Why dogs are good for you

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I’ve had three family dogs – all border collies. The one in the picture is Bluey, a 15 month old red/white border collie. He’s a friendly and active fellow, on a whole food meat and other stuff based diet.

I wanted the smartest, most active dog because my view was that they would need exercise and that would force me and the family to do more exercise.  So is that likely to work, or is the dog more trouble than he’s worth and you just spend more money and can’t holiday when and where you like?

Well the original big dog in the research into dogs and physical activity was Prof Adrian Bauman and his dog Schroeder (a Jack Russell). Schroeder is the first dog I know to be a published author on a research paper.

Anyway, Adrian is back with a team reviewing the benefits of dog ownership on physical activity in the latest issue of the Journal of Physical Activity and Health.

There are now 29 studies looking at this, including one by me almost 10 years ago.  I showed that dog ownership wasn’t enough; you needed to have at least a middle to big sized dog!

So what has the latest review shown? “Approximately 60% of dog owners walked their dog, with a median duration and frequency of 160 minutes/week and 4 walks/week.” Dog owners on average are slightly more active than non-dog owners, but the effects are small. We don’t know if giving someone a dog helps them be more active. In other words, we need dog intervention research!

So is it worth having a dog?  Probably. There are numerous benefits, including some extra activity. Are there hassles? Damn straight there are.  Mine crapped in the kitchen overnight and I was the one who got in trouble for it, and I even cleaned it up!

There’s something else about being out with a dog too.  The sheer primal nature of it, the ability of the dog to draw you into the moment of being alive.  Running on an empty beach.  Chasing seagulls.  It’s great fun.

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Is exercise damaging my heart?

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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:

  1. What’s the risk?
  2. Is it linked to the actual exercise or something else?
  3. 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?

A recent study published in the European Heart Journal shows several things. Actually, there is a really great comment in a blog by cardiac specialist Dr John Mandrola.

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.

Be the best you can be

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(pic: the entrance to AUT Millenium where I work)

I’ve wanted to start a blog for quite some time now. The trick is to get the technical skills together well enough to actually know how to run one and do it regularly. Well, I’m just about there.

What will I blog about?

I am really interested in the science of how we can be the best we can be. This crosses disciplines such as biology, medicine, pubic health, and productivity management. The cornerstones are nutrition, exercise, sleep, neuroscience, psychology and well-being. I’ll be covering these topics under the broad heading of the Science of Human Potential (the name of this blog).

I’ve been interested in human health and performance for my whole career. I started in psychology then into sport and exercise psychology, then into public health especially physical activity then obesity.

There have been some twists and turns along the way which might help to give a view of why I do what I do and where it can go.

About me

Sport and exercise has always been a massive part of my life. From an early age I played rugby union, learned to sail and race, and eventually ended up in the high school rowing squad. Rowing at my high school had no room for anything but high performance. So I was introduced to this at age 13. From there we won national championships most years. The combination of the sheer physicality of the sport and the team work and individual excellence required both mentally and physically really defined my teenage years and who I could become as an adult.

Being fit and involved in some sort of high performance activity has been part of my life since then.

I finished bachelors, Honors, and doctoral degrees in psychology at the University of Auckland by 1994. At the same time I had got into triathlon as a sport. I ended up racing semi-professionally. That’s code for “was never quite fast enough to earn a decent living, so had to supplement prize money income by working“. In the end I raced professionally in several world championships in long course triathlon, ironman and duathlon. That was great fun, and the skills and work ethic I have learned from triathlon are important to me.

The extra benefits from the high performance sport world, especially triathlo,n include:

  • I met my wife Louise because of triathlon. She ended up also as a professional triathlete, a better athlete than me. We’ve been married since 1995 and have three boys – Sam, Jackson and Daniel. Louise also started Vitality Works, a workplace health company acquired by Sanitarium in 2012. Vitality Works has allowed both of us to benefit from a huge amount of professional and personal development in health and well-being.
  • I figured out early that a high performance life is just as much work as a low performance life, so you may as well take the high performance life. It just requires a bit more work up front, but frankly you avoid work later and you get more choices.
  • I have the skills to stay fit and enjoy maximizing my biology for my own personal peak performance.
  • I still get to compete at a reasonable level in triathlon and running. This is cool because the age group triathlon and running groups are really fun, and you get to hang out with people of a similar performance, health, and happiness mindset.

My academic career began with part-time teaching in the Psychology Department at The University of Auckland during my PhD tenure. I moved to Australia (Central Queensland University in Rockhampton) and worked in the School of Psychology there for nearly 10 years. Most of our spare time then was dedicated to triathlon training and racing with Louise. I wasn’t going fast or far in the academic world at that point. Enter Kerry Mummery.

Kerry Mummery is now the Dean of Physical Education at the University of Alberta. He really mentored and started me on the journey to becoming a decent academic. We worked on several physical activity and health projects together. The most notable was 10,000 Steps. This started as a whole community project and morphed into a nationwide program which is still running successfully today.

This was the entrance into public health proper for me. I started at AUT in 2003 after the birth of Jackson our second son. Back in Auckland and into a new country with plenty to do. That’s when things really took off. I had the good fortune to have several great staff members and PhD students under my guidance. Almost all of these are still with me.

The highlights in the last decade are:

  • Working with dozens of talented doctoral and masters thesis students
  • Being highly successful in obtaining research grants and funding. This is the life of an academic and you live and die by this success. We are up over $20 million in funding.
  • A solid and respectable publication record. Ditto above. Important for gauging success. But by itself is unlikely to put much of a dent in the universe.
  • Being involved in Vitality Works. This has put a dent in the universe and allowed me to develop more formally into peak performance, well being and neuroscience.
  • Being the youngest full professor around for a while. That wore off as I aged!
  • Moving our work beyond physical activity into obesity, well-being, productivity, and nutrition/weight loss. Most recently the work we are starting in metabolic efficiency and weight is likely to put the biggest dent in the world.
  • Starting the Centre for Physical Activity and Nutrition and eventually morphing that into the Human Potential Centre at the new Millennium Campus.

So that’s where I’m at. Where I want to go now, and with this blog, is to explore the science behind what helps us “be the best we can be.” It’s an emerging and multidisciplinary science. Let’s go!