Abdominals
A strong midsection supports a runner's torso to help maintain good form. It also limits extraneous side-to-side movements, which sap energy. While there are almost as many ab exercises as there are runners, there are only three moves necessary to build a strong, stabilizing system. Do two sets of 10 reps per exercise.

Upper Abs
Lie on your back, knees bent. Lock your feet under a heavy object. Fold your hands across your chest; tuck your chin. Roll up until you are upright. Hold for a second; roll down slowly.

Oblique Abs
This time, interlace your hands behind your head. Twist your torso to one side. Roll up slowly, leading with the elbow. Hold and then, still in rotation, roll slowly down. Alternate sides.

Lower Abs
Lie with knees bent, ankles together. Reach overhead; hold onto a heavy object. Bring your knees to your chest. Lift your knees toward the ceiling until you're up as far as you can go. Lower.

A NEW TRAINING MODEL
Building tough, durable runners from the ground up.

The Wharton Performance Model, a training approach that improves performance and prevents injuries, is grounded on a foundation of flexibility and strength. Once this baseline is set, you can add the additional levels: cardiovascular endurance, sport-specific strength, skill development, mental preparation, and competition. (Rest, nutrition, and hydration are integral at every level.) If you were to create a pyramid based on your current plan, chances are your model would topple over. Most training plans skip the flexibility and strength phases--and this leads to injury. For example, a runner who jumps into speedwork or long runs before establishing a solid foundation won't be able to withstand the stress of the increased intensity or mileage. To prevent injuries, we recommend that runners adopt a daily flexibility plan (including range-of-motion exercises pre- and postrun) as well as a strength-training routine three times a week