FOR OSCILLATORY MOTION
Push Ups one of the most tiring oscillatory
exercise for which the "center of gravity" of the body is
raised up and down. Obviously, the useful final work is zero.
However, the athlete is getting very quickly exhausted in 10 to 20 oscillations or so.
Therefore, the coefficient of work performance is:
n = 0 out / muscle work = 0% = zero%
This is because muscle energy is first transformed into potential energy when the body (center of gravity) is raised up, but when the body is lowered back, this potential energy is completely lost into heat. The athlete gets very hot, sweats and gets quickly exhausted, limiting his capacity of spending energy to 10 - 20 push ups or so.
In general, for every
oscillatory-periodic motion of a muscle, its energy is
transformed to some kind of work and/or potential energy, which
in no way is turned back in to muscle energy.
This inability of muscle function to turn potential or any other form of energy back into muscle energy lowers the coefficient of efficiency significantly, even makes it equal or close to zero - 0%, in most practical cases, walking, running, exercising, moving the hands , the body or parts of the body up and down.
It is important to include some form of exercise in your daily routine. Today many adults and children lead sedentary lifestyles due to television, computers, and online rpg games. Walking on a treadmill while watching television is good exercise but it may be difficult to play online rpg games while walking. Gamers may be able to play their favorite rpg games online while riding a stationary bike though.
Raising and lowering the legs or the body for
walking and mostly running is an oscillatory motion that raises
the "center of gravity" of lower leg or the "center of gravity"
of the body (in case off running) to 0.2 to 0.6 m or more.
The muscle energy stored in potential energy, E = mgh, when the leg or the body is raised is lost into heat when the leg or the body is lowered to normal height.
On the other hand, the energy needed to keep the body's constant speed on an horizontal road is minimal to practical nothing - equal to that of air friction.
Therefore, the efficiency for a walking and particular running human or animal is very very low. Estimated to less than 1% for walking and less than 0.1% for running.
Therefore, walking and particular running for human's and animals is a very very energy wasting process that only abundant atomic energy may richly and adequately provide.
On the contrary, for most mechanical engines that they return back kinetic, potential energy or other forms of energy, their efficiency may be as high as close to 100%.
Another direct proof of this argument of lower human and animal energy efficiency is the comparison of human efficiency and that of the system human bicycling.
The system man-bicycling running on a horizontal road is at least of the order of 100 times more efficient than man walking or ruing on the same horizontal plane.
If we assume that bicycle's efficiency is n, the man's alone efficiency < n/100.
The efficiency superiority for bicycling is due to the pedals. With pedals, when one leg is lowered the other leg is simultaneously raised. In this way, the pedals have the ability to offer-exchange the potential energy of a lowering leg back to the raising leg potential, instead spending and wasting a new energy each time one leg is raised.
Therefore, pedals enable the legs never to lose their potential energy, instead pedals allow the same potential energy to be carried from leg back to leg. The only energy, thus spent for bicycling on a horizontal plane is that due to friction. Though, for a human the energy spent for walking or running is that of friction-relatively very small plus the potential energy that is wasted into heat for raising the legs or the whole body in case of running. In running the body moves with jumps that raise the whole body above the ground to some 0.4-0.6 when the both legs do not touch the ground. In this case, the energy lost Erunning = m rghr is much much more tiring, compared to walking Ewalking=mwghw, for mr >>mw and hr >hw.
Even Bicycling Scientists, realizing Atom Bomb's Energy = mc2 ,
Sometimes may not realize that
for Bicycle and Man's Energy = mc2 , their corresponding Efficiencies are:
for Bicycle n >99% and for Man n <1% !
Original Document by
Panos T. Pappas
Copy righted 2003
This original article maybe reproduced in part or in whole
only with due ethical reference and notification to its author.
January, 6, 2003,
P. T. P.