TMJ or Temporomandibular joints implies the jaw joints (we have two joints which work simultaneously for eating, speech, swallowing, yawning etc. TMD or Temporomandibular (joint) disorders is disorder affecting the jaw joint or jaw muscles and the symptoms range from jaw pain, jaw sounds, jaw locking, headaches, etc.
What is the relation between teeth clenching and exercise?
Some people do clench their teeth while exercising (mainly strength training) but there is no good studies to show if there is any clear relationship between them. Actually, some people who clench find that their jaws relax during or after exercises (including lifting weights). Teeth clenching involves gritting of the teeth due to severe tension in the jaw muscles. While muscle tension in the jaw area is common during exercising, they are usually not symptomatic and do not require an intervention.