Robbie Cole is offering a great leg strengthening exercise in the video below. Robbie, a Muay Thai instructor shares one of his favorite exercises. I have done this drill and love it. If you are suffering from a bad lower back you should remove the jumping portion of this exercise. Other important safety tips include:
1. Watching the angle of your knee joint so that it maintains a right angle.
2. On the side lunge, keep the length of your stride manageable.
3. Avoid hinging forward on all of the exercises.
4. If you find this to be a challenging drill, go slowly. It can be a straight strength drill and build into a power drill as you become stronger.
5. Try 30 then 60 second rounds. The number of reps and speed is less important at the beginning.
6. Warm up and include inner thigh stretches to avoid injury.
7. You do not need to begin with a weighted ball, this exercise is amazing without weight.
8. Make sure you breath through the entire exercise and integrate an exhale on the plyo or jump portion of the series.
9. The plyo jump can be a standard squat jump if you want to avoid the deep flexion of the knees.
10. Make sure you take rests in-between the rounds.