I've been using this method for a while, the pull up static and just bb curl static, when I started I noticed great gains after about a month or two.. I use this is combination with normal exercises (pull downs, curls, etc).. This is mostly done for size, not so much strength.. But with static you only notice a strength increase within 20 degrees up and down of the point you contract at, so a total of 40, which isn't bad.. But you're also weakening your GTO so you will notice strength increases in the full range of motion from that..