This exercise is easy on joints, but hard on calories

In the water, you exercise with only a fraction of your own body weight, making it easier on your joints, but with more resistance than on land, making it harder on calories. — dpa

It's relatively cheap to do, great for both beginners and athletes, works all year round and has very low risk of injury.

And you’ll even burn more calories than on land.

A popular form of cross-training and rehabilitation among top athletes, aquajogging is low-impact resistance training in which you move your arms and legs in a running motion in a pool.

This can be either in shallow water with your feet touching the bottom, or in the deep end.

The former usually isn’t practicable as you’ll likely have to weave your way through a horde of kids.

Most people aquajog in the deep end of the pool, and although your feet don’t have contact with the bottom, you should make slow forward progress.

All you really need in the way of equipment for deep-end aquajogging is a flotation belt – it helps you to keep the correct upright posture.

As an alternative, you can use foam ankle cuffs for more buoyancy.

The sequence of movements is simple.

“Imagine you’re running outside, only the movements are slower and more concentrated,” says German running coach and 2006 European champion over 10,000m Jan Fitschen.

It’s important to remain upright and not let yourself lean forward.

Variations are fine – you could jog in a lane with your legs straight, or with faster or slower movements, perhaps interspersed with a round of water aerobics or a lane of high-knee jogging.

“In the beginning, you can alternate jogging in water with swimming,” he suggests.

While aquajogging requires “little instruction and hardly any equipment”, as Fitschen notes, it’s quite taxing.

“Running through water is much more strenuous than running on land, because the resistance of the water is about 800 times greater than that of air,” says German Society for Sport Medicine and Prevention (DGSP) general secretary Dr Ruediger Reer.

According to the University of Hamburg sport and kinetic medicine director, a half-hour of aquajogging burns approximately 400 calories, compared with about 300 when you jog on land.

Water buoyancy reduces weight-bearing to just 10% of your body weight when you’re immersed up to the neck, “so being overweight only plays about 10% of a role,” he points out.

“That’s gentle on joints and tendons.”

At the same time, aquajogging builds both strength and endurance by not only working out your legs, but also your arms, shoulders and back.

Nevertheless, as a precaution against osteoporosis, you should also work out on land, where high-impact weight-bearing exercises help build bones and keep them strong.

There are just a few medical reasons not to aquajog.

They include a recent heart attack, a neurological disorder and an acute disc herniation, says Dr Reer, adding: “When in doubt, consult your doctor first, of course.”

And it’s not just for recreational athletes.

“I don’t know any competitive athletes who haven’t aquajogged at some time,” remarks Fitschen, who says many like to tag on a round of aquajogging after an outdoor running workout – a regenerative measure as it were.

“The water pressure acts as a kind of massage, relaxing tensed muscles,” he explains.

This all sounds great, but a danger lurks in aquajogging – namely, taking it too easy.

“The water offers only as much resistance as the effort you exert,” he says.

So if you unwittingly slow down your pace, your workout will be less effective. – dpa