Would you like to improve your latest 5K run time without doing an extra session of track workout? Do you want to cruise up Emerald on your mountain bike with power in your pedals? If so, consider core training.

What is "the core?"

The core refers to the muscles that attach to the spine, shoulder girdle and pelvis that provide the necessary stability to hold your body upright with good posture. The core is the link between the upper and lower body. It provides the transfer of energy between the two halves. Core muscles include abdominals, hip flexors and rotators, gluteals, shoulder and back muscles.

What does it mean to have a strong core?

Core strength can be defined as the ability to achieve and maintain alignment of the middle of the body during movement in order to enhance the efficiency of limbs farther from the middle.

It's basic physics. The musculoskeletal system works as an arrangement of levers. The fulcrums of these levers must be stabilized by muscle for proper force generation. This means that if you have a stable core foundation, the arms and legs are stronger.

How will it help your

running and biking?

If you think about running, it is actually the act of falling forward and catching yourself with each step. In terms of stability you are asking your muscles to stabilize the body over a single, narrow point of contact (the foot) approximately 150 times per minute. It's no wonder that as core strength decreases, running form gets sloppy.

During biking, strong abdominal muscles transfer power from handlebars to pedals during uphill climbs. The core controls the small movement adjustments necessary to maintain balance during technical descents.

Injury avoidance is another benefit of core training. For example, knee pain is something that is common to bikers, runners, and many other athletes. Many forms of knee pain are the result of poor alignment of the knee over the foot during a running stride or pedal stroke. Strengthening the muscles of the hip and buttocks can help maintain this proper alignment and reduce stress on the knee joint.

When should you do core training?

Core training should be a complement to your exercise program. It should be included in all phases of training -- base, build, taper and peak. A 10- to 15-minute aerobic warm-up of walking, jogging or biking should be performed prior to doing a core workout.

Exercises should start easily and slowly with the focus on form and breathing. Many people make the mistake of doing exercises that are too difficult for their current strength level at the expense of good form. This not only reinforces poor muscle substitution patterns but can also contribute to injury.

Core strength exercises come in many flavors -- Pilates, yoga, or less traditional methods (think Bode Miller doing crunches while hanging from the rafters). Pick the form that you enjoy and find challenging and get to it. You might just find that extra spring in your step or power in your pedal with a lot less effort.

Jen Kerr, DPT, is a physical therapist at SportsMed at the Justin DeSorrento Sports Medicine Center at Yampa Valley Medical Center.