Years at the debt swap desk has slouched his spine, drooped his shoulders and shrunk his chest. His biceps have the tone of dumplings and his quadriceps carry him only a few hundred yards before crying for rest. His belly seems to protrude beyond his area code. He is disgusted, he wants to get into shape and he wants to get fit.
BIL wants to achieve three goals: build his endurance, strengthen his body and live longer. The muscles of his body will have to wake up from years of sloth. He has to coerce his muscles into action; he has to stretch them, work them, and build them. It will help him if he understands how muscles work.
The basic unit of a muscle is its cell – a long spindle shaped structure often called a fiber, which contains energy yielding materials and thousands of rod shaped protein filaments that have the ability to contract. Muscle cells in a group form one cohesive functional motor unit and a muscle has numerous motor units. A single neuron – ‘motor neuron’ – controls one specific motor unit.
When the brain commands a muscle to contract, molecules of acetylcholine transmit this message through the motor neuron, generating an electrical impulse, which crosses the muscle cell membrane and travels through its interior channels. Protein filaments in the cell respond to the signal. They shorten in length by sliding over each other. Stimulus from one motor neuron contracts multiple cells in one motor unit and if more strength is needed multiple neurons participate and recruit many motor units. The result: a muscle contracts.
But brain cannot voluntarily contract of all the muscles; some are beyond its will. Heart, for example, beats to a different drummer – the autonomic nerves and chemicals in circulation. Heart also beats faster to respond to the oxygen needs of voluntary muscles.
What is the source energy supply to muscles? (Nature is wiser than one of the disastrous products of evolution – politicians – and unlike them nature has solved the energy problem of muscles.) A complex molecule – adenosine trriphospate or ATP – is the answer. Muscle cells contain a small amount of stored ATP, which suffices for first five seconds of activity. For next fifteen seconds of contraction the cell converts a precursor molecule – ADP – into ATP. If the vigorous activity lasts longer, muscle must manufacture new ATP. It does so by breaking down glucose.
Body utilizes glucose in two ways: by using available oxygen – aerobic; or without oxygen – anaerobic. After the first fifteen seconds of activity body resorts to anaerobic path of producing ATP. This process lasts about forty more seconds and anaerobic metabolism of glucose produces pyruvic and lactic acid – the cause of muscle fatigue. If the muscles continue exercising, body must utilize pyruvic acid for ATP synthesis to supply more energy. This entails the use oxygen or aerobic system, which ensures a large supply of ATP for the muscle to endure a longer period of activity.
Muscles have two types of fibers. Type I or ‘Red’ rely on aerobic metabolism and enhance endurance. Long distance runners have more type I fibers. Type II or ‘white’ fibers metabolize ATP faster, have more powerful contractions and accumulate lactic acid faster. Weight lifters and sprinters have more type II fibers.
Recall BIL’s objectives: endurance, strength and longevity. Endurance depends partly on the ability of the heart to supply a steady stream of oxygen to the muscles by pumping oxygenated blood. He can build endurance or cardiovascular fitness by aerobic path by exercising major muscle groups at a steady pace for a long period, say thirty minutes daily. He can jog or bike. To strengthen his heart he has to increase his heart rate to seventy to eighty percent of the maximum predicted rate for his age. (Here is an approximate formula to calculate maximum heart rate: 220 minus age.)
BIL can improve his strength by utilizing anaerobic path by lifting weights or exercising against resistance. Short spurts of vigorous activity like repetitive sets of weight lifting will build his muscles. The heart accelerates to above eighty percent of the maximum predicted rate with this hard-core anaerobic training. He could also increase his endurance considerably if he knew his lactate or anaerobic threshold: the level of exercise at which lactic acid produced in the muscle starts spilling into circulating blood. Some interval training regimens include repetitive cycles of a sprint for thirty seconds followed by rest for two minutes.
The foregoing explanation above is simplistic. Most sports use all mechanisms of energy generation and a combination of exercises will ensure his first two objectives.
How about BIL’s third objective: longevity – can he live longer? He can enhance his chances by longer life by following the second axiom of life, which has nothing to do with exercise: wear a seat belt. But BIL hardly drives now; he sits at home watching his stocks tumble on the computer screen. Can exercise prolong his life?
Highly active people can expect to increase life span by about three to four years. Starting late, even after age sixty is beneficial. And even moderate exercise is good though vigorous exercise – accelerating the heart to seventy percent of maximum rate – is better.
In a study published in The Journal Of American Medical Association, the investigators studied 13000 men and women who participated in an exercise program for eight years. Depending on intensity and perseverance of exercise, they classified the participants into five groups: from ‘least fit’ to the ‘most fit’. The study revealed that people who exercised the most – the most fit – had much lower death rates than the least fit. The age-adjusted death rates in men fell from 64 in the ‘least fit’ group to 18.6 in the ‘most fit’ group. For women the death rate dropped 39.5 to 8.5 from the least to the most fit.
Exercise benefits the body in many ways. It reduces heart attacks up to forty percent, improves bone density, fights depression, decreases hip fractures and may even prevent colon cancer. Old people can improve strength and balance and reduce injuries due to falls.
BIL, who has seen the highs and lows of hedge funds, has learned every silver lining has a cloud. Bitten once by the Wall Street, he is twice shy of the gym. He wants to hedge against the underside of exercise. Any consequences he should worry about? Yes. It is long life.
Body has too many organs and with age they wither. Jogging improves heart, muscles, bones but not kidneys, pancreas, spleen, liver, marrow, hair, teeth, gums, gonads, guts, brain, skin, eyes, ears. The old heart, primed with exercise, may keep pumping blood to the brain that can’t remember, to joints that don’t stretch, to gut that can’t digest. While almighty heart keeps ticking, other decrepit organs are just marking time. That brings us to the first axiom of life – this time a warning: exercise may make you last longer.