Clenching your teeth in the middle of a heavy set is a natural reaction to an intense activity. Unfortunately, not only does such straining look sort of silly, but research also has shown that it actually makes you weaker and less powerful, which doesn’t exactly come in handy when you’re squatting twice your bodyweight or more. One solution: the ArmourBite mouthpiece by Bite Tech, a cutting-edge company that specializes in athletic enhancement and safety. The ArmourBite places its patented “Power Wedges” between your molars to retain optimal spacing between the bones of the jaw and skull, opens airways and essentially makes that jaw clenching work for you. Recent studies have shown that using the device can enhance strength by 20 percent, endurance up to 25 percent and can significantly lower levels of the muscle-wasting hormone cortisol, as well. $30; BiteTech.com.