The most recent development in exercise footwear, toning shoes which give a free lower body workout just by walking around, are proving to be a big hit with consumers everywhere. Sales figures have grown exponentially over the last two years or so, and the sales volume for 2010 is forecast to be somewhere in the range of $ 1 and $ 1.5 billion when the full results become available.

Toning shoes vary in design from one manufacturer to another – but the basic principle is that they use a specially designed sole which introduces instability during the walking process. This makes the muscles in the lower body work a little more than normal as they strive to regain the body’s balance. That’s how the toning and trimming effect is achieved.

The major toning shoe firms – Skechers, Reebok, Masai Barefoot Technology and FitFlops – have all carried out or commissioned studies to verify the effectiveness of their products. However, some query the validity of the results given that the studies were funded by the footwear manufacturers.

User based feedback and testimonials seem to be very positive on the whole. There is no shortage of glowing reviews from satisfied users. It’s noteworthy that a high percentage of satisfied customers advise of benefits which aren’t actually claimed by the footwear manufacturers. Relief from foot pain, joint pain, or both, is a commonly reported benefit.

Perhaps it shouldn’t be so surprising. After all, Swiss engineer Karl Muller originally developed MBT shoes in order to reduce lower back pain after he found that barefoot walking across a Korean rice field helped to minimise his own perennial bach ache.

After some further research, he learned that the Masai tribesmen of Africa have a much lower incidence of back pain than westerners and that they are also noted for their excellent posture. He went on to develop MBT shoes which, thanks to their specially engineered sole, replicate the sensation of walking barefoot over soft ground.

FitFlop wearers are every bit as likely to wax lyrical about the great fit and extreme comfort of their FitFlops as they are to mention any perceived toning benefits. On the face of it, for a lot of wearers, any potential toning effect seems to be viewed more as a bonus than the main function of these shoes.

The fact that the most recent Fit Flops release is a clog aimed specifically at hospital workers, doctors, nurses and other shift workers who spend lengthy periods of time on their feet throughout the course of their working day/night is significant. The fact that the toning sole’s design, in addition to the much hyped toning and trimming benefits, helps to distribute the weight more uniformly over the sole of the foot is the thing that increases the comfort.

FitFlop founder Marcia Kilgore has, according to the company website, been petitioned by hospital workers and other shift workers in planes, elevators and grocery stores to launch a shoe for people who spend a long time on their feet during the course of their working day. Which would explain the appearance (in the UK only, for the time being at least) of the new FitFlop Gogh Pro – a clog which is very similar to the existing ones in the FitFlop range but which incorporates a new pivoting heel strap for a secure fit and features a no-slip, no-marking sole.