Lunges on the Ball -The Strong-n-Stable video series- Chek

[tnsandland]

It depends what phase of training somebody is at. MOST people are capable of progressing/adapting to complete that level of exercise (with the right trainer).

[jmonza]

do not do this exercise in the way that it is being shown in this video it is an easy way to injure yourself because it puts undue stress on the knee joint in order do these types of exercises one must be a highly trained genetically gifted athlete who has spent years doing this type of training.