with peak fitness. 

Overdoing it?

There’s no question that there can be deleterious consequences of overzealous workouts. For one, there’s the wear and tear on joints. Physical therapy centers abound with athletes suffering from injuries. By the same token, studies show that moderate exercise actually helps aging adults avert osteoarthritis. 

While exercise confers substantial heart benefits, there are diminishing returns for ultra-distance athletes. They sometimes develop enlarged hearts and are known to be more prone to arrhythmias like atrial fibrillation. 

 
More atherosclerosis?

A surprising finding among ultra-distance athletes is that they have more atherosclerotic plaque than healthy controls. I well recall my surprise at finding that one of the fittest athletes I ever treated—who commuted by bike 30 miles each way to work daily, rain or shine, and competed in arduous multi-day Rocky Mountain endurance races—had a coronary calcium score over a thousand!

This is attributed to the enormous wear and tear on the coronary artery walls—during high output exercise sometimes reaching six times resting average—with shear forces that repeatedly stretch and deform the endothelial lining.  

What mitigates heart risk in these athletes are their high fitness levels, and the finding that their plaque is the more stable, inert, healed calcified type, in contrast to more dangerous, rupture-prone soft and sticky plaque. 

Additional woes . . .

There are also short-term consequences of over-exertion; marathon contestants are notorious for developing upper respiratory infections within days of completing their events. The reason: Immunosuppression that develops when the body’s reserves are exhausted.

Both women and men who overdo the mileage can experience suppression of sex hormones—low T in men, and cessation of periods in women. 

Exercise doesn’t just expend energy—it begets energy; it promotes mitochondrial biogenesis—causing the energy powerhouses within our cells to proliferate and become more efficient. But mitochondria can also burn out. Early in my career I cared for a legendary ultra-marathoner who could barely shamble into my office. I suspected that he had completely fried his energy circuits with sustained, uninterrupted running—compounded by a highly-restrictive vegan diet and a refusal to take even the most basic supportive supplements. His mitochondria had finally given up the ghost.

Overtraining syndrome

 Then there’s the dreaded OTS—overtraining syndrome. Committed athletes are very familiar with OTS—they’re often on the bleeding edge of performance, constantly invoking “no pain, no gain”. 

But zealous amateurs can also be prey to OTS. It’s cardinal signs:

• Unrestorative sleep 
• Early morning wakeup with an accelerated pulse
• Inability to raise the pulse to accustomed high levels with exercise 
• Lack of motivation
• Decreased performance (“pedal-to-the-metal” but no acceleration)
• Irritability
• Fatigue
• Susceptibility to injuries
• Muscle pain
• Lightheadedness
• Frequent infections 

Determined exercisers often try to push through OTS, deepening its hold. When I feel overtraining symptoms looming, I try to head off OTS with a few days of rest, and it usually resolves. But once full-blown OTS sets in, it can sideline an athlete for weeks or months.

The remedy for deep-seated OTS is tantamount to a prison sentence for avid exercisers: Total rest—for as long as it takes. Then, the temptation to resume full activity looms, and can result in a setback. Very gradual ramping up—well below an exerciser’s customary capacity—is essential for true recovery. Reining it in is excruciatingly hard for active people. 

My exercise philosophy 

Nietzsche is famously quoted as saying: “That which does not kill us makes us stronger.“

These days, my cardinal rule when embarking on a hard event is “Don’t die!” I remind myself to pull back on the throttle when I feel gassed. Especially when you’re older, make exercise a challenge, but not an injurious ordeal. 

I like my muscles to feel lightly toasted after a challenging workout, but not burnt to a crisp.

Or, as Kenny Rogers sang, in an anthem that shepherded him through 82 years of life:

“You’ve got to know when to hold ‘em
Know when to fold ‘em
Know when to walk away
And know when to run . . .”