Watch a client grind out the last rep of a heavy squat or deadlift and you’ll often see it: jaw locked, teeth clamped together, face red. Most trainers coach bracing, breathing and bar path, but few think about what’s happening between the client’s teeth.
For clients who lift heavy several times a week for years, repeated clenching may contribute to jaw pain, headaches and worn or chipped teeth. You’re not expected to be a dentist, but you’re often the person who notices the signs first.
Why clients clench under heavy load
Clenching during a maximal effort is largely a reflex. When the body works close to its limit, muscles beyond the ones doing the lift tend to switch on too, and the jaw muscles are among them. Some research even suggests biting down can slightly increase force output, which is why some strength athletes clench on purpose.
A hard clench puts substantial force through the teeth. Repeated clenching may contribute to tooth wear or jaw discomfort, although the effects vary from person to person and aren’t determined by lifting alone.
Clients most likely to clench hard include:
- Powerlifters, Olympic lifters and anyone regularly working near their max
- Clients doing heavy compound lifts like squats, deadlifts and presses
- Clients who also clench or grind when stressed, or at night
What the research suggests
Research on lifting and dental health is limited, but one survey raises some interesting questions. A study of 602 bodybuilders and strength athletes published in the Swiss Dental Journal found that about a third reported problems with their mouth, teeth or jaw linked to training. Those who had been training for 10 years or more had about twice the odds of reporting problems.
The findings don’t prove that lifting caused these problems, but they suggest that jaw and dental symptoms during training are worth paying attention to.
Signs to watch for in your clients
You’ll rarely see the damage itself, but clients often mention the symptoms in passing. Listen for:
- Jaw soreness or tightness after training, or first thing in the morning
- Headaches around the temples after heavy sessions
- Clicking, popping or stiffness when opening the mouth
- Teeth that feel sensitive, or look chipped, flattened or shorter than they used to
- A partner telling them they grind their teeth at night
During sessions, you may notice a client clenching their jaw even during warm-ups or moderate sets. It’s worth asking whether they get jaw tension or pain after training.
What you can do as a trainer
Check whether they’re clenching on every rep. Some clients clench even when maximal effort isn’t needed. Encourage clients to relax their jaw between reps, particularly during warm-ups and moderate sets. They can maintain good bracing without clenching their teeth throughout the session.
Mention mouthguards, but don’t prescribe one. Some lifters choose to wear a mouthguard during heavy sets. Evidence that mouthguards improve strength is mixed, and it’s not yet clear how much they reduce the risk of long-term dental damage from lifting. If a client has jaw pain or chipped or worn teeth, suggest they see a dentist rather than assuming a mouthguard is the answer.
Know when to refer. If a client mentions ongoing jaw pain, recurring headaches or damaged teeth, suggest a dental assessment. Clenching during exercise can occur alongside clenching or grinding during sleep, so it’s worth mentioning both to the dentist. If night-time grinding is damaging their teeth, a dentist can assess whether a grinding guard is appropriate.
A small habit worth coaching
Clenching under heavy load is common, but it doesn’t need to happen on every rep. Help clients recognise when they’re holding unnecessary tension, ask about jaw pain and recommend a dental check if they have persistent symptoms. Small changes to their training habits may help protect their teeth over time.
About the author
Dr Steven Rostkier is a Melbourne dentist with more than 25 years of experience. A University of Melbourne graduate, he has run his own practice in Balwyn since 1999, providing general, cosmetic and restorative dentistry to families across Melbourne’s eastern suburbs.
