Like diets and cocktails, a new gym fad comes around every few months. Some, like step and Pilates, prove their worth and become long-term fixtures. Others disappear quicker than you can say karaoke spin. If you've been inside a gym lately, you may have noticed people balancing on what look like giant beach balls. They have various names - Swiss Balls, Fit-balls or Physio balls. Or perhaps you have friends who have started boasting about their core training.
Core training isn't a recent invention, it has been used for years by physiotherapists. "Personal trainers have caught on to the idea of thinking of the body as a unit, so instead of just training the shoulders or the legs, they train it as a whole, and for that to work, the base has to be strong," says Hayden Rhodes, training instructor at the Third Space gym in London.
"Core stability is the correct use and control of your deep stabilising muscles," explains physiotherapist Chris Boynes, "the little muscles that run up the spine - the transverse abdominals and the gluteal muscles. It's your trunk and your deep stabilisers at the bottom of the spine and pelvis, the lumbosacral muscles. It's muscle groups, integrating and tightening, giving more stability to the spine and trunk region."
Most of us only use, at best, 60% of our muscles in the core area, hence poor posture and common back problems. So we need to re-educate our bodies. You use core muscles to sit, stand and lift objects; improving them is about functional fitness, something that benefits you every day, rather than how good you look in the mirror. The sudden popularity of core training is due to a change in gym-goers' mentality. "People are realising that there's more to being healthy than avoiding cigarettes and getting enough calcium," says Rhodes.
The aim is to locate those dormant muscles and learn how to use them. It's a motor skill that enhances body symmetry and muscle balance. "It's training from the inside out," says Reebok master trainer Lorna Malcolm. "Over time, you develop a strength within and you'll see an improvement in posture and alignment."
The core board, used in the Reebok classes, is an egg-shaped wobble board, around 3ft by 2ft, with three legs. The board twists and tilts when you put weight on it. It's like a combination of a basic aerobics/toning class plus circuit training, but without the choreography or weights. "You can do virtually any exercise on the board: press-ups, sit-ups, squats, lunges," says Malcolm. "The fact that it is unstable means that you must balance and stabilise, or you'll fall off, so when you're on the board you are constantly using those muscles; it's something that happens immediately, without you thinking about it."
If it sounds easy, try standing on one leg - you'll notice that you can't help but engage your core muscles. Now add some hand weights and you'll see the difference that adding the challenge of balance makes. This is where the balls come in. Sit-ups and squats are hard enough, but try doing them on an oversized space hopper and you'll soon rediscover those long-forgotten muscles.