A proper warm-up is crucial for preparation before any extreme stretching, especially a side split, which is also called a straddle, to avoid pulled or strained muscles. If you have never done an extreme stretch before, do not attempt to accomplish your desired results within a day, week or possibly even for several months. Your body's natural structure can also limit your capability to accomplish this goal. Think of this training as a gradual process to improve your body, rather than a goal to obtain a static position.
Prepare and Train Your Muscles
Warm up your back and hips. Sitting on the ground, bend and open your knees to the side so that the soles of your feet are touching in the butterfly stretch. Bring your feet in toward you until you feel a gentle stretch. Your back and hip flexibility determine how close you can bring your feet in.
Curve the top of your head toward your feet. Use your elbows to push your knees down closer to the ground for a more intense stretch, if desired. Hold the pose for 30 seconds, and repeat this up to two times successively, or up to three times within a training session.
Activate and further stretch the inner thigh muscles, which are also called adductor muscles. Start in a wide standing position, and place your toes pointing slightly out from your heels -- just enough to maintain your balance. Bend one leg at a time in this side lunge, and focus on stretching the muscles on the inside of your legs. Hold here for 30 seconds and repeat on the other side, up to two times per training session.
Increase your stretch by lowering your body closer to the ground into an extreme side lunge, but only after the previous stretch does not impose pain or an intense stretching feeling. Keep your heel on the ground and your knee in line with your toes, instead of torqueing your knee to one side or the other. Hold for 30 seconds and repeat on the other side, up to two times per training session.
Progressive Side Split Training
Sit on the floor with your legs in front of you and your knees straight. Separate your legs until your feet are slightly wider than your shoulders, which places your body into a side split stretch. Hold this position for 30 seconds, and repeat up to three times per training session. Continue this process every day until there is no longer a severe stretch in your groin and back area.
Pull yourself toward your legs or feet, if possible, to gently and slowly create a more intense stretch.
Progressively widen your legs after there is no longer an intense stretch in the previous leg distance. Keep your knees pointing toward the ceiling. Once your legs form a 180-degree angle, or a straight line from foot to foot, you have completed a side split. Hold the split for 30 seconds, and repeat up to three times per training session.
Continue this series of stretches until the desired flexibility is reached. Periodically repeat this stretching process (such as once every two to five days) to maintain flexibility and to avoid injuries that accompany spontaneous attempts to perform side splits.