Not All Exercise Is Beneficial: The Physical Activity Paradox Explained

When you work a physical job you are typically working for 8-12 hours straight with little break and you often do repeated, but non-ergonomic activity that leads to joint damage such as standing on hard floors for 12 hours; bending over repeatedly with poor form to pick up a heavy tool; kneeling on hard floor; etc. Often, because of the long hours and fatigue, individuals resort to bad form to rest their tired muscles.

Working out for leisure activity, however, is often higher intensity for a much shorter period of time and typically very controlled ergonomically to reduce joint stress / wear. Professional and enthusiast lifters know that when you can no longer maintain proper form you stop lifting. Runners train and build their bodies over a year or more to handle up to marathon distances. When it is your occupation you don’t have such a luxury, so bad form happens immediately and repeats for an entire career.

Further, people who work out are usually making a conscious effort to improve health and make dozens of other small decisions such as improved diet and hydration that would be difficult to account for or control in a study. A nurse, plumber, or construction worker may be in good physical shape and making healthy choices or not. If they are not they are putting more physical stress on their body. A runner is making on e very clear healthy choice that probably correlates to a bunch of other healthy choices.

It seems pretty likely to me that working a physical job late in life is correlated with lower income and wealth, which we know correlates to worse health outcomes. I would hope the study would control for that, but it's not clear from the article.

You apply the appropriate level of stimulus for where that person is currently and they exeperience positive growth. You apply too little stress and there is no adaptation or a reversal. If you apply too much, you get injured and go into reverse. I think this applies to any kind of challenge, be that physical like exercise, but also mental like learning, work, etc.

The more honestly you can evaluate where you are and what you can currently handle, the better you'll be. Don't be lazy but don't let your ego or dreams of being a big shot lure you into biting off more than you can chew.

> "consistently working in an occupation with intermediate or high occupational PA was linked to an increased risk of cognitive impairment."

Translation from pseudo-scientific weasel-speak: if you don't have much of an education, and stick to manual job all your life, you will probably end up even dumber.

Connecting this to the idea of not all exercise being beneficial is cognitively deficient.

Exercise will not produce cognitive function. Lack of exercise will contribute to its decline, but you have to use your brain to train your brain. People don't exercise to get smarter.

I have a lot of questions. Most of which center around controlling for other factors.

1. Is it income adjusted?

2. Is it diet adjusted?

4. Is it stress adjusted?

5. What kind of physical jobs? Or is it all jobs that aren't office oriented?

6. Is being a housewife considered a physical job? If so, have they looked at rates between housewives and women who work office jobs?

7. Is it hours worked adjusted?

I have a lot more but I think people get the point.

I think what many people misunderstand about physical exercise is that it only works if you pair it with quality recovery.

You need quality food with good mix of macro and micro nutrients at a right time. And you also need good sleep and low life stress.

If you don't eat right or don't have good sleep or you are already in high stress (for example because of your job) then the results from your exercise will be limited.

Also, another point is that training is targeted exercise. You plan for the right kind of exercise, when it is good for you. Even if your activity does not seem like planned a lot like hiking -- you still plan for the hike to happen when you feel like doing it and you choose hiking that will satisfy you physically (not too much, not too little). When you do activity at work you rarely can control what you do and how much of it.

> consistently working in an occupation with intermediate or high occupational PA was linked to an increased risk of cognitive impairment."

I think this conclusion might be totally unwarranted: I suspect they did not control for how much the study subjects used their brain over the years of the study, let alone other correlates of jobs involving more physical labour.

The body has limits that can be expanded through training. However, exceed the limits and you will be injured. The key is to train up to your limits consistently.

Given that most jobs with PA in later life are low pay, I wonder how much nutrition and stress were factors.

This reminds me of the scene in Conan the Barbarian (with Ahnold) where he is taken a slave as a child and has to push a treadwheel till he is grown, the implication being that the slave labor was the reason for his heroic physique.

The words "causation" and "causal" do not appear in this article.