“Kai veesamma kai veesu, kadaikku pohalam kai veesu” runs the Tamil nursery rhyme. “Swing your arms while you walk, as we go to the shop to buy sweets” sings the fond parent/grandparent to the toddler taking her tentative steps, teaching her how to walk.
Science now provides an answer to why it is good to swing your arms while walking. One would have thought that it would cost energy to the muscles while swinging, so why do so? Or is it only an evolutionary relic, like our appendix — of no particular value, from the great apes, which do so while they do bipedal walking?
Not wasteful
It now turns out, thanks to a recent paper by Collins, Adamczyk and Kuo in Proceedings of the Royal Society B(276, 3679, 2009), that arm swinging is not wasteful, but energy efficient and beneficial. Earlier work by others had suggested that doing so increases walking stability, cuts down of angular tilts, controls arm motions and offers a pleasanter gait to behold.
What Collins and colleagues had done to understand the riddle is two-fold. One is to develop a mechanical model to examine the dynamics of arm-swinging, and then to recruit ten human volunteers to join the experiment.
Each of the volunteers were asked to walk in three different ways; first with the normal swing (both arms swinging together in phase), then with a “reverse swing” (one arm swings forward while the other swings backwards), and thirdly walk with their arms folded or bound physically to the sides.
Oxygen consumption
During each such mode of walking, the physical energy cost to the volunteer was estimated by measuring the oxygen consumption as they inhaled and carbon dioxide release as they exhaled.
It did cost energy for walking in each mode. The surprise, however, was that normal swinging was the least expensive. When one holds one's arms while walking (mode 3 above) it cost 12 per cent more energy than swinging them. And as the volunteers did the reverse or anti-normal arm-swinging as they walked, the metabolic energy rate rose by over 25 per cent.
Arm swinging, of course, involves a direct cost in metabolic energy. But it provides an indirect benefit in terms of reduced metabolic requirement for leg muscles in resisting ground reaction moments such as slipping.
Taking the direct and indirect costs together, an optimum seems to be reached as we adopt the normal gait. The army seems to have realized this in an intuitive fashion in its march past drills.
So much for arm-swinging and walking. Turn now to running. Many of us have admired the Ethiopian marathon runner champion Haile Gabriselassie, and the South African Running Queen Zola Budd. Zola set the running world abuzz when she set a new world record of 15 min 1 sec for the 5000 metre run, and surpassed it with a 14.40.07 the next year — all barefoot.
And Gabriselassie shattered the then world record in 1995 when he clocked 26 min 43.53 sec in the 10,000 metre run. Many of us have often wondered why they ran barefoot and not wear running shoes. They had found it best suited for them, having done so for years.
And the tiny nation, Kenya, has produced 300 runners, who broke the 2 hr 20 min record in the marathon; all of then had learnt to run barefoot and that seems to have helped them run the correct way while they were young. A scientific rationale for bare-footing has now appeared in the January 28th issue of Nature.
There is a fundamental difference in the safety and physiological features between running barefoot and with shoes on. The researchers studied three group of runners: one who always run barefoot, those who always wore shoes as they run, and the third being those who decided to give up shoes and started running barefoot (perhaps Gabriselassie inspired them).
Barefoot better
Those who run with shoes land with their heels on the ground, while bare footers land on the ball of the foot or middle of the foot. Science Daily quotes the lead author Daniel Lieberman thus: “People who don't wear shoes when they run have an astonishingly different strike. By landing on the middle or front of the foot, barefoot runners have almost no impact collision, much less than most shod runners generate when they heel-strike.
“Most people today think barefoot running is dangerous and hurts, but actually you can run barefoot on the world's hardest surfaces without the slightest discomfort and pain.
All you need is a few calluses to avoid roughing up the skin of the foot.” The celebrated Indian painter M.F. Husain would nod in agreement, though Nike and Reebok might demur.
And finally, jogging. The Hindu of 21-2-2010 reports in its magazine section that studies by a Cambridge University group show that jogging and running promote the growth of hundreds of thousands of brain cells in a region that is linked to the formation and recollection of memories.
So, jogging is good to boost your brain power and memory. It would thus seem that all I need to do is to jog twice a week barefoot with my arms swinging, and I no longer need to rack my brain on where I left my coffee mug or my shoes.
dbala@1vpei.org
