Your anatomic center, or core, generates strength and mobility for the whole body. The core muscles provide endurance for holding a position and dynamic power when the body is in motion. A strong core equips you to handle the routine physical demands of daily life – lifting children, working at a desk, doing housework, driving a car, or simply getting up out of a chair – with greater ease and comfort.

When training your core, less is more! For optimal results in minimal time, pick the most effective exercises that engage multiple muscles simultaneously in an integrated fashion. Instead of repeating numerous sets of the same exercise, focus on targeting all the muscles that encircle the torso for a well-rounded core workout. These are four of the best exercises.

1) Bicycle Crunch: Studies show that this is the single most effective type of crunch. The bicycle crunch engages the rectus abdominis (the coveted "six pack" muscle) to flex the spine as well as the internal and external obliques to twist the torso.

Proper form for Bicycle Crunch: Lie on your back with your knees bent over your hips, calves parallel to the floor. Rest your head lightly on your fingertips. Tighten your abs and lift your head and shoulders off the floor, twisting one shoulder to the opposite knee, as you extend the other leg toward the floor. Alternate sides for 20 repetitions (one rep = both sides).

2) Plank: The rectus abdominis and obliques team up again, this time in an exercise which does not require you to curve the spine forward. Instead of doing endless crunches, try this abdominal stabilization exercise where you hold your trunk in perfect neutral spinal alignment, "hovering" above the floor.

Proper form for Plank: Lying on your stomach, position elbows directly beneath the shoulders, forearms on floor. Come up onto your toes and lift your body off the floor, creating a straight line from shoulder to knee. Pull your abs tight and anchor your shoulder blades. Hold for 30-60 seconds.

3) "Dead Bug": In this exercise, the obliques work with the deepest abdominal muscle, the transverse abdominis, to hold the pelvis in neutral position while the moving limbs provide resistance. Be careful not to arch your lower back or rock your pelvis from side to side!

Proper form for "Dead Bug": Lie on your back with your knees bent over your hips, calves parallel to the floor; both arms extended to the ceiling, palms forward. Pull your abs in tight, belly button to spine. Lower an opposite arm and leg toward the floor, lengthening through the limbs, and bring the other knee in over your chest. Switch sides for 10 repetitions (1 rep = both sides)

4) Opposite Arm/Leg Lift: To balance out the abdominal work, this exercise targets the deep muscles along the spine, the erector spinae, as well as the glutes in the buttocks and the deltoid in the shoulder. As a bonus, it challenges your balance and stabilization.

Proper form for Opposite Arm/Leg Lift: Kneel on all fours, wrists beneath shoulders, knees under hips. Lift one leg to the back, keeping the knee straight, then reach forward with the opposite arm, palm facing in. Do 3 repetitions, holding each side for 10 seconds (1 repetition = both sides)

Mastering these exercises gives you a well-structured core workout. Multi-tasking your muscle groups saves time and improves your ability to function in your daily activities. Remember to do your abs routines on non-consecutive days to allow the muscles to rest and rebuild.

For expert guidance on strength training techniques, step by step photos depicting how to perform the exercises and a selection of well-rounded workouts please check out the book Strength Training Exercises for Women by Joan Pagano at http://bit.ly/JPFSTEW

Joan also offers an online fitness and nutrition course, “Beat Belly Fat, Bloating, Bone Loss and the Blues” available on her website here.

4 Key Core Moves to Firm Your Torso and Flatten Your Belly