This is the final post in the series, and is probably going to be the most speculative. Seeing as I am living in Australia, we'll take the Australian Government's health advice first:
Adults. The Australian Physical Activity and Sedentary Guidelines recommend adults aged 18-64 years are: active on most, preferably all days each week. do between 150 to 300 minutes of moderate intensity physical activity or 75 to 150 minutes of vigorous intensity physical activity each week. And do muscle strengthening activities on at least two days each week.
As with every guideline or piece of health advice that comes from "reputable" sources, it is a bit vague and involves a lot of guesswork. However, this is quite understandable because it is a general guideline after all, and people vary in the amount of exercise they need.
Daily, these guidelines amounts to about 20-30 minutes moderate activity, or 10-20 minutes vigorous activity per day, and they do advise activity on every day.
As always, I like to look at quality and quantity of exercise from an evolutionary perspective. From this standpoint, what is the answer to the question, "How much should we exercise?". The answers is, "Just enough to feed yourself, escape predators, and do other essential activities".
Exercise for our ancestors was only a necessity. The rest of the time it would have been important to conserve energy. And the vast majority of the exercise our ancestors would have been doing was walking and running. Ever wonder why you like lying on the sofa doing nothing? Well, for our ancestors, conserving energy was a very important part of their survival.
Fast-forward to the current era, and most people struggle to exercise enough, and many avoid running especially. I've explained the biomechanical necessity of running and walking for health in previous posts, so I won't dwell on it here.
I don't have anything but gut feeling to back this up, but I have a strong instinct that we don't need to exercise very much at all, if we do it by doing the things that make humans unique biomechanically efficiently (i.e. standing, walking, running, throwing, etc).
I have made no secret that I am a great admirer of Functional Patterns. Its founder, Naudi Aguilar is a fair athletic specimen these days, and he claims to only exercise about once a week. Check out the video below and see if you believe that, many don't, but I'll tell you why I do.
His claim is that if you exercise efficiently, and then not run yourself down with too much exercise, that levels of testosterone will rise and you'll build and maintain muscle absolutely fine with limited workouts.
On a personal anecdotal level, I have for much of my life been an obsessive exerciser. I used to exercise basically everyday, mostly pretty intensely. I wouldn't say I over-trained the way many do, but I would often have a day in the week when I was so tired I could barely do anything remotely physically taxing through a general body feeling of exhaustion.
This feeling of exhaustion was kind of nice though, and I think many people feel this way about exercise. Along with the endorphin rush effect, feeling physically tired for the rest of the day after a workout is relaxing, and you definitely feel less guilty about putting your feet up.
The trouble is that, especially if the exercise is having a compressing or detrimental effect on your biomechanics, this tiredness can be physically stressful and in that state you can't produce testosterone as you should do or fully recover in a way that is healthy (for women, I am less concerned about testosterone production, and more on recovery). You are getting a pleasant psychological and physiological effect in the feeling of having done something, but in reality this effect overtime is leading you to biomechanical dysfunction which could lead you to come crashing down to earth with injury.
I think this is a sign of exercise addiction. Pleasant short-term effects that lead to long-term harms. The trouble is that the vast majority of people do not consider exercise to be harmful, and I would definitely have counted myself in this category until very recently. I have always known about the phenomenon of overtraining, but the definition of it is usually again too short-term. It is really about being too tired from too much exercise for maybe days or weeks afterwards that prevents you from training properly or making improvements in the days and weeks ahead. Rarely, if ever, do people look years down the line and think whether the training they are doing is causing biomechanical damage.
It isn't just looking at the long-term bigger picture, but also it is possible that people would find better results with less training (especially if they are biomechanically efficient with their training).
Taking myself as an example once again, I often found that some people would train much less than me when I was younger, yet had better results, both in physical appearance and in performance. How it is that this guy goes to the gym twice a week for 45 minutes at a time and looks carved out of wood, yet I workout 4 or 5 times a week for over an hour at a time and just don't get the same results? I always used to think it was all about diet or genetics, and surely they play a role, but could it also be they were simply functioning better biomechanically than me, and by training less were also not wiring in their dysfunctions so deeply as I was?
What I have noted as I have got older, however, is that these people who were prime physical specimens in their 20s are now no longer, and I have caught-up and gone past most of them. I don't claim this is solely because of the way I train. It is probably more down to a less stressful lifestyle, as I have never worked a stressful, full-time job. I have mostly found work that is either not especially physically or mentally stressful or I simply haven't done much of it. It recent years, I have worked on a limited basis for myself in a line of work of trying to improve my physical health. As physical and mental stress has mounted on friends and peers as they age, it has lifted off me and the physical results are showing.
How much exercise should we do then?
This is a long preamble for me to essentially say, "I don't know", because it is a deeply complicated question down to the huge amount of variables involved with each individual person. But I think that if you are a decent biomechanical specimen who knows how to move properly like Naudi Aguilar or a gifted athlete whose movement is naturally efficient, the answer is probably only once or twice a week, for as little as 30minutes to an hour at a time, but this is predicated on what kind of exercise is being done. If you exercise in a way that is in tune with human evolved biomechanics, Naudi is probably right, maybe once a week is all you need, perhaps even less.
For the rest of us mere mortals, we probably need more, not least because it is necessary to change our biomechanics to become more efficient, which needs a decent amount of hard work and practice.
If you aren't on the road to biomechanical improvement, however, perhaps the guidelines from the Australian government mentioned at the beginning of this article are about right for other aspects of health. However, people do need to begin to understand that doing any old exercise is going to lead them to physical breakdown in the end, where they simply will not be able to follow these guidelines. When that eventually comes along is anyone's guess for different individuals; some are lucky and they can exercise regularly into old age, but most are not.
Finally, I think walking holds a bit of a key to how much exercise is good for you. There seems to be quite a large comparison with the amount of steps taken in a day with mental and physical health. If walking is not painful for you, then walking every day is surely an excellent thing to do, and brings health benefits. However, walking ends up becoming an issue for many people (and especially running), and even if pain is not present while walking, bad gait in walking can cause compression in tissues and lead to other negative health outcomes.
Its a tricky subject, but yet again a lot comes down to gait, i.e. how you walk and run, and being able to do these most basic of human movements. There are so many different exercise modalities out there, and as I have explained throughout this series of blog posts, they have some issues surrounding them. In these turbulent times of Covid, even if all the gyms were to shut, and classes and sports canceled, you'd still be left with the absolute key to human health through exercise, the basics of walking and running. Learn how to do them properly and the amount of exercise you need to be healthy, for you personally, will start to reveal itself to you, and you won't need to search for guidelines concerning this question.