Exercises that straighten your leg at your hip and knee joints help increase stride length, loosen tight hamstrings and restore range of motion to an injured knee. They also increase hip and knee stability and mobility, according to physical therapist Gray Cook, author of "Athletic Body in Balance." When you perform leg-straightening exercises, start with simple routines that move one joint -- before complex exercises that move multiple joints.
Wall Straight Leg Stretch
This exercise uses gravity and support to help you increase leg extension without compensating with your spine. It also reduces stress on your lower back, which is ideal if you have back and hip pain, says fitness professional Anthony Carey, author of "Pain-Free Program." Lie on the ground on your back with your buttocks against a wall with your arms out to your sides. Put your legs up against the wall with your legs slightly apart. Push your tailbone toward the ground and point your feet toward your face. You should feel a stretch in the back of your legs. If you cannot fully straighten your leg but you feel a tight stretch, hold this position for one minute while taking deep breaths. Slide your heels up against the wall slightly as you hold this position to slowly increase the leg extension.
Wall Leg Lift
This exercise moves one leg up and down in a controlled manner while the opposite leg is propped up at 90 degrees against a side of a wall. Keep both legs straight throughout the exercise. Lie on your back on the ground and put your left buttock against the corner of a wall. Rest your right leg on the ground with your feet pointing toward your face. Raise your right leg up as high as you can until the leg position matches your left leg's position. Hold this position for three seconds and lower the leg at a rate of four seconds. Perform two sets of five to eight reps per leg.
Standing Toe Touch With Elevation
Put a half-foam roller on the ground and stand on top of it on the balls of your feet with your feet close together. Put a small firm cushion or yoga block between your inner thighs near your knee. Tighten your buttocks for balance and raise your arms above your head. Exhale and bend your torso forward to touch your feet with your fingers. If you cannot touch your feet, bend your knees as much as needed until you do. Hold this position for three deep breaths. Raise your body back to the starting position and repeat the exercise for five to 10 reps.
This yoga pose stretches not only your legs but also your posterior shoulders, back and buttocks together. Kneel on the ground on your hands and knees with your knees under your hip joints and your wrists under your shoulders. Lift your hip up and straighten your legs, pushing against the ground with your hands and your heels toward the ground. Bring your ribs closer to your knees as you hold this stretch for five to six deep breaths. Return to the starting position and repeat this stretch three more times.
Never stretch beyond your capability to straighten your legs. Stretching too much and too quickly can cause a stretch reflex, which is an involuntary contraction of your muscles and tendons to protect the joint and muscles from tearing, according to physical therapist Chris Frederick, author of "Stretch to Win." Always respect your limitations yet increase your flexibility gradually each day.