Some great truths in this! Twelve Habits of Happy, Healthy People Who Don’t Give a Shit About Your Inner Peace.
Recent high profile athlete cases of heart problems, especially arrhythmias, has had many of us asking several questions about the endurance exercise we do on a regular basis. These include:
- What’s the risk?
- Is it linked to the actual exercise or something else?
- What might you do to mitigate the risk, but still get the benefits of being fit?
It really seems that the evidence is starting to stack up from case studies, to epidemiology, to mechanisms. Let’s explore the issues.
1. What’s the risk?
To sum up (that is, to skip the abstract and comments below and get straight to the next point), there is strong associational evidence that hard and prolonged endurance exercise may damage the heart, which results in sometimes serious heart problems. The overall risk is doubled compared to non-athletes, but the overall risk is still only around 2%.
Here’s the abstract of the study…
Aims We aimed to investigate the association of number of completed races and finishing time with risk of arrhythmias among participants of Vasaloppet, a 90 km cross-country skiing event.
Methods and results All the participants without cardiovascular disease who completed Vasaloppet during 1989–98 were followed through national registries until December 2005. Primary outcome was hospitalization for any arrhythmia and secondary outcomes were atrial fibrillation/flutter (AF), bradyarrhythmias, other supraventricular tachycardias (SVT), and ventricular tachycardia/ventricular fibrillation/cardiac arrest (VT/VF/CA). Among 52755 participants, 919 experienced arrhythmia during follow-up. Adjusting for age, education, and occupational status, those who completed the highest number of races during the period had higher risk of any arrhythmias [hazard ratio (HR)1.30; 95% CI 1.08–1.58; for ≥5 vs. 1 completed race], AF (HR 1.29; 95% CI 1.04–1.61), and bradyarrhythmias (HR 2.10; 95% CI 1.28–3.47). Those who had the fastest relative finishing time also had higher risk of any arrhythmias (HR 1.30; 95% CI 1.04–1.62; for 100–160% vs. >240% of winning time), AF (1.20; 95% CI 0.93–1.55), and bradyarrhythmias (HR 1.85; 95% CI 0.97–3.54). SVT or VT/VF/CA was not associated with finishing time or number of completed races.
Conclusions Among male participants of a 90 km cross-country skiing event, a faster finishing time and a high number of completed races were associated with higher risk of arrhythmias. This was mainly driven by a higher incidence of AF and bradyarrhythmias. No association with SVT or VT/VF/CA was found.
Dr Mandrola says the following:
It’s pretty simple: extreme endurance exercise, done over the long term and with great intensity, increases the risk of arrhythmia. There’s no refuting this strong association. These observations are both plausible and consistent with prior studies.
There should be no surprise when an endurance athlete shows up with atrial fibrillation or some other arrhythmia. We are not surprised when masters-aged athletes suffer from other inflammation-induced maladies, like overuse injuries, heart attacks, infections, and even divorce; why are we surprised they get AF?
But context is important. Previous studies have shown Vasaloppet finishers enjoy lower overall mortality. They smoke less, carry less body fat, and report better eating habits. This bolsters the idea that the lifestyle of endurance racing confers good overall health to most participants. Exercise is good. That observation remains unchanged and unchallenged. In the US, we would do better with an epidemic of over- rather than under-exercise.
It’s also important to emphasize that association is not causation. We don’t know whether excessive exercise alone caused the arrhythmia episodes. There are too many possible confounding variables to make a causation link.
[Grant – true, but see below, there is mounting evidence that it is exercise that causes this]
And . . . just because intense and long-term endurance exercise increases the risk of arrhythmia does not mean athletes should avoid a sport they love. These studies don’t tell us to recommend against endurance exercise. They simply inform both doctor and athlete of possible consequences. There are always trade-offs.
As physicians and teachers, knowledge of the association between chronic inflammation and disease might help us give better advice to our athletic patients. My guess, and it is just a guess, I am no coach, is that the same things that help an athlete avoid AF might also make them faster. Do you think getting adequate rest and recovery improves VO2max? Do you think being content with something less extreme than an Ironman or cross-country ski marathon might be antiarrhythmic? What’s wrong with a fast 10K?
[Grant – see below – I think its more about changing nutrition and training methods, but more work needs to be done]
2. Is it linked to the actual exercise or something else?
This is an important point because the study above is only correlational. However, there is enough mechanistic evidence developing to show that the actual exercise itself might be the cause. A study in forty endurance athletes showed significant signs of right ventricular damage following an endurance event lasting between 3 and 11 hours.
The authors conclude that “intense endurance exercise causes acute dysfunction of the RV, but not the LV. Although short-term recovery appears complete, chronic structural changes and reduced RV function are evident.”
3. What might you do to mitigate the risk, but still get the benefits of being fit?
Overall, I would say that these studies and the broader developing evidence shows that excessive and extreme endurance training increase your risk of heart problems. Like anything else, that’s a population measure. What it actually comes down to is whether it affects you or not. That’s binary, not probabilistic. You will either develop a heart problem or you will not.
So what do you do? If you, like me, like the exercise; you understand the benefits are many and done well outweigh the risk, I would say reconsider how you train. I wrote about this is in a previous blog on polarised training and fat adaptation. Both are likely to reduce the oxidative stress on the body and the time you spend in the prolonged hard cardio zone.
Remember, loads of oxidative stress, glycogen burning, and reactive oxygen species has numerous effects on the body; especially the immune system, tissue damage, and DNA damage. This results in a longer recovery time, more sickness, and higher risks of longer term problems.
Take home messages:
- Exercise is still overwhelmingly good for you. We have a population epidemic of marathon sitting, not marathon running.
- But…exercise taken to extreme might damage your heart, and you won’t know you have done damage until it’s too late.
- New training and nutrition techniques may reduce the stress on the heart and body because you go slower more often, and only occasionally really fast (and probably get fitter), and you burn mostly fat (with your heart using ketones as a fuel which it prefers).
- So, stop flogging yourself at training, eat less carbs – especially sugar, and eat more healthy fat. You might even be faster! You also certainly will be helathier.
OK got your attention. Look I’m really trying to upgrade this blog and send out relevant (and helpful) material, so please let me know what can be improved and what you’d like to see. I’m also really happy to answer any questions, take your success stories in getting fit and healthy and so forth.
Any success or otherwise in carbohydrate restriction is really likely to help others so don’t be shy,
Just drop me an email firstname.lastname@example.org and I will do my best.
From bottom to top that’s Jackson (10), Sam (12), and Dan (3) – all good examples of plenty of potential!
Hi Grant,I met you on the weekend at the New Zealand Society of Positive Psychology after the morning workshop when you showed a group of us around your building. I asked you, as a ‘fellow triathlete’, about your diet and exercise regime. You directed me to your blog which I read and found very interesting. I have started on the road to a LCHF diet 🙂 So far so good.I would really appreciate your advice on an exercise programme. Your current exercise programme sounded really interesting – not as grinding or as long as the programme I use. I need a coach – yes I am a needy person! South Island, ideally Christchurch, would be great if the person follows your ideas! I follow my training programmes to the letter – just the way I am. I would be delighted to be part of a research programme if that would be helpful to anyone. I am 60 years old this year and enjoy competing in Age Group Triathlons.Looking forward to hearing from you.Cheers,Jane
- Your brain will no longer have enough glucose to run purely on glucose for fuel. This means that until your body can re-orchestrate how it can fuel the brain, you will feel crappy. Some people call this the “keto” flu (because you are adapting to a state of nutritional ketosis). The brain will need to use the by-products of fatty acid oxidation (specifically beta-hydroxy butyrate, or BHB) to make up for the lower amounts of dietary carbs coming in. So most people have a period of a couple of days of mental haze. In my experience, if you have a job where you have to actually think, then plan to try to do this phase at the weekend. Training volume will have to decrease too.
- It is possible to mitigate some of the symptoms of the adaptation (dizziness, tiredness, brain fog) by supplementing with good quality medium-chain triglycerides (MCTs). These automatically put fats into your body which mimic the ketones (BHB). MCTs can’t be easily stored as fat and are burned intra-muscularly AND in the brain. Coconut oil is very useful for this. Butter has a good deal of MCTs. Other coconut products do too.
- Salt supplementation can be important. In the adaptation period many people find themselves getting dizzy due to hypotension (low blood pressure). What is likely to be happening is that the kidneys are dumping sodium to keep the sodium-potassium balance intact. So, eat heaps of coloured veggies to get the potassium up. Salt gets salt up too. We could be talking up to 5 g/day in the adaptation period.
- Keeping an eye on dietary carbs is very important as if intake isn’t low enough, you can end up in the grey zone of just feeling crap and never fat-adapting. A few tricks here are to:
- Use a computer-based or smart phone diet diary. If you are in Australia or NZ, the best and free one for this is “easydietdiary”. It links to Aussie and Kiwi food databases. A great learning tool.
- Over-consuming protein can also trick you out of fat adaptation because once you reach your daily requirements, you turn extra protein into glucose through a process called gluconeogenesis. Depending on activity levels, daily requirement will likely be 1.2-1.5 gram of protein per kg body weight. Again, the easydietdiary, or other food counters, can assist in seeing how you compare to this. I’m not saying you need to count food all the time, just get an idea of exactly what has what. Some foods are surprising (e.g., BBQ sauce = 53% sugar!).
- Running track: 10 min easy jog, 10 by 1 min hard on the track, walk 1 min recovery in between. This means I get about 325 m round the track and then walk around to the start of the 400 m again. Actual distances will vary depending on fitness and running ability. That’s the session! Total time: 30 min / Total hard work: 10 min
- Running treadmill: 10 min warm up. Crank the treadmill up to 19.5 km/hr (or whatever speed is hard for you). I do 4 times through 40 sec run, 20 sec rest, 30 sec run, 15 sec rest, 20 sec run, 10 sec rest, 10 sec run, 5 sec rest. I rest for 4 min after 2 cycles through this. This is very hard, but over quickly. You leave the treadmill going at full speed and hop to the side to rest. Total time: 24 min / Total hard work: 10 min
- Bike road: Ride for an hour on a hilly circuit. Go flat out on every hill, cruise down. Total time flat out: about 20 min
- Bike trainer: 10 by 2 min, increasing power every interval by 10 watts from about 340 to 400 w. This really hurts. 2 min rest in between and slightly longer if really hurting.
Thanks Grant. So if he were to basically follow your usual eating programme (first blog) , also with some kumara/yams, this would be a good place to start?Yes. Diet Doctor.com also has some more lengthy resources which I aspire to get up myself in due courseTo increase coconut oil usage, what would you do -besides using it to fry with?
You mention reducing poly unsaturated fats, is this not oily fish, nuts etc? I thought they were good to have…
Quite a bit to get the head around with only a small amount of knowledge on my part! I’ll continue to follow your blog, I’m finding it interesting and I’m slowly getting there!