How Much Exercise Is Too Much? – Revisited

Recently I discussed the notion that there can be too much of a good thing with exercise. Some doctors believe there is a U-shaped curve of exercise and health. Health benefits increase, and risk of mortality from all causes decreases, as amount of exercise increases- up to a point. With too much exercise the benefits can go back down and the risks of side effects like AFIB go up.

An important 2018 study [1] from the Cleveland Clinic, a world-renowned cardiology center, at least partially calls this into question. A found out about this in a post on my fellow blogger Tony’s site, and he also has some interesting comments there.

The Cleveland Clinic researchers came at this from a different angle. Previously, for example in the Copenhagen Study [2], researchers have looked at mortality and disease risk vs. volume of exercise, often self-reported in questionnaires. Instead, in the Cleveland Clinic study, cardio fitness was directly measured and correlated with long-term mortality. The results were readily available because the clinic routinely performs exercise stress testing on patients. From these fitness levels can be precisely determined. With results of over 122,000 patients over the years, good statistics could be accumulated on fitness vs. all-cause mortality. Brilliant! I don’t know why this has not been thought of before. Cardiologists all over the world run these tests, and I have undergone one myself. I’ll describe that below.

But first, the bottom line: no U-shaped curve was found. No upper limit. The fitter you are, the less long-term risk of mortality from any cause. Period. Those with “high” level fitness had much lower risk than those with low. But those with “elite” level fitness had even less.

The results were classified into fitness categories as shown in the table:

An exercise stress test is a test, usually on a treadmill but sometimes on an exercise bike, where you start out slowly and every couple of minutes the intensity goes up. You’re hooked up to an ekg so your heart rate is monitored and arrhythmias can be detected. Both fitness levels and intensity can be precisely measured in this test. In my case, a little over 2 years ago (shortly after I’d been diagnosed with aortic stenosis), it was a treadmill test. I started out walking, leisurely, on a flat surface. Piece of cake. Then a couple minutes later I heard a beep and it got faster, but still not bad. Then another beep and the treadmill threw in some incline and got faster. This kept happening, relentlessly. Eventually I was running hard up a 10% incline. Definitely not a piece of cake. All this time my heart rate was being recorded along with speed and incline. The tech shut it down when my heart rate reached 171. I actually felt like I could have gone a bit harder although the barf threshold was not far away. I felt like I had passed the test with flying colors. I later found out that some arrhythmias had showed up on my ekg which is why the test was stopped. This was an early indicator of my afib, a side effect of my aortic stenosis (which is thankfully gone now).

How to Explain the Difference With previous studies?

Volume of exercise does not correlate directly with fitness. Even if you measure something like MET-minutes per week of activity, which captures a combination of intensity and volume, it is not the same as fitness. That is because there are optimum ways to train to achieve fitness, like the old maxim “work harder not smarter”. I’ve discussed previously techniques like polarized training and interval training that are thought to achieve good fitness benefits with minimal health risks. In contrast, many people who become enthused about recreational activities do a lot of volume at a moderately high intensity level, which is actually not the best for fitness or health. A lot of coaches call it “no-man’s land”. A person with a lower volume of training, but with higher intensity thrown in, can actually be fitter. Previous studies, that just measure volume of exercise or even “Met-minutes”, will include lots of people training inefficiently at high volume. The Cleveland Clinic focussed on the bottom line, fitness.

Based on the Cleveland Clinic results, I think a case can be made that some experts have overreacted to the “U-shaped” evidence. For example, cardiologist Dr. James O’keefe entitled his youtube talk on this subject “Run for your life! At a comfortable pace, and not too far“. Maybe it should have been “at a comfortable pace most of the time, with some high intensity thrown in once in a while”.

I personally train more than 90 minutes a day on average. Probably 90% of that is walking or leisurely hiking or biking. About 10% of the time I work out hard, at strength training or brisk hiking or biking, typically done with intervals. That much volume is unnecessary, but I find the leisurely stuff pleasurable and relaxing. My favorite fitness role model, Clarence Bass, at 80+ years old, spends a lower amount of time, maybe about 45 minutes a day doing brisk walking. And a couple times a week he goes really hard at strength training and cardio. In his words “I walk and I sprint, I don’t do anything in between”. I’m pretty sure I’d show up as high fitness for my age if the Cleveland clinic tested me, while Clarence would undoubtedly be elite.

The most important thing is to get off the couch!

The emphasis in this post is “the fitter your are the better”. But the most important health improvement occurs in those who were previously sedentary and get moving. The Cleveland Clinic authors published another paper based on the exercise test results which shows that your fitness is more important than your age in predicting risk of dying. I’ll go over that in the next post.

References

  1. Mandsager, K, et al, “Association of Cardiorespiratory Fitness With Long-term Mortality Among Adults Undergoing Exercise Treadmill Testing”, JAMA Network Open, 2018.
  2. Schnorr, P, et al, “Dose of Jogging and Long-Term Mortality: The Copenhagen City Heart Study:, Journal of The American College of Cardiology, 2015., available online at https://www.sciencedirect.com/science/article/pii/S0735109714071745

4 thoughts on “How Much Exercise Is Too Much? – Revisited

  1. Hello, I’m 58.5y/old I’ve maintained a reasonable level of fitness until 56.5yrs/old when involved with major injuries, including TBI: subdural hematoma and bleeding along the majority of & inside the left temporal lobe as well as 8 tendons in the right forearm severed, 7 tendons to the hand were reattached and the hand was saved with 98% use returned over 12 months.
    I used to have good power to weight strength & very good endurance with a longest continual indoor row world record @ 53 yrs/old, I would train up to 8 hrs a day 5 to 7 days a week in the lead up to the record which is still current and was for almost 2 yrs the overall record for all age groups, @ 78hrs (679,179mtrs) allas now the 80hr barrier has been broken so I have my work cut out for when I attempt to break the 60-64 yr record.
    After the injuries I had 11hrs of surgery (1 neuro surgery, 1 x orthopedic), some 300 sutures in total, a craniotomy, lost the radial artery, too badly damaged to save???) almost had the radius severed, minor radial nerve severed as well, 6 months rehab to get my right hand to regain function & re-align without flopping laterally, & had an extra surgery to remove scar tissue @ 6 months, I went back to the gym & started at a slower pace 3 times a week and found out what fatigue felt like for the first time in decades. after 3 months I was getting fitter stronger with better cardio & moved up to 5 days a week, after 12 months i was feeling pretty good and would do a 45-60 min weight circuit with either a 5 or 10 km indoor row to finish. and then go to a dance class, twice weekly to socialise & improve co-ordination, balance etc.
    at the 18month mark, with 12 months at the gym & feeling good I had a massive seizure in my sleep, which freaked my wife out who doesn’t handle scary situations very well. I was sent home without any special instructions, no information on what to look out for, no propholactic anti-convulsant & Then one week later I had a second seizure where I face planted into our granite bench top without knowing or feeling it. I spoke with the head neuro who I have since been assured is avery experienced but somewhat jadded specialist, (near retirement).
    Luckily I enjoy research & was determined to find out the best plan of attack to get back to normal, healthy & seizure free. Once you have two seizures you are classed as an epileptic, can’t drive, nor ride push bikes, not supposed to swim climb ladders etc. I’m on low dose anticonvulsants & have been seizure free since, I should have been put on propholactic anti-convulsants after the first seizure which would have kept me from being classed as an epileptic. I would have retained my independence etc. My research shows a plant based diet is a key component for brain health, but it also showed that new neuronal growth itself (which is a sign of normal healthy brain recovering from abrasions can trigger seizures as can scar tissue), many other issues can trigger seizures, and nocturnal seizures which mine are classed as, can be associated with an endocabinoid imbalance in the cerebro spinal fluid(CSF) in people who don’t partake in cannabis, which is me, but I have learned since that pot smokers can have seizures? The brain is complicated. I have always had restless legs, just now far more pronounced, My wife suggested I do some pushups, which I did, with my feet up on a park bench, I banged out 50 pushups without a problem and for 15 minutes had a clear head, anti-convulsant medication side effects include fatigue, head fog etc. I later found doug mcgough’s information on very slow movement exercise, which I trialed and found it did fatigue the muscles far more quickly than what I was used to. I could do 15 decline push ups doing a 7sec down, 7 sec up routine. I then found a paper asking if slow or fast movements were better. the conclusion was that the best movements were a combination & that any movement slower than 6 seconds was detrimental for muscle growth; the best movements this study deduced were fast & explosive on the loaded push or pull then a slow & controlled phase of 5 seconds on the return phase. I am specifically looking to build muscle to compensate for the rapid muscle loss after the accident and the association with longevity as TBI patients can lose 10 years off their lifespan which I’m not crazy about as my family has a history of early deaths.
    As far as how much is too much and which techniques are best for exercise, my take on it is that if you’re a body builder, then load up the weights & slow down the return section of the reps, but if you’re after endurance, than go hard for as long as you can building in stages over time, I started off doing 2km on the rower then jumped to 5km’s than to 2 x 5km’s then 10km’s then up to 3 x 10km’s on 10 resistance then 7 then 5 while doing weights in between. It comes down to what the individual wants to achieve as body builders generally don’t have endurance & endurance athletes don’t carry too much muscle…

    Liked by 1 person

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s