So, how fit do you think you are?

How can people discover their fitness level? And is it worth knowing? Annabel Ferriman took two self-confessed exercise-shirkers, Caroline Metcalfe and Phil Dunn, along to the gym to find out

THE OVERSTRETCHED WORKING MOTHER

Caroline Metcalfe, a 37-year-old magazine picture editor, was given a mountain bike for Christmas, but she still hasn't tried it out. Her life is so dominated by demands of children and work, that exercise comes low in her list of priorities. Her only regular exercise is a 15- minute brisk walk to the station every morning, between dropping her children off at school and catching the train to work.

"I would love to take more exercise, but I can't fit it in. I work full time, and in the mornings it's a hectic rush to get the children off to school, making breakfast and checking they have all their things. Then in the evenings, I think it is important to spend time with the children, to talk to them and hear about what they did at school and read them stories."

But, paradoxically, the children also inspire her to do so. Caroline, who lives in Loughton, Essex, with her husband, Paul, and children Hannah, 9, and James, 6, would like to become more active in order to provide a better role model. She is slim (9 stone 3lbs and 5ft 5 ins) and feels reasonably fit, running up stairs without getting breathless, for example, but knows that children adopt the habits of their parents.

"I saw a programme on television recently which said that children today were very unfit, because they went everywhere by car and played little sport. Consequently, their heart muscles were not developing. It was frightening and it said that their role models were their parents.

"The funny thing is my husband goes out to badminton once a week, and the children never complain about that. But when I was a member of the school's Parent Teacher Association, and I had to go out to the occasional evening meeting, there was a lot of grief."

At the weekends, the family does take some exercise, going for walks in Epping Forest, for example, but quite a lot of the time is spent socialising with other families. Caroline also takes the children swimming, but that is not real exercise for her, because most of that time is spent with the children hanging round her neck or going down water chutes.

She joined her workplace gym 18 months ago, but has only gone three or four times, because she does not always get a lunch hour and when she does, she prizes it as a time to get away from the phone, to chat with colleagues or talk over ideas with photographers.

She does not want to join her smart, local sports club, because she has nothing in common with the people who go there - "women in lycra sportswear or squat men with loads of jewellery". She did take up water aerobics for a short time on Monday evenings, but it meant that she didn't get home until about 10.45pm.

"Now that the evenings are light, my plan is to take up cycling, to go out for 15 minutes, two evenings a week, after the children are asleep. That appeals to me more than working out in a gym."

THE OVERWEIGHT ADVERTISING EXECUTIVE

Phil Dunn's life is an exercise-free zone. And his sedentary ways are all the sadder when compared with his super-active youth. In his twenties, as a dapper, young bank clerk, he weighed just over 11 stone and took 12 hours of exercise a week; running, circuit-training, playing football, rugby, squash, tennis or cricket, depending on the time of year. "You name it, I played it," he says.

Now, as a 42-year-old advertising executive, he weighs 15 stone and takes less than two hours exercise a week. "My main exercise is pushing my daughter round Greenwich Park on Sunday mornings. I also have a 10-15 minute walk every morning, before dropping my daughter off at the childminder's and getting the train to work."

Phil's problems began in his late twenties, when he broke his neck in a motorbike crash and he was told he should not play any more contact sports. He gave up rugby, but continued with most of his other activities.

Then, 10 years ago, he took an exceptionally busy job, in which he worked from 9am until 8pm, on weekdays, and about four hours on Sundays. He played football for the firm's football team, but found no time to train. Now, although the job has eased off somewhat, he still works until about 7pm.

Finally, the arrival of his daughter, Rebecca, almost a year ago, finished him off."I, and my wife, Jane, who also has a demanding job as a probation officer, share a lot of the work. Our daughter will not go to sleep by herself, so my wife and I have to take it in turns to sleep with her. She has a habit of waking at 2am and deciding it is time to play.

"I would like to take more exercise because I know what it feels like to be fit. I realised that I should tackle it when I clambered up the stairs of the Greenwich foot tunnel last summer and found myself really breathless and thought, 'This is silly.' I used to glide up the stairs of buses. But have I done anything about it? No."

His firm moved into a new building with a gym in it, 18 months ago, and he still has not located it.

"But then I have not looked very hard. A gym does not really appeal to me. I prefer exercising outdoors.

"I should really get up early on Saturdays and Sundays and have a run before my daughter wakes up. I have also promised myself that I will take up tennis again, in the summer, because I really enjoy it."

So how did they measure up in the gym?

Clare Padfield, the fitness centre manager, weighed and measured Caroline and Phil and assessed their blood pressure; what percentage of their bodies was fat, rather than lean muscle; and their aerobic capacity (how efficient the cardiovascular system is at carrying oxygen round the body to the muscles). The results were then compiled to produce an overall score.

Caroline turned out to be fitter than Phil, scoring better on all three measurements. Her blood pressure and percentage body fat were excellent for her age and sex, and although her aerobic capacity was below average, it was better than Phil's, which was poor. Her overall score was a C (average), whereas Phil scored a D (below average).

Clare discussed with both of them the knotty problem of how they might fit some more exercise into their lives. She said that it was important that people did not set themselves unrealistic targets, because when they did not achieve them they dropped out.

"If people are not from an active background, they do not realise the work that has to be done or the commitment that has to be made. Some people also keep meaning to take up exercise, but put it off. Unless they have felt the benefit of exercise, they do not know how much better they will feel."

She advised that Caroline should go to a gym eight times a month (roughly twice a week, though if she missed a session one week she could make it up the next) for about 20 minutes each time. For Phil, she recommended 12 times a month, for 30 to 45 minutes.

Did the subjects find it useful? Phil was very enthusiastic. "The assessment was useful, the advice was useful and I was useless. Everything she told me, I knew, but it was good to be told it. It was a catalyst and I am going to start an exercise regime next Monday."

Caroline was less enthusiastic. "Although she recommended just two sessions of 20 minutes a week, the whole thing takes much longer, by the time that you have changed and showered. The problem for me is that I find exercising in a gym so boring. If it is a choice at lunchtime between a relaxing coffee with friends or pounding a treadmill, there's no contest."

Make exercise a natural part of your daily life

Walking a short distance instead of driving, using stairs instead of a lift, gardening, raking leaves, dancing, the more vigorous types of housework, or playing actively with children. If these are among your daily activities, you may be able stop worrying about how fit you are.

Never before have we been less active. Never before have so many been so worried about their weight. The car and TV have radically changd our lives. Exercise used to be a natural part of life; now it's something that has to be planned. A recent survey found that only a quarter of men and women undertake vigorous activity. One in two people is overweight and one in 10 is obese.

Yet a clearer picture has emerged of the benefits of exercise, and of how little needs be done to make a significant difference to health. Vigorous exercise, such as aerobics, is being replaced by a gentle, more "natural" approach.

The body responds to exercise by a decrease in blood clotting, a reduction in blood pressure and in harmful blood fats, thereby reducing the risk of a heart attack or stroke. Exercise also reduces the risks of cancer of the colon, of osteoporosis and of diabetes, and is important for maintaining an optimum weight, which is vital for health.

Adults should take at least 30 minutes of moderate intensity exercise most days of the week. This might be done by walking briskly for two miles. The problem, particularly for those who are overweight, is finding a way to increase exercise without becoming exhausted or sustaining injury. Jogging, aerobics and walking are too energetic a starting point and may strain the joints. Swimming and cycling are good alternatives - they take the weight off the legs - but are not always convenient. Fortunately, there is another approach to exercise.

The US Center for Disease Control and the American College of Sports Medicine say that short bouts of activity may be added up to obtain the 30 minutes of daily exercise. This might be done by the kind of activities described above.

Make an audit of the exercise you do and gradually increase it. If you feel breathless, don't worry, but avoid exercise that leaves you gasping. When you are comfortable with 30 minutes of exercise from four or five episodes a day, increase the length of one of the episodes. Eventually, you may find yourself enjoying that two-mile walk. OLIVER GILLIE