THE BATTLE OF the bulge is on-going for Katrina Maple. She says she has always fought extra weight on her bottom, hips and thighs. Twice a week, Maple puffs her way up the 1,500 stairs that lead to the summit of the Twins, the towering hills behind Repulse Bay. She supplements this with a weekly visit to the gym, where she uses the stationary bike and stair-master for up to an hour each time. 'I'm a classic pear shape, so I concentrate on working out these areas to lose weight and gain definition,' she says. 'My fitness and strength have definitely improved, but as yet I haven't noticed a huge difference in the shape of my thighs.' In a recent article in Britain's Sunday Times magazine, celebrity personal trainer Matt Roberts - who counts Sting, Naomi Campbell and Tom Ford among his clients - says the last thing a pear shape like Maple should be doing is concentrating on her thighs and bottom. Instead, Roberts says, pear-shaped people need to develop shoulder width and depth of chest to balance their upper and lower halves. To burn fat on hips, bottom and thighs, he suggests so-called pears follow a moderate aerobic workout for at least 30 minutes, three times a week, and avoid exercise with heavy weights aimed at the problem areas. In other words, it's all about exercising the right way for your body shape. But not everyone's convinced. 'Body shape is genetically determined,' says Wong Heung-sang, of the Department of Sports Science and Physical Education at the Chinese University of Hong Kong. 'We can modify it, but we can't change it. If you don't exercise and have a poor diet, your shape will be affected.' But Wong disagrees that exercising for your specific body shape will make a difference. He says research should be taken into account when discussing exercise and body shape. 'What many experts - perhaps without the right professional qualifications and experience - describe about the different body shapes can be found in any sports science or human physiology textbook - it's nothing new,' he says. Wong says he's dubious about exercising for different body-types. 'They're publishing articles and writing books, citing so-called evidence to support their claims. But in peer-reviewed journals or scientific publications, these claims are viewed with scepticism.' Roberts - who is also a one-man fitness centre and publishing entrepreneur - says women fall into four body types: the apple (with most weight carried around the stomach area), the pear (bottom heavy - especially buttocks, hips and thighs), the tube (pretty much straight up and down) and the hourglass (cinched waist, with curvaceous chest and buttocks). Although he admits that it's virtually impossible to change your shape, the trick is to create the illusion of a different silhouette. This may sound like bad news, but it should ease the pressure many people feel to achieve a body shape they're not designed for, he says in the Sunday Times magazine. Look on the internet or in fitness magazines and you'll find a host of experts who have jumped on the body-shape bandwagon. Many, like Roberts, have created their own range of categories based on the human physiology textbook definitions of body shape: ectomorph (long, wiry and narrow); endomorph (soft, curvy and often pear-shaped, tends to hold on to fat more tenaciously); and mesomorph (bigger bones, and tend to develop muscle easily). Many men and women are a combination of categories. But Wong says it may be just hype. 'Most people can follow the same regimen irrespective of their body-shape blueprint,' he says. 'According to recommendations from different professional and medical organisations, doing aerobic exercises most days of the week for 30 minutes is useful to maintain overall health. This would be applicable to most people. A combination of a balanced diet and physical activity is the most effective method to control or maintain body weight over the long term. If you actively want to manage your weight, you should increase the duration of the exercise to 45 to 60 minutes.' Wong says the type and intensity of the exercise also has an effect. 'Aerobic exercise helps to burn fat and reduce fat stores from different sites over the body. At the same time, you should work out or weight train each week to strengthen muscles. When muscle tone is improved body shape will improve.' Hong Kong personal trainer Errol Samuels strongly recommends tailored exercise programmes but doesn't advise exercises solely for body parts you want to change. 'It's important to choose the right exercise,' Samuels says. 'You can have two people weighing the same and with the same amount of body fat, but it doesn't mean they're equally fit. It's not about the way you look, it's your body fat levels. 'For a woman, up to 20 per cent body fat is fine, but anywhere towards 30 or 40 per cent is considered obese.' Despite their different body shapes, Chinese and western people often carry the same amount of fat, he says. However, fitness experts Liz Neporent and Gina Allchin of ivillage.com go along with Roberts' views about specific exercise. For example, they recommend that female ectomorphs such as Kylie Minogue concentrate on building up muscle with weight training. They advise using moderate to heavy weights that can be lifted for six to 10 repetitions and a split routine, whereby you work some parts of the body one day and others the next. As well, they recommend moderate to intense cardio exercise three to five times a week for 20 to 40 minutes per session. Endomorphs such as Liz Hurley or Jennifer Lopez should emphasise their curves by adding muscle tone. Perform a total-body weight-training routine three times a week using high repetitions and moderate to light weights, and do 30 to 60 minutes of moderate cardio three to six times a week for maximum fat and calorie burn. Mesomorphs such as Madonna and Jerry Hall should do light to moderate weight training two to three times a week to enhance tone, not size, and three to five cardio workouts a week at a moderate to fast pace. Hong Kong-based personal trainer Johnnie Guy says genetics play a key role in body shape. 'Genetics have given you a certain shape and that's the way it's going to be. You should take a photo of yourself aged 18 in a bathing suit or something similar, so your trainer can see what your body shape is, and what you hope to achieve.'