WITH ADVANCES in medicine, nutritional awareness and healthier lifestyles, we're living longer than before. But what happens to our bodies as they age - and why? There are many theories about why we age. Three are widely accepted: the genetic theory says we have a built-in inherited time clock; the free-radical theory says that our bodies' ability to produce antioxidants diminishes; and the hormonal theory says cardiovascular illness, osteoporosis and menopause are all partially triggered by a reduction of natural hormone production that begins in our 30s and accelerates as we age. The answer is probably a combination of all three. A recent landmark study by the US-based MacArthur Foundation, Successful Aging, concludes that genes determine 30 per cent of ageing, and that the other 70 per cent is lifestyle driven. Adam Menhennett, director of Physical Harmony Personal Training in Hong Kong, links physical activity to an improved quality of life. 'One of the biggest areas of concern for most people is tissue elasticity,' Menhennett says. 'As we age, our tissue mass is less able to repair and even to just stretch and return, hence the wrinkles, creaky joints and aches. Most people are concerned with the change in appearance, but bone health, muscle balance and biomechanics are much more important. As well as a balanced diet, appropriate exercise has been shown to be the best way to ensure all-round, good health.' Ageing as a cause of death is only a recent phenomenon, according to www. biology-pages.info. Humans, and their pets, are the only animals that die of old age. In the animal kingdom, death is caused by starvation, predation, infectious disease or harsh environments. As late as 1900, humans were still dying primarily from infectious diseases. A child born in that year in the US had a life expectancy of 47 years. Today, women in modern environments have a life expectancy of 80, and men 74 years. According to the World Health Organisation (WHO) in 1997, because exercise lessens the risk of chronic disease and affects body function, a person's level of physical activity can have a direct influence on the age at which they die. Benefits of physical activity for older people include regulating blood sugar, stimulating hormone production and enhancing sleep patterns - all of which have been shown to affect longevity. 'In my experience, as people age, they're concerned that exercise will do more harm than good,' says Hong Kong personal trainer Chris Marshall. 'I'm often asked if it's worth it. The answer is always a resounding yes.' So long as a doctor has given the all-clear, there's no age barrier to exercise. 'Exercise prescription is individualised - it's just a case of adjustment,' he says. 'For example, treadmills are used with caution because of possible balance issues, and strength training before was seldom emphasised for older people because of concerns about blood pressure, but that's all changed now. Low- to moderate-intensity strength training exercises are encouraged.' Menhennett agrees. 'As people age, they're more interested in their bodies and staying fit,' he says. 'Most people have got the message that exercise is good, and the baby boomers in their 40s, 50s and 60s today are extremely interested in things like nutrition, hormones and body fat percentages.' The fitness industry has responded and there's now a large number of courses and programmes specifically designed for older exercisers, he says. 'Although the best exercises, no matter what age a person is, are those that we enjoy and are pain-free, when a person begins to age it's best to concentrate on activities that promote stability and mobility, balance and agility,' Menhennett says. With the onset of older age, fitness should have less to do with getting slim and looking buff, and more to do with overall health. The emphasis is on giving older people the freedom to easily carry shopping bags, tie shoelaces, get out of a car without assistance or contemplate a game of beach football without the prospect of pain the next day. Noel Ching Ka-mun, nutritional adviser at Hong Kong age-management clinic Cenegenics Medical Institute (HK), says that both aerobic and anaerobic exercise help slow the rate of ageing, as each has specific benefits. 'A combination of resistance training, cardiovascular exercise and flexibility training produces the best result,' he says. 'One thing is for sure: the older we get, the more important it is to engage in a healthy lifestyle centred around good nutrition and physical activity. 'Body tissue, including bone density, degenerates with a corresponding drop in our metabolic rate. 'We lose on average 3kg of muscle mass per decade, more after 45. We get shorter. Fat increases as a percentage of body weight. Strength, energy and speed decline as does our aerobic capacity.' Ching says the thymus gland - in charge of the immune system - shrinks, so immunity to illness is reduced. Good cholesterol reduces, and bad increases. 'The skin thickens and dehydrates, resulting in wrinkles,' he says. 'It becomes harder to achieve a deep-sleep pattern. Hearing, vision, and taste sensations decline, as does kidney function.' Ching is quick to point out that there's also good news. 'A healthy lifestyle - which includes good eating habits, proper nutritional supplementation and hormonal checks - can, without a doubt, help stave off the signs of ageing,' he says. All the usual dietary advice applies. Choose whole grains and good fats, eat more fruit and vegetables and avoid caffeine and alcohol, Ching says. But as we age, it's also important to take supplements, because with modern eating habits it's impossible to meet daily vitamin and mineral requirements through food alone. Likewise, hormonal checks are essential because hormones affect every aspect of our physical and mental well-being. If, as Bette Davis said, 'old age is no place for sissies', we'd all do well to get moving.
