"Wall work" - Bad for knees?

[BSheehan]

Tom,

Our dojo has us doing "wall work" where the students put one hand on a wall, then tuck up in a roundhouse kick position, and then fire out a large number of roundhouse kicks with the intention of building endurance in the leg muscles.

I am concerned as to whether this type of exercise is healthy for the knees, since I suspect that once the leg muscles tire, the knee joint will lose its supporting muscle which in turn will likely put damaging stress on the knees.

Additionally, I have not seen this form of leg exercise being promoted elsewhere, and I suspect that the potential knee damage is the reason why.

I welcome your thoughts.

Thanks,
B