None at all! All drills done on real ice can be done on Extreme Glide Synthetic Ice. The small resistance factor helps with responsible technique (less cheating) and movement; our goalie partner centers have mentioned improved core and balance in their athletes after a few sessions on Extreme Glide. Our Synthetic Ice is ideal for goalies as it allows you to “keep your edge” and limits the skidding out that is often experienced on other formats of synthetic ice.