Three things make a grip weak, and they are not interchangeable.
- PAIN stops you squeezing.
- A NERVE stops the message arriving.
- A TENDON means the rope is no longer attached to the thing it pulls.
The fastest way to tell them apart is to ask whether it hurts.
Weakness without pain is the one to take seriously, not the one to ignore.
Pain-limited weakness
The muscle works. You just stop it, because squeezing hurts.
Test it on yourself: grip something gently and it feels fine, grip harder and pain arrives before the limit of your strength. That is inhibition, not weakness.
Common sources are
Grip strength typically returns once the painful structure settles, without any specific strengthening at all.
This is why measuring grip on day one and again at week six is worth more than any amount of describing it. Numbers move even when the story stays the same.
Nerve weakness
Painless, specific, and it follows a map rather than a mood.
Each nerve supplies particular muscles, so the pattern of what fails tells you where the problem is.
- Ulnar nerve. Weak pinch, difficulty crossing the fingers, fingers starting to claw, hollow spaces between the bones on the back of the hand. See cubital tunnel and Guyon’s canal
- Median nerve. Weak thumb, difficulty lifting the thumb up away from the palm, flattening of the muscle bulk at the thumb base. See carpal tunnel
- Radial nerve. The wrist drops. You cannot lift the hand at the wrist against gravity, and grip fails because grip needs a stable extended wrist to work at all
- Weakness with no numbness anywhere. This is a specific and easily missed pattern. See AIN and PIN palsy
- Neck. Weakness plus a stripe of numbness down the arm. See cervical radiculopathy
Muscle wasting is the finding that changes urgency. Compare both hands in the same light, palms up then palms down. A hollow where the other side is full means the nerve has been struggling for months, not weeks.
Tendon weakness
Not weakness so much as absence. One specific movement is gone completely, and no amount of trying produces it.
- Fingertip won’t bend at the last joint after a grab or a tackle — see jersey finger, which has a surgical deadline measured in days to a couple of weeks
- Thumb won’t lift off a flat table, weeks to months after a wrist fracture — see EPL rupture
- A cut to the palm or finger followed by a finger that won’t bend — see flexor tendon injuries
- Fingertip droops and won’t straighten — see mallet finger
If it hurts, treat the pain and the strength follows. If it doesn’t hurt, find out why the message or the rope has failed — and find out soon.
Three tests you can do at the kitchen table
- Paper pinch. Hold a sheet of paper between thumb and the side of your index finger while someone pulls it away. If your thumb tip collapses into a bend to hold on, that is an ulnar nerve sign
- Flat table thumb lift. Palm flat on the table, lift only the thumb straight up. If it won’t come off the surface after a wrist fracture, that tendon has likely ruptured
- Isolated fingertip bend. Hold the middle joint of one finger straight with the other hand and bend just the tip. No movement means the deep flexor tendon is not attached
None of these replaces an assessment. All of them tell you whether to wait a fortnight or ring on Monday.
Get it assessed now if
- Weakness came on suddenly with no injury and no pain
- You can see wasting — a hollow, a flattened thumb pad, gaps between the bones
- One movement is entirely absent rather than reduced
- You are dropping things without noticing
- Weakness is getting worse week on week
A grip that hurts is usually a problem you can wait on. A grip that is simply gone is a deadline you cannot see.
For what measurement and assessment actually involve, see what a hand therapist actually does.
Every article on this site is written using the Closing Window Method: name the window your condition runs on, find where you are in it, and act while it’s still open.