What is better for bench - a thumb over or thumb under grip?

From a biomechanical standpoint the thumb under or traditional grip is more advantageous. It increases grip, and activates more muscles in the arms, chest and shoulder region. Furthermore, the traditional grip is better from a safety stand point, having your thumbs wrapped around the bar decreases the risk of an injury from the bar slipping and falling during a lift. A thumbs over or "suicide grip" is popular among bodybuilders because it increases utilization of the chest muscles instead of the forearms and shoulder, and for some athletes is more comfortable. The biggest concern with the thumb over grip is the safety issue involved with it. Without your thumbs in place, the risk of the bar rolling off your hand and allowing the bar to land on your chest, face or neck increases dramatically. In IPF sanctioned meets you are required to do a bench press with the traditional thumbs under grip, so if you plan on competing, you should be comfortable with that method. Regardless of which grip you go with, always use a spotter for anything beyond warm up sets.

Some people prefer one, some people prefer the other. I have not read anything that provides conclusive evidence for one of these grips having an advantage over the other. I can say however, that the thumb under grip is dangerous. They don't call this the suicide grip for nothing! I am sure most of you have heart about the college running back, Stafon Johnson, who was bench pressing using the thumb under grip when the bar slipped off his palms and landed on his neck nearly killing him. This is testament to the fact that this grip is dangerous because this individual was not new to bench pressing. I am sure over the course of his life he has performed thousands and thousands of repetitions without incident. But it only takes one mistake to cause an injury that can change your life. Additionally, I found that when I used to bench press with the thumb under grip (I am a thumb over guy now) that it would put excessive pressure on my wrist, causing trauma to the joint. I have scar tissue built up at the base of the thumb where it joins the wrist. So in my opinion, stick to a thumb over grip when benching!