Recent research shows that short bursts of high-intensity exercise may be just as effective as longer, low-intensity workouts.
Recent research shows that the intensity of exercise, rather than its duration, is the key to physical fitness. Peta Bee explains the short and sweet approach It sounds like the perfect solution for a stressed-out, time-starved generation: gym sessions that can be completed in a matter of minutes and, proponents claim, with the same results as hours spent slogging away on the treadmill or exercise bike.
Many gym chains are embracing the concept of convenience or express exercise that can be slipped into your coffee break with time-reduced Pilates, yoga and circuit classes. Even the consumer watchdog the American Council on Exercise has billed "abbreviated fitness programmes" as the way forward for the millions who say they don't have time to stay fit. But can you really cut your workout time by half or even just one third and expect the same results? Leading experts think so. Research by the American College of Sports Medicine (ACSM) has shown that exercisers who plod away for lengthy periods on gym equipment often clock up "dead miles" and would be better off cutting the duration of their workout but increasing the amount of effort they put in. In their studies, physiologists at the ACSM have shown, for instance, that 30 minutes of high-intensity exercise (that's 80 per cent of your maximum aerobic capacity, a level at which you would be puffing and sweating) is as good as an hour at a workload of a much slower 60 per cent.
"You have two basic options if you want to get more fit," says Louise Sutton, the head of the Carnegie Centre for Sports Performance and Wellbeing at Leeds Metropolitan University. "Either you increase the time you spend working out considerably or you raise the intensity. For anyone who doesn't have hours to kill, a shorter, sharper session is more appealing and just as effective." In a typical express workout, the body is pushed outside its comfort zone with interval-style training - usually 30-second bursts of intense activity to raise the heart rate to 75 per cent of its maximum, followed by a short recovery period. "It is well documented among exercise physiologists that this sort of approach will get you fitter, faster," Sutton says. "Because you are working your heart and muscles so much more intensely than usual, it takes less time to reach the same fitness markers."
A 2005 study published in the Journal of Applied Physiology showed that after just two weeks of interval training, six of the eight subjects who took part doubled the amount of time they could ride a bicycle at moderate intensity before exhaustion. Eight volunteers in a control group, who did not do any interval training, showed no improvement in endurance levels. More recent research has also shown that the short but tough approach has other benefits, such as boosting the body's ability to burn fat. In another study published in the Journal of Applied Physiology, female subjects were asked to cycle for 10 sets of four minutes of hard riding followed by two minutes of rest. After two weeks of the interval training, the amount of fat they burned even during low-intensity exercise increased by 36 per cent, the researchers found.
Even resistance and weight training can be performed express style. A number of high-profile fitness experts in the US believe that strengthening sessions need to last only a little longer than the time it takes to heat a microwave meal. A 2004 study published in the Journal of Sports Medicine and Physical Fitness showed that short, intense weight training produced 50 per cent greater improvements in muscle tone than ordinary strength workouts.
Based on the unquestioned principle that muscle burns more calories, even at rest, than fat, the idea is to overload the muscles by using heavier weights but in a slow, controlled way so that they get stronger quickly. Instead of the usual four to five seconds it takes to lift and lower a weight at the gym, the new reduced approach requires that each repetition takes at least 10 seconds to complete. Some gyms have even installed loud, ticking metronomes to ensure clients accurately count the paces of each exercise.
The trainer Ken Hutchins, who advises the actor Brad Pitt, says a weight session needs to last no longer than eight to 20 minutes. Other trainers, such as Jorge Cruise, the author of the best-selling Eight Minutes in the Morning, and Adam Zickerman, a trainer who wrote Power of 10, agree that a mini-weights regime once a week is enough to tone flabby body parts. To those who raise a cynical eyebrow at such a suggestion, express weight training devotees point to a study published in the Journal of the American Medical Association in which researchers at the Harvard School of Public Health showed that men lowered their risk of heart attacks by 23 per cent through a weekly total of 30 minutes of weight training but by only 18 per cent through half an hour of power walking. Another study at the University of Glamorgan found that people who reduced the duration of their workouts by two thirds achieved the same strength gains through weight training, provided they increased the intensity of their workout.
Some personal trainers believe that workout times can be slashed even further - to as little as five minutes flat. Followers of the Tabata training principle complete exercise sessions that involve 20-second bursts of gut-busting effort followed by 10 seconds of rest. Each session lasts no more than five minutes. Named after the Japanese physiologist, Dr Izumi Tabata, who is widely credited with discovering the benefits of high-intensity exercise, the theory behind the Tabata approach is to push yourself to at least 85 per cent of your maximum capacity. The type of activity performed is not as important as the intensity and duration - the idea is to combine strength and aerobic exercise in each session. That might include cycling, running, kettlebells, weights and squat thrusts.
Research conducted on Tabata training several years ago showed that six weeks of the method lead to a 28 per cent increase in aerobic fitness. However, it is not an easy option and experts say you need to be fairly fit to try it. Dax Moy, a London-based personal trainer who has worked with many Hollywood stars, uses Tabata techniques with his clients but says that, ideally, it should be added once a week to enhance regular workouts and not as a replacement for ordinary fitness regimes.
"It's not something you should try if you are a beginner, as it can be very brutal," he says. "In theory, after a Tabata session is over you should feel as if you simply couldn't do another exercise. It should be that draining and exhausting." If there is a downside to other types of express workout, it is that you have to be prepared to do it regularly. Like any form of exercise, it does not promise a magic bullet to supreme athletic prowess and slender thighs.
"Any workout programme must have consistency in order for it to be successful and convenience workouts are no different," Sutton says. She recommends two to four 30-minute, gut-busting sessions a week for notable improvements. "To get more fit, you need to overload your body's system. You can shorten your workout considerably, but you can't shy away from effort altogether. Getting fit is always going to require hard work and a lot of sweat and toil."
Eight Minutes in the Morning by Jorge Cruise and Power of 10: The Once-a-Week Slow Motion Fitness Revolution by Adam Zickerman are published by HarperCollins. For general information about Tabata training, visit tabataprotocol.com.