A healthy back is as important to your running as fit legs. "If your back muscles aren't strong, they'll tend to fatigue faster, taking energy away from other muscles, and change your stride, which can lead to injury," says Lynn Millar, Ph.D., professor of physical therapy at Andrews University in Berrien Springs, Michigan. Here's a look at how each of your posterior muscles impacts your performance, and a few quick fixes that will help you run your best.
Key function: These muscles keep the body erect and help you rotate slightly with each running step, giving your hips and thighs more energy to push you forward. A weak lower back can put extra strain on the hamstrings, which can throw off your stride and cause injuries from the ankle to the hips, says Robert Gotlin, D.O., director of orthopedic and sports rehabilitation at Beth Israel Medical Center in New York.
Quick fix: Back extensions: Lie down, press your pelvis into the floor and lift your head, chest, shoulders, and arms. Hold for five seconds, repeat 10 times.
Key function: Strong shoulders keep your upper body relaxed, work with the arms to propel you forward, and help you breathe efficiently.
"Proper spinal alignment optimizes the function of the lungs and diaphragm," says Pilates instructor Rebekah Rotstein.
Quick fix: A Planks: Rest on elbows and hold for 20 to 60 seconds, five to 10 times. B Side Planks: Balance on forearm, hold 20 to 60 seconds, five times each side.