Graeme Marsh, a personal training manager for Virgin Active, said clocking up hours on the treadmill or cross trainer could become worthless over time unless people mix-up their routine.
Canadian researchers recently found that the body could get as much benefit from short intense bursts of exercise lasting ten minutes as from ten hours of moderate training.
"If your training on the treadmill is always eight miles per hour for 45 minutes then you are going to see diminishing returns very quickly. Over time you will get less and less from it in terms of fitness improvements," the Scotsman quoted Marsh as saying.
"There's a saying in the industry that if you keep doing what you're doing you're going to keep getting what you get. So, if you go to the gym and always do the same routine, you are not going to see amazing results," Marsh added.
Marsh said interval training such as that trialled in the Canadian experiment could help people get quicker results and improve their fitness.
The training expert suggested people work out at a high intensity - at eight or nine out of ten - for up to a minute, before easing off and recovering for two to four minutes.
They should progress either through doing harder intervals of intense training or through taking shorter recovery intervals.
"The theory behind interval training is that by working at higher intensity you increase your metabolic 'engine' and favourably change your physiology. Research has shown that with higher intensity training you get changes in enzymes and hormones that favour fat burning," Marsh said. (ANI)