Build your core muscles and you'll be amazed at how much stronger your arms and legs will become. Your core is the control centre of your body -- all movement that involves your arms, legs and torso, from walking to lifting to playing a sport, requires strength and stability in your core muscles. Strengthening them will make these activities easier, improve your posture and gait, and protect your muscles -especially in your lower back -- from strain and injury.

The core is a big area. It encompasses the 45 muscles in your shoulders, hips, abdomen and back. These muscles weaken over time and under specific conditions -- pregnancy, prolonged sitting at work and inactivity are all culprits -- but when they're strong, your posture, performance and stamina in just about any activity improve. A strong core will improve your ability to walk, jog or run, making you faster and less prone to fatigue. You'll also be able to bend, twist, squat, lunge, push or pull with greater ease and less risk of back pain and injury.

A bilateral lift -- sometimes called a "Superman" because you look like a superhero flying along the floor -- is a simple, effective strengthening exercise. It targets all the core muscles, and you're using the weight of your arms and legs to work against gravity, so you don't need any weights or equipment. If you already have a little bit of core control and strength, this lift will be a new challenge.

Bilateral Lift
1. Lie face down on the floor (or on a mat if you prefer a little cushioning) with your arms stretched over your head, just wider than shoulder-distance apart. Turn your palms in toward each other, thumbs pointing up at the ceiling. Stretch your legs along the floor, about hip-distance apart, and gently point your toes away so that the top of your feet are on the floor. (See full image.)

2. Squeeze your quadriceps (front thigh muscles) so your kneecaps come up off the floor. Pull your abdominals in without hunching your shoulders. Lift your chin off the floor, looking straight down at the floor.

3. Straighten and lift both arms and legs simultaneously until your feel a gentle stretch in your shoulders and hips. Hold the lift for a count of five, breathing slowly and deeply and pulling in your abdominals at the end of each exhalation.

4. Lower your arms and legs to the starting position. Repeat for the recommended number of repetitions.

Repetitions and sets
Do 10 to 15 repetitions, working up to two or three sets of repetitions, up to three times a week. For best results, align your head with your lifted arms. Don't lift your head and look at your arm as you lift; that throws off the alignment of your spine and might cause neck strain.

If you feel and tension or tightness in your shoulders, bend your elbows slightly. And remember, this exercise isn't about height and power but rather reaching for greater length and strength in your spine.