My right foot has twenty-six bones, thirty-three different joints and over one hundred tendons, muscles, and ligaments. The sole of my foot has over two hundred thousand nerve endings. These enable me to sense the details of the surface on which I am standing. I can then execute fine adjustments in the positioning of my feet to maintain my balance,
My feet are my suspension system. They cushion my weight for the half of my life that I am awake and standing. If you watch a sprinter at the start of a race you can see how much we rely on our feet to propel us forward. Personal training technology means that we are all tracking our footsteps. We are all striving for the "ten thousand steps a day" that will make us fit. It seems we may only achieve seven thousand steps a day averaged across our lifetime.
Young children can average nearly this much on a quiet day. They can go up to fourteen or fifteen thousand small steps on a busy day. As a Northern European I have a life expectancy of eighty-five. I have an average stride length. This means, my right foot will walk or run over one hundred and forty thousand miles in my lifetime. This is equal to walking around the equator five times!
My foot is on the last lap of its circumnavigations of the earth. It is not surprising that the muscles, tendons, and ligaments age weaken. With age the arch of our foot collapses making our feet broader and longer. Beyond the age of 40 we can gain half a shoe size for every decade. If the arch collapses the feet turn inwards and our gait changes for the worse. We can get pain in our feet but also in our legs, pelvis and back as we try to compensate. The result is that we walk less, which can exacerbate the problem.
This at least was the explanation given to me by Simon Costain of the Harley Street “Gait & Posture” Clinic. He was fitting me with custom insoles for my shoes. They have solved the pains caused by my collapsing arches.
We have some six hundred and ninety muscles in our skeletal system. These are the muscles that keep us upright and allow us to move everything from our eyes to our arms and legs. This leaves aside the muscles of our heart and the rest our internal organs. Our eye muscles, like all muscles, work hard. If you spend one hour reading these Newsletters your eyes will make ten thousand co-ordinated movements.
Our muscular strength peaks at around the age of twenty-five and stays at that level for about ten years. After that it starts to decline, and we lose a quarter of our peak force by the age of sixty-five. This appears to be due to loss of muscle mass. Changes are greater in the legs than the arms. This reduces our capacity for every day muscular activity. It becomes more difficult to carry bags and groceries. Lifting ourselves out of our chair, not to mention putting a bag in to the overhead locker on an plane is harder work. It also influences how easily we can climb on and off buses. These effects are inevitable but are partially reversible. Resistance training for even a short period helps. Eight weeks training significantly improves muscular capacity amongst even ninety-year olds.
Our flexibility depends upon those same tendons and ligaments. With age these stiffen due to the formation of cross linkages in their structure. By the time of retirement, many people have lost eight to ten centimetres of lower back and hip flexibility. They cannot bend over so easily or so far, or to reach out as far. This reduces our ability to climb stairs, shop and even get in an out of cars. It stops us from bending over to reach the bottom shelf in the supermarket or to reach out to the top shelf. One supermarket at least has taken this on board. The Royal Ahold Group, in the Netherlands, has widened the aisles to allow older customers more room to bend over.
Our bodies are powered by oxygen brought to us through our blood. All courtesy of the hardest working muscle in our body – our hearts. Age brings a progressive decline in the amount of oxygen brought to the tissues by the blood. Our heart starts to pump less powerfully. Our arteries and veins are less effective at moving the blood around.
Our maximum oxygen intake determines our ability to undertake our normal daily activities. We all need to walk and climb stairs. Sustained exercise usually requires between thirty-five and forty percent of maximum oxygen intake. Even at that level it will be tiring. Full independence for an older person requires a peak oxygen level of around thirteen ml/Kg/min. This figure represents the volume of oxygen per kilogram of weight per minute. For most people, our body drops below this level at the age of about eighty.
Exercise can improve any muscles strength and flexibility. Exercise can also help our heart. An appropriate aerobic training program can add ten ml/Kg/min to the capacity of a sixty-five-year-old. This is a twenty-year reduction in the decline of the blood transport system. Top-class athletes who maintain their daily training patterns as they age, still have a decline in their maximum oxygen intake. Exercise always helps but it cannot “cure” aging.
If all else fails then the environment will have to bend to the market power of the Third Agers. The Land Transport Authority in Singapore has adapted. Singapore ranks second in the world , after Japan, for healthy life expectancy. Many older people find the speed of the escalators a threat. Singapore, like many other transit organizations around the world, runs its escalators at 0.9m per second. In off peak periods they are now reducing that by a third as an aid to the elderly. They are also considering reducing the speed at peak times in stations used a lot by the over 65's.
Around the world pedestrian crossings are changing. Crossing times are longer for the over 65's. The cars will have to wait. More crossings have intermediate islands to stage journeys. The urban landscape is already being transformed for an aging world.