Martin Jensen, author of How to Keep Fit Without Exercise ( the lazy man's guide to keeping in shape), lays it on the line. Physical activity is fine—in moderation. But running a half marathon every week is not.
Mild and consistent exercise can safeguard against hypertension, obesity, heart disease, diabetes mellitus, cancer, osteoporosis, age related muscle wastage, cognitive decline and depression.
But overdo it and you are in trouble.
The intensity of effort needed for health benefits is probably around 20 kJ per minute and significant benefits require a regimen using 4000 kJ a week. This translates into 30/45 minutes of mild to moderate exercise per day.
Beyond this limit problems begin. Because exercise increases energy consumption which increases oxidative phosphorylation which generates free radicals not only from phosphorylation but also from extra catecholamine release, prostanoid metabolism, xanthine oxidase and NAD(P)H oxidase activity. In short, exercise increases free-radical production.
If you are an exercise binger or consistently overtrain, you can take anti-oxidant supplements - but don't expect them to do any more than slightly allay the damage. In fact, at high doses, anti-oxidants become pro-oxidant. In other words, they increase oxidization.
A study in women who exercised with varying intensity from 30 minutes to 60 minutes a day proves instructive. Health benefits were apparent in the 30 minute group. But more exercise didn't help. In the 60 minute a day group, the increased benefit/fitness was marginal.
So you don't have to spend hours in the gym or run marathons. You simply need to move occasionally. And, if living long and dying fit is your aim, there are certain other basics:
Less food (including less sugar and meat). And more vegetables in the diet.
A cause or an abiding interest.
A positive outlook.
Little stress. (Try meditation or mindfullness.)
Sensible and simple. But can you live that way? Why not try.
Or do you prefer to die young and have a good-looking corpse?
Read about How to Keep Fit Without Exercise on Buzzword.