Idle Theory

The Natural Pace of Work

Why Don't Grazing Horses Gallop?

In Idle Theory's view, living creatures attempt to minimize the duration of work. If so, why don't they perform this work as rapidly as possible? Why don't they run around when busy? And for that matter, why don't busy people, out shopping or commuting, also run around? After all, if they ran, they'd get work done quicker, wouldn't they?

The answer is that such a view does not take energy into account. Anyone who runs from place to place, from A to B, accelerates their body mass from standstill to running speed in some short interval of time. And in order to come to a halt again, they must deccelerate their body mass from full speed to standstill. Since this acceleration up to full speed requires work to be done, with more work with greater acceleration and higher top speed, it follows that the more rapidly some animal moves from A to B, the higher its energy expenditure in accelerating, deccelerating, and overcoming resistance to motion (friction) while travelling at full speed. In the case of a grazing animal, which moved from tuft to tuft of grass, with each tuft having some small energy content, the expenditure of energy in sprinting from tuft A to tuft B may exceed the gain in energy from consuming a tuft of grass. Running from one tuft of grass to another, a grazing animal may actually lose energy.

But equally, if a grazing animal moves at a snail's pace from one tuft of grass to another, barely accelerating and deccelerating at all, it may spend so long in going from A to B that it will expend more energy with its basal metabolic rate (breathing, maintaining blood circulation, etc) over the long period it takes to move from A to B than it gains once it has reached B, and eaten another tuft of grass.

If so, and there is a net loss of energy from moving from A to B too rapidly, or too slowly, then there is most likely a happy mean where it moves from A to B at some optimum speed that maximizes net energy gain. And this optimum might be called the natural speed of motion, or the natural pace of work - where the 'pace of work' translates as power output.

Other factors may also need to be taken into account. The legs of animals may be regarded as pendulums with a natural swing period, and swinging their legs faster or slower than this natural swing period will entail performing more work, either in accelerating their legs or braking them. The natural speed of motion of an animal may simply be defined by the length of its legs. However animals don't have fixed length legs, and when animals run, they raise their legs, and thereby shorten them, and shorten the swing period. So animals with variable length legs may have a variety of natural harmonious speeds.

Also, since muscular activity releases combustion products, these require to be exhausted before further work is done. In an internal combustion engine, the engine performs work when the fuel-air mix in a cylinder explodes and drives a piston. For the remainder of the cycle, the piston returns to its former position, forcing exhaust gases out of the cylinder. So an internal combustion engine isn't actually continually performing work, but only doing so about half the time it operates. It alternates between work and relaxation. A semblance of continuous work is achieved by using several cylinders in line, such that one or more are working while the others are 'relaxing'.

The longer any effort is sustained, the lower the work rate. Long distance runners don't sprint all the way: that way brings exhaustion. In general it would seem that the longer the duration of any activity, the greater the need for periods of relaxation. A sprinter's efforts are concentrated into a few seconds. Football games last 90 minutes, with a 15 minute half time. And while footballers periodically sprint, they spend the remainder of the time walking slowly or standing still. A game of cricket may last an entire day, but batsmen only swing momentarily at a ball, and fielders only intermittently run to stop flying balls. A game of golf may last for several days, but entails moving at walking pace, and periodically striking a ball.

If there is a natural pace at which any work should be performed, it will necessarily be a relatively leisurely pace, rather than with the mightiest exertion. If this natural pace is exceeded, or retarded, net work done per unit time falls.

The same applies to mental work as physical work. After all, a brain is simply another organ that performs some kind of work, and requires energy to power it, just as computers need an electricity supply. One can no more mentally work continuously than one can physically work continuously. And the greater the mental exertion required, the longer the periods of compensatory relaxation needed. It is necessary for office workers, whose work is essentially mental in nature, to have coffee breaks, cigarette breaks, lunch breaks, and to just gaze out of the window for a while now and again. If this is not permitted, exhaustion will follow, and less work will get done overall. If hard-working executives in high pressure jobs suffer 'burn-out', it is because they have been either been overworking themselves, or have been overworked.  

Idle Theory

Author: Chris Davis
First created: 29 March 2006