Seeing people holed up inside apartments around the world has worried me for many reasons, including people’s access to vitamin D and the necessary exercise to maintain health.
On an earlier thread John Davidson said he had been part of a UQ study on the use of high intensity exercise, and as a result he tries to get 36 mins intense exercise every week at above double his resting heart rate. In this post I summarise the findings of a number of articles that have recently come my way.
I wear a Fitbit charge 3 which tells me my resting heart rate is around 60 beats per minute. However, I simply can’t push my heart above around 110 bpm with walking/running. My lungs and heart handle it all OK, but my muscles can’t put out the energy to raise my heart rate above around 110 bpm. So does this matter? Read on.
The New Scientist recently ran an article Higher step count linked to lower yearly risk of death, up to a point.
They used 4000 steps a day as their baseline, “because this is easily achieved by someone who drives to work and sits at their desk for the whole day.”
When I did rehab after heart surgery we were told that the average person with an office job in Brisbane could do as little as 2500 steps per day.
Using 4000, the researchers found that:
- taking 8000 steps was associated with a 51 per cent lower risk of dying per year, and taking 12,000 daily steps was associated with a 65 per cent lower risk of dying per year.
But taking more than 12,000 steps a day didn’t seem to be associated with a further reduction of risk of yearly mortality.
The results held true “regardless of sex, race, level of education, health condition and whether a person smoked or drank alcohol.”
So what about running over walking?
Steve Haake’s recent article in the NS Is running or walking better for you? Here’s what the science says tells us it is basically about the work you do, not the time you take to do it. Intensity saves time, but doesn’t yield health benefits as such.
That’s the short answer, and it is counter-intuitive.
The long answer is that the article reports a number of studies, each with it’s own research parameters and design. The central one starts with a base of a person resting for a day without moving, which they nominated a one MET (metabolic equivalent). One MET for an 80 kg person doing nothing is “around 1920 kcals per day)” just to keep our bodily systems ticking over.
- All physical activities can be expressed in METs, and there is now a Compendium of Physical Activities that contains an eclectic mix of them described using this system. This elegant solution to the definition of exercise has three categories: light exercise up to 3 METs, moderate exercise between 3 and 6 METs and vigorous exercise for anything over 6 METs (see “Measuring the burn”).
Strolling, at about 2 METs, is light exercise, while walking briskly is in the middle of moderate at 5 METs. The transition to running at around 7 kilometres per hour is where exercise enters the vigorous category. A really brisk walk and a slow run are roughly the same, in terms of effort and calories burned. But is this true of their health benefits too?
They found that preparing for a single marathon can make your cardio-vascular system four years younger. It would take an awful lot of walking to achieve that effect.
The biggest gains come by changing nothing to something. From there on it is a case of diminishing returns for additional effort.
Surprisingly, though, other researchers cited in the article have found that running helps activate all kinds of repair and maintenance mechanisms in the joints. There is a sweet spot, where running contributes to body health, but if you go beyond that sweet, spot wear and tear will count. The studies quoted were not long term. The cycle from funding to publication often limits research.
This article did not look at a the spot were increased activity yields negligible gains, so does not conflict with the ideal of 12,000 daily steps cited above. Moreover the focus of these studies was primarily health benefits, whereas the first cited article was looking only at mortality.
- A 2017 meta-analysis including more than 125,000 people found that 3.5 per cent of recreational runners had osteoarthritis in the hip or knee compared with 10 per cent of sedentary non-runners. Yet 13 per cent of elite runners who had taken part in international competitions had such osteoarthritis. For recreational runners at least, it seems there is a sweet spot at which running protects against osteoarthritis.
The QU study may have been identifying the shortest time commitment necessary to gain the same sweet spot which others have identified.
Intuitively I suspect that testing oneself to a reasonable but not dangerous degree may have additional benefits. My fitbit tells me I do an average of around 14,500 steps per day, and includes short bursts of what to me is maximum effort as I walk up steep embankments, or push a barrow or mower up a steep incline. I feel this must assist in maintaining my lung capacity. Yet my wife would suffered from low lung capacity tells me that intensity of exercise has never been emphasised by her health professionals.
As an aside, about 10 years ago I was starting to get a bit of arthritis in the joints. Someone said “chia seeds”. One dessert spoonful a day in the breakfast serial and the pain went away. From that time on my ‘bad’ cholesterol was also noticeably lower. This is anecdotal and may be coincidental, not medical advice!
More interesting stats from the article include the finding that every hour of running typically adds an extra 7 hours to lifespan. That’s from a study which found that:
- between the ages of 44 and 80, someone who runs 2 hours per week will spend a total of 0.43 years running. This would still provide an average “bonus” of 2.8 additional years of life on top of the time spent running.
Presumably the 12,000 steps is on the flat, as we see here:
I understand that strength and impact training contribute to bone density, but the focus here is on running and walking.
Born to run
Marathon runners sometimes look to me like a set of hips and legs, with the smallest torso, head and arms necessary to provide balance. I guess a bit like a kangaroo, which is said to have the most efficient movement system.
Back in January 2019 in the Scientific American Herman Pontzer addressed the issue of how we evolved to run (Humans Evolved to Exercise – pay-walled). He says that for humans to be healthy they need to run, unlike their ape cousins.
He says that chimps and bonobos walk about three kilometres a day, gorillas and orangutans less. Chimps and bonobos climb about 100 metres a day, equivalent to an extra 1.5 km. Orangutans are much the same, gorillas less.
Pontzer says that about 15,000 steps per day is seen as ideal for cardio-vascular health, and to avoid metabolic disease. He says hunter-gatherers typically cover about 14 kilometres a day on foot. Again he emphasises total output rather than intensity.
In evolutionary terms 4.4 million years ago our ancestors were as comfortable walking on the plains as climbing trees, but still had feet that could grip limbs. From there walking/running gradually took over in order to extend hominids’ range into less productive landscapes. By the time of homo erectus 1.8 million years ago, our open stride was firmly established, the spine had developed an S shape, the pelvis enlarged and bowl-shaped to pivot the bone structure, the upper limbs and fingers shortened, while the lower limbs lengthened. Hominids walked all over the planet. Our bodies stored more fat and we became able to sweat, contributing to endurance.
Our movement is much more efficient that that of the apes. For example, our leg muscles are 50 per cent bigger than chimps, with four times more output.
Pontzer says that every organ changed, even down to the cellular level to become part of this story.
The brain, he points out, rewards running, so we have the so-called ‘runners high’ as a response to aerobic exercise. Indeed a whole range of chemical functions throughout the body complete the story.
He puts the American adult average at 5000 steps a day, which makes them vulnerable to disease, such as diabetes. If we veg out on TV an Australian study found that every hour shortens our lives by 22 minutes, so the 63.5 hours to binge-watch Game of Thrones will cost us a day.
He emphasises a wide-ranging balanced meat and plant diet. Finally our sleep time is less than that of the big apes, to allow for greater activity.
There is an excellent figure in the article illustrating the changes, which I can’t access online. I had this figure on file:
This one illustrates how we differ from other apes:
This one identifies the main changes associated with bipedalism:
Tuning up or regenerating the immune system
Finally, Graham Lawton’s article How to fight infection by turning back your immune system’s clock is worth a read if you can get it (I’m never sure whether New Scientist articles are pay-walled or not). He says that some 60-year-olds have the immune system of a 40-year-old, some are more like an 80-year-old. That was Shai Shen-Orr, an immunologist at the Technion-Israel Institute of Technology, who also tells us:
the immune system is immensely, mind-bogglingly intricate. “It is the second-most complicated system in your body after your brain,” says Shen-Orr. It consists of hundreds of cell types and signalling molecules controlled by some 8000 genes, interacting in a network of near-infinite complexity.
The article goes into the role of additives such as Vitamins E, D and zinc. In those cases care needs to be taken, because excess doses can be harmful.
On exercise the article recommends 10,000 steps per day. Another technique mentioned is caloric restriction:
- The strategy works because it switches on an evolutionary adaptation to starvation, which prioritises repair and survival pathways over growth and reproduction. Calorie-restricted animals tend to be leaner, fitter, metabolically healthier and mentally sharper than those that eat at will. They also have a stronger immune response.
The technique can involve permanent diminution of energy intake of up to 60 per cent, which requires discipline beyond most of us.
Seems that some starvation brings out the best in us in the struggle for survival, but it is not a state we would chose.
One variation is:
- the 16:8 diet, which involves completely eschewing calories for 16 hours and only eating in an 8-hour window. Even done once a week, this is an effective way of slowing ageing and strengthening the immune system.
Simply keeping our weight in check has benefits. Obesity is said to be worse than smoking.
All the above is relevant to improving our chances in the face of a threat like Covid 19, where the fittest have a better chance of survival. In general, diet and exercise have a powerful influence on health, supported by good sleep. I haven’t mentioned mental well-being, where I’m sure that equanimity, an orientation to the needs of others, and a sense of purpose make a difference. In relation to the latter, we do need to come to terms with living sustainably within planetary boundaries.
In sum, we need to rethink about how we perceive human well-being, and notions of human progress beyond but including the economics-health binary, at a time when realistic hope is in short supply.