These exercises target your major lower body muscles. Keep in mind that as a runner, you don't want to overwork your legs, which get a workout every time you run.

Lunges

Stand with feet shoulder-width apart, a dumbbell in each hand in the overhand grip. Step out with your right leg about one stride, landing on your heel and rolling your foot down flat against the floor. Bend both knees so that your right thigh is parallel to the floor (do not let your right knee go beyond your right foot).

Your left thigh will be perpendicular to it, and your left heel will lift off the floor. Your arms remain by your sides during the exercise. Return to the starting position by rolling off the ball of your right foot. Alternate legs as you do your reps.

Start position for the Lunge

Finish position for the Lunge

Leg Extensions

Choose a chair with firm back support and in which, when you're sitting, your feet rest flat on the floor. Sitting in the chair, put the ankle weights on both feet. One leg at a time, squeeze with your thigh as you lift your leg until your knee is straight. Control the descent. This is 1 rep.

Leg Curls

Lie on the floor, with your arms at your side and the weights around your ankles. Turn your head to one side and lift both feet toward your buttocks, bringing your heels as close to your buttocks as you can. Use your abs to keep your hips pressing into the floor and lower your legs to the starting position for 1 rep.