Strengthening your jaw to hold it in place during contact sports is a good thing. Being able to hold strong isometric contractions during an impact not only protects the jaw, but lowers the subconcussive forces associated with head injury.
The lateral pterygoid, anterior belly of the digastric, geniohyoid and platysma muscles are involved in jaw opening. The anterior portion, the thickest part of the platysma muscle depresses the mandible when you strain during effort leaving the mouth partially open. When you tuck your chin the powerful masseter muscles on the side of your jaw are neurally inhibited. The masseter muscle is a jaw closer, this means it is important to maximize openers, as well as, closers to hold the jaw in place since neural inhibition can reduce the number of muscles involved in a particular head movement.
Jake Cox played football at Kansas and has a masters degree in Kinesiology from Stephen F. Austin. Jake is the Head Strength and Conditioning Coach for the Villanova University football team. Coach Cox runs a comprehensive head and neck program that includes exercise for the jaw. He trains his athletes utilizing 6 Pendulum 5-Way Head and Neck Machines, Manual Resistance and Resistance Bands. The Villanova Wildcats protect their athletes by Getting them Strong.