It also says that each gate you open causes progressively more damage to your body. Opening the first gate caused him to lose his speed after it wore off. And opening the 5th gate last time caused him to tear his muscles and completely exhausted him. He couldn't even stand afterwards. Thats all before Gaara crushed his arm and leg. He tries to crawl away from the sand but he can't because the Gates have pushed his body beyond it's limits.


While I can believe that maybe Gai is strong enough to do it while ignoring the fallout, having Lee uneffected was, plain and simple, another filler plothole.