The two products, which cost thousands of dollars each, have recently become popular in Hong Kong.

A council spokesman said experts from the Hong Kong Physiotherapy Association and the Hong Kong Orthopaedic Association believed the effectiveness of the horse-riding machine was only equivalent to ?mild aerobic exercise?.

He said its effectiveness would depend on the speed, intensity and frequency of use.

The horse-riding machines are designed to enhance functions of the heart and lungs ? as with other forms of aerobic exercise. Although regular aerobic exercise could help the body burn calories, the council concluded the horse-riding machine was not suitable for some people.

The council said it was particularly concerned about the elderly, very young people, and people with spine or muscular problems using it.

?They should seek medical advice before adopting any physical exercise,? the spokesman warned.

The council also said the slimming belts were not very effective for achieving weight loss.

?This is because the belts provide only passive exercises in which their effect in burning excess body fat is none or minimal,? the spokesman explained.

He warned that oscillating movement brought about by the belt might cause skin itchiness or soreness.

?People who are pregnant, taking long-term medications, suffering from tumour/heart diseases/back disorders, or feeling unwell after use, should seek medical advice before adopting this exercise,? he said.

The spokesman said maintaining a balanced diet and exercising were the most effective ways to lose weight.