Isometric thumb extension works the muscles that straighten your thumb, without the thumb actually moving. Sitting on a chair, you hold the tip of the thumb with your other hand and try to straighten it, while the other hand stops it from going anywhere. Physios often use holds like this when moving the thumb against resistance is still sore, or as a first step toward strengthening after a thumb or wrist injury.

How to do the isometric thumb extension

Sit upright on a chair with both feet flat on the floor. Bend your elbows and bring both hands up in front of you, a little above your lap, as in the video.
Turn the hand you are working palm up and let its thumb bend slightly. Place the fingers of your other hand over the tip of that thumb, pressing down on it.
Try to straighten the thumb against your other hand. The holding hand pushes back just enough that the thumb stays where it is.
Build up the effort gradually, hold it steady for a few seconds and keep breathing.
Ease off slowly, let both hands relax, then repeat.

What you should feel

Firm effort along the back of the thumb and up into the back of the forearm on the thumb side. There should be no sharp pain.

Common mistakes

Letting the thumb move, so it is no longer a hold. Match the two pushes.
Pushing with a sudden jerk instead of building the effort up.
Bending the wrist back to help the thumb push.
Holding your breath or lifting your shoulders while you push.

How often

A common starting point is 5 to 10 holds, each lasting 5 to 10 seconds, once or twice a day, with a gentle push at first. Your physio will adjust this for you, including how hard to press.

Stop and check with your physio if

Sharp pain in the thumb or along the thumb side of the wrist.
Tingling or numbness in the thumb or hand. If one side of your face or body suddenly goes numb or weak, or your speech becomes slurred or muddled, call emergency services, even if it goes away.
Thumb or wrist pain that is clearly worse later that day or the next morning.
Suddenly being unable to straighten the end of your thumb or lift it back, especially in the weeks after a wrist fracture. A thumb tendon can snap, so have a doctor check it within a few days.

From the clinic

The voice guide asks you to push as hard as you can. Here you start with a gentle push and build up over the following days, a more cautious start for a thumb that is sore or still recovering. Ask your physio before you work up to a full effort. If you have high blood pressure, breathe steadily through every hold and do not strain.

The tendons that straighten the thumb pass along the thumb side of the wrist. If that area is painful, as in de Quervain's tenosynovitis, or you have arthritis at the base of the thumb, check with your physio before pushing against resistance. After a broken wrist, hand or forearm, or surgery on any of them such as a tendon repair, start only when your doctor, surgeon, physio or hand therapist says the bone or repair is ready for this, and follow their plan for how much to do. For a similar hold at the wrist, see isometric wrist flexion.

Written and checked by the PocketPhysio editorial team. Last updated 2026-09-28.

This page is general education, not a diagnosis or a personal treatment plan. If you have pain, an injury or a health condition, see a physiotherapist or doctor before starting new exercises.

Isometric thumb extension