The tennis body

Key muscles used
Thighs, arms and torso.

The look
A lean, muscular physique with strong legs, broad shoulders and back, thanks to the explosive power used to dash around the court, volleying and serving. Tennis is a mostly aerobic activity with short, sharp bouts of anaerobic activity (such as very fast net volleying, which wouldn't be sustainable for long periods). Body fat levels average around 16 to 18% - lower than the average individual's 25% but not as low as that of endurance runners and swimmers.

Professionals undergo "plyometric" training, which includes exercises such as leaping up from a squat position, ie jumping when muscles are already lengthened and inuse, which is specifically designed to increase the thickness of the muscle, giving players the strength and speed in the legs vital for serving and speeding across the court.

Professional players have higher than average hand-grip strength as well as thicker forearms, and greater hand and wrist width on their dominant playing side. These are developed by controlling the racket head through critical phases of the stroke.

The yoga body

Key muscles used
Shoulder girdle, deep-core muscles of the torso, and legs.

The look
Power yoga, or Ashtanga yoga, postures involve the body's weight being supported by arms, shoulders and legs in a variety of flowing stretch sequences. Muscular definition is particularly marked in the upper torso, shoulders and arms.

Since the muscles are being lengthened while in use, yoga bodies tend to be lean and long. Muscles, including the deep abdominals, are further worked to provide the necessary stability in balancing postures. The extent of the muscle definition will depend on the intensity of the sequence and the length of time held in each posture - a gentle Hatha yoga class, for example, is unlikely to turn you into Madonna.

The runner's body

Key muscles used
Thighs and calves.

The look
The muscle definition we see in good marathon runners is visible thanks to low body fat - characteristically in the region of 7% - rather than excess muscle mass. Thigh muscles are long and lean: successful long-distance runners are genetically predetermined to use the maximum amount of oxygen from each breath and, through training, they will also have developed a more efficient blood capilliary network, helping to transport oxygenated blood to the contracting leg muscles.

Upper bodies, however, can appear puny. Some studies have shown that while the bone density of the lower limbs may be high, bone density measures of the upper torso and arms can be nearing osteoporotic scores. This is thought to be due to the calcium leaching from the upper limbs to help fortify the bone tissue of the lower limbs.

The walking body

Key muscles used
Legs, torso and arms.

The look
Get your technique and pace right and you've got a lean and upright torso with a well-defined, pert bottom; plus streamlined thighs with a relaxed shoulder line. Walkers can have great buttocks as, unlike recreational jogging, with each stride the hip fully extends, targeting the gluteal muscles of the bottom, creating a firm, shapely and uplifted posterior.

When aiming to increase your walking pace, think about speeding up your arm swing. Not only does this help the legs naturally speed up, it also helps with arm definition, opening up of the shoulders and alignment of the neck and the upper torso.

Abdominals need to be actively working as you walk to help stabilise the pelvis and improve toning of the gluteals. Try visualising your fingers being able to slide in between your belly and your waistband. The latest abdominal research suggests that training the abdominals in an upright position, as one ought to when walking with good technique, is more effective than traditional sit-ups as it builds the muscles in a functional way, doing something the body was designed to do. Aim for a consistent 7,500 steps a day and, with good pace, you'll see a difference.

The swimmer's body

Key muscles used
Chest, upper back, torso and the hip extensor muscles of the legs.

The look
Broad shoulders, defined torso and chest. The pectorals and latissimus dorsi muscles of the upper back create a wide "V", tapering to a narrow waist. Very muscularly defined without looking bulky. Pretty much the definitive all-body aerobic workout, top-class swimmers will have low body fat without looking sinewy.

While the arms may appear to do all the work, the true power for fast propulsion is initiated from deep-core abdominal muscles, so competitive swimmers have very flat abdominals. They also develop enviously pert gluteals (bottoms), thanks to the contribution of the hip extensor muscles in stabilising the pelvis, streamlining the body through the water.

While swimming is intense aerobic activity, the body fat levels of swimmers may not be as low as with other professional athletes due to the cool water triggering the body's thermoregulatory system which encourages the body to carry a little insulating fat.

The Spinner's body

Key muscles used
Legs, especially the back and front thigh muscles - quadriceps and hamstrings - and the muscles of the upper torso, which contract to help hold the body in position.

The look
Spinning is predominantly an aerobic activity but the leg muscles can also be challenged in a similar way to weight training (anaerobically), depending on the resistance level that the stationary bike is set to. This creates a physique with low body fat, but with a potential for chunkiness in the thighs. There is a tendency for a roundness of the shoulders as leaning forward creates a shortening of the shoulder adductor muscles (which we use to shrug), drawing the shoulders in.

Spinners may find themselves with a rounded, fuller posterior because, while the gluteal (buttock) muscles will be contributing to some of the leg propulsion, the seated position means that the hip extensor muscles of the gluteals and hamstrings (thighs) which lift and tighten the butt are not being used.

The Pilates body

Key muscles used
Abdominal group, rectus abdominus and deep tranverse as well as internal and external obliques.

The look
The Pilates body is shapely and streamlined with an elegant upright posture, without looking stiff or muscle-bound. Pilates places no significant aerobic demands on the body, so there's often a softness to its shape, while the excellent posture the training develops makes it look lighter and more elegant.

According to Joseph Pilates, the founder of the exercise system, a person's true age is not measured by their years or how they feel but by the flexibility of their spine.

Pilates movements prioritise working abdominal core strength, spine mobility and correct alignment of the body, which allows efficient recruitment of different muscle groups (both in class and everyday life) without straining or creating tension in other parts of the body.

Pilates devotees can either practise the mat method or use a bench with pulley equipment, called reformers. While both methods focus on the same outcome, the use of equipment helps isolate specific body parts and can be more effective.

The footballer's body

Key muscles used
Mostly legs and torso but also arms and shoulders for goalkeepers.

The look
Among professional players, defenders tend to be the tallest and heaviest, whereas midfielders, who cover the most ground during matches are often shorter, lighter and more nimble.

Lower limb muscles, especially the quadriceps and hamstrings in the thighs used for powering kicks, are very well defined, while lean, strong torsos are essential for the balance and stability needed to sustain challenging tackles.

To catch speeding balls goalies also develop incredibly strong shoulders. Obviously, long arms and big hands never go amiss either.

· This article was amended on Monday July 7 2008. We said that, in Euro 2008, a ball kicked by the Croatian footballer Ivica Olic reached a speed of 31.76 kilometres per hour. In fact he was recorded running at that speed; a ball can travel much faster. This reference has been removed.