Will building my 'core strength' prevent injuries?

Alex Hutchinson draws on the latest research to answer your fitness and workout questions in this biweekly column on the science of sport.

THE QUESTION

Will building my "core strength" prevent injuries?

THE ANSWER

These days, it's all about the core.

Whether it's yoga, Pilates, exercise balls or myriad other fitness programs and gadgets, there's no greater selling point than a promise to improve your core stability.

And researchers now agree - for the most part - that weak core muscles can indeed be a key culprit in everything from lower back pain to sports injuries.

But here's where it gets sticky. "What people don't agree on," University of Calgary kinesiology professor Reed Ferber cautions, "is what the core is."

In particular, he says, there is a tendency to focus too much on the abdominal and lower back muscles and neglect the pelvic and hip muscles, which also play a crucial role in stabilizing the body during activity.

Dr. Ferber, who directs the university's running injury clinic, cites the example of a 40-year-old patient who came to him with knee pain. "She had a fantastic six-pack and did Pilates or yoga six days a week," he says.

But the woman was unable to complete a simple one-legged squat - bending at the knee while standing on one leg - because her hip muscles weren't strong enough to provide balance. This instability was the root cause of her knee injury.

The same pattern was borne out last year by a seven-month study of patients at Dr. Ferber's clinic, 92 per cent of whom turned out to have abnormally weak hip muscles. Eighty-nine per cent of the patients improved with four to six weeks of hip strengthening.

Similarly, a University of Delaware study of basketball and track athletes found that the best predictor of who would develop leg injuries during the season was weakness in one of the hip muscles.

Even among the abdominal muscles, not all exercises are created equal. A study presented at this year's American College of Sports Medicine annual meeting found that traditional crunches, which involve curling the torso up, mainly activate superficial "six-pack" muscles rather than the deep abdominal muscles that are more crucial for stability.

The study, by Auburn University researcher Michele Olson, used EMG electrodes to compare muscle activation produced by various core exercises. Pilates exercises such as the "hundred" and the "double leg stretch," in which the torso does not flex, were more effective than crunches at strengthening the deep abs.

For elite athletes, designing a core program often begins with a detailed assessment of their strengths and weaknesses in order to target areas for development.

But that remains more of an art than a science, Dr. Ferber says. Most people would benefit from a fairly general core program - one that includes an activity such as Pilates but also incorporates some more functional exercises that mimic the range of motion used in whatever activity they participate.

His top suggestion - based on the people he sees at his clinic - is hip exercises, which are relevant for sports ranging from soccer to cycling.

And working on the hips offers an important reminder, he adds: "The bottom line is a six-pack does not equal core stability."

Alex Hutchinson is a former member of Canada's long-distance running team and has a PhD in physics.

*****

It's all in the hips

Pelvic and hip muscles play a crucial role in stabilizing the body during activity, so they are part of the body's "core" and should be exercised along with the abdominal and lower back muscles.

HIP ABDUCTOR - STANDING

1. Place opposite foot behind the leg using resistance band.

2. Move band leg outward, keeping knee straight.

3. Count two seconds out and two seconds in, controlling the motion throughout.

HIP FLEXOR - STANDING

1. Place opposite foot beside leg with band.

2. Move involved leg forward, keeping knee straight or with slight "soft knee."

3. Count two seconds out and two seconds in, controlling the motion throughout.

HIP EXTERNAL ROTATOR - SEATED

1. In seated position, move leg outward and return to starting

position slowly.

2. Keep knees together.

3. Count two seconds out and two seconds in, controlling the motion throughout.

ROUTINE

Always perform these exercises after a workout. These are your key stabilizing muscles and if these exercises are done before a workout the risk of injury increases due to fatigue.

Progress up to three sets of 10 repetitions over a three- to four- day period to avoid muscle soreness. Gently stretch before and after. Several factors are related to a running injury. However, based on our research, you should perform these three exercises every day for the next six weeks to gain the necessary muscle strength to avoid injury and optimize your rehabilitation. Then, simply performing them two times a week thereafter will serve to maintain the strength you have gained.

SOURCE: DR. REED FARBER, UNIVERSITY OF CALGARY, RUNNING INJURY CLINIC