Exercise 1
Stand with feet apart, arms up. Bend forward to touch the floor then stretch up and bend backward. Do not strain to keep knees straight.

Exercise 2
Lie on your back with feet 6in apart, arms at sides. Sit up just far enough to see your heels. Keep your legs straight. Your head and shoulders must clear the floor.

Exercise 3
Lie on your front, palms placed under your thighs. Raise your head and one leg, and repeat using alternate legs. Keep leg straight at the knee. Thighs must clear palms.

Exercise 4
Lie on your front, hands under shoulders, palms flat on floor. Straighten arms and lift upper body, keeping knees on the floor. Bend arms to lower body. Keep body straight from the knees, arms fully extended. Chest must touch floor to complete one movement.

I discovered Royal Canadian Air Force exercises last year, while interviewing people about their health regimes. Two very different people – 66-year-old Geoffrey Kent, chief executive of the luxury travel group Abercrombie & Kent, and 33-year-old singer Emily Maguire – both cited the RCAF regime as an easy way to keep fit. I was intrigued. Could an 11-minute workout from the 1950s really get you into shape and keep you there?

"Travelling 150 to 200 days a year, I need to exercise in tents and hotel rooms. So I do Canadian Air Force Exercises every morning," says Kent. He learnt them in 1974, after hurting his back in a polo accident. "Somebody taught me the RCAF rudiments, and said that if I kept the exercises up, I'd never have a bad back again. They were right." Not only has his back improved, but he hasn't had a day off work ever since.

As a child, Maguire used to copy her grandparents' RCAF exercises, much to their amusement. Years later, after a long illness, she took the drills up again: "They were easy and short enough to do while I was recuperating. Little and often is much better than going to the gym twice a week and pushing yourself for an hour."

Pilots in the RCAF also kept 5BX going after they quit the flying life. Jim Freeman, a Leading Aircraftman in the RCAF from 1957 to 1962, told me he found "much more use for the exercises after I got out. They're great for sedentary people tied to desks."

The Five Basic Exercises are five minutes of stretches, sit-ups, back arches and press-ups, followed by a six-minute aerobic workout. There are 72 increasingly difficult levels, spread over the six charts into which the programme is split. The frequency of each exercise increases with each level, and exercises become harder with each chart. In chart one, for example, the "sit-up" is raising your head from a prone position. For chart two, you have to sit all the way up.

Speed of progress, and how far up the charts you go, depends on age. A 36-year-old man like me spends four days on each level until he reaches level B, chart three, where he stays.

I've now been doing the exercises every morning for a month. I started at the simplest, but it was too easy. Instead I leapt to the top of chart one (level A+), moving on to chart two four days later, where I've progressed by one level every four days. Chart two is taxing. The press-ups (14 this morning) are particularly demanding, but I have persevered, and went up a level today.

It's been easy to accommodate and stick to the 11 minutes. I live in a small flat, but if you have enough space to lie down, you have room for 5BX. They could equally be done in a hotel room or office; they're taxing enough to give you a little endorphin boost, but they don't make you sweat.

Very quickly, 5BX has become another unexciting but beneficial chore in my routine, like brushing my teeth. Kent treats the exercises as a business meeting that's in his diary every day – "And I never miss a meeting."

But are the exercises doing any good? Lucy Wyndham-Read is an ex-Army personal trainer, specialising in personalised workouts in confined spaces: "This routine is fabulous. Each exercise targets so many muscle groups. It will definitely get you fit. It will be fantastic for whole-upper-body strength, good for bone strength to prevent osteoporosis, and will energise you every day."

She has two caveats: first, you need to be careful with sit-ups which, done incorrectly, can hurt your back. Replace them with a basic crunch: lie on your back, knees up, and lift your head toward your knees without straining. And for exercises that call for you to lie on your stomach and lift your legs and torso, she recommends leaving your legs on the ground.

Does the Canadian military still use 5BX and XBX? The RCAF was dismissive: "This programme was long ago superseded by other fitness programmes, and all the individuals involved with it or who used it have long ago retired."

The RAF, meanwhile, has no official equivalent. However, all members of staff have to complete a physical fitness test every six months. For a man of my age this would entail some running, 18 press-ups and 29 sit-ups. At top level of 5BX for a 36-year-old you do 19 "advanced" press-ups and 27 sit-ups. So 5BX would suit the modern RAF man very well.

For the rest of us, 11 minutes of exercise every morning will certainly leave us trimmer and healthier. However, as Geoffrey Kent points out: "You cannot think 5BX is a panacea for keeping fit. You've got to eat less too."