Improve your flexibility by stretching. Stretch your hamstrings and buttocks by laying on your back with one leg crossed over the other at the knee. Pull the lower leg toward you firmly and steadily. This should stretch the hamstring of the crossed leg. For another exercise, touch your toes while seated, standing, with your legs spread, and with your legs crossed.
My son asked me to get book to help improve his jump and was thrilled with the terrific tips it gave him. According to him, this book covers all the important basics and is a must-read for anyone looking to increase their athletic performance. The exercises are described in a clear, easy to follow manner...and now that I've read it as well I'm happy to say, I understand more of what my son is always going on about! ;)
The simplest method to measure an athlete's vertical jump is to get the athlete to reach up against a flat wall, with a flat surface under his/her feet (such as a gym floor or concrete) and record the highest point he/she can reach flat-footed (the height of this point from the ground is referred to as "standing reach"); fingertips powdered with chalk can facilitate the determination of points touched on the wall. The athlete then makes an effort to jump up with the goal of touching the highest point on the wall that he or she can reach; the athlete can perform these jumps as many times as needed. The height of the highest point the athlete touches is recorded. The difference between this height and the standing reach is the athlete's vertical jump.