When it's cold and dark outside, swimming in a heated pool is an ideal way to improve your fitness - in theory. The problem is that churning out length after length of front crawl is a slow way to burn calories and as dull as dunking your face in a bucket for half an hour. Fortunately, there is a way to break up the monotony of long swims in the form of this interval-training circuit.

Swimming pools are thoughtfully constructed in lengths of around 25m, a fact that Men's Fitness has exploited to bring you this flat-out, fat-burning workout without making you check your watch or count endless lengths. If you swim in a pool the size of a pig's trough, just double the lengths.

This workout uses different strokes, techniques and those strange pieces of foam that clutter up the sides of most pools to burn calories in double-quick time and tone every muscle in your body. And every exercise can be done along a regular swimming lane.

How to do this workout
Choose a quiet lane in your local swimming pool and place a float, some hand paddles and a pair of swimming fins at one end. Perform the following exercises in order, taking no rest in between. Once you've completed one circuit, rest for two to three minutes before going again. You should complete at least two circuits. Leave at least one day between workouts.

Start
Do a gentle warm-up of ten slow lengths with at least two different strokes. No synchronised swimming allowed.