The majority of people who work out give their quads, calves, and hamstrings a stretch or two before and after a sweat session, but in order to really mobilize the hips & legs for optimal performance [as well as reducing the risk of injury], attention must be paid to the rest of the muscles in the legs/hips. Ancillary muscles that keep the legs in their proper path when running become tight and full of adhesions if they are paid no attention.
In particular the adductor muscles, which act to bring your legs in toward the midline of your body, are crucial in maintaining knee stability. In sports where lateral movement is present, such as basketball or ice skating, the adductors are a primary mover. In activities, such as running, where the body moves forward or backward, the adductors function as a stabilizer.
One of my favorite mobility exercises is a dynamic [moving] stretch that targets the adductors.
DYNAMIC ADDUCTOR STRETCH:
STEP 1: Get into a quadruped position, with your shoulders directly over your wrists, and your knees directly under your hips. Once in this position, extend the left leg all the way out to the side, so that your toes are pointing directly straight ahead. Tuck the toes of your right foot underneath, as if to do a pushup.
STEP 2: Keep your hands flat on the ground, and keep your back flat, while lowering your butt down toward your heel. As you do so, fully exhale through your mouth. You will feel a stretch in the inner part of the left leg.
STEP 3: Return to the start position, and repeat all repetitions on the left leg. Then return to quadruped position, extend the right leg, and complete all repetitions.
This exercise is most effective when done as part of a warm-up. Be sure to keep this a dynamic, or moving, stretch. In this case, complete 10-15 repetitions per side.
***You may also do a static [stretch and hold] version of this exercise at the end of a run or workout. Simply hold the stretch at the bottom for 20-30 seconds on each side.***