Fingers locking up!

I have had two times were my fingers will start to curl, and I have to manually stretch them out onto the wall.  Has anyone else had this happen? 

Dehydrated? I've had it happen when I get dehydrated while climbing. 

Try doing opposition exercises that require forearm extension instead of flexion.

Trigger finger? Kinda sucks when you can’t place a cam because your finger won’t work. Try drinking more water and electrolytes, that usually prevents it for me.

MD here, my differential diagnosis:
1) cramps: if this only happens when you're pumped on the wall, and you can slowly release the spasm, it's cramps.  I get this in my wrist muscles when climbing splitter cracks doing the same motion over and over again over- fatiguing one muscle group

2) If this happens all the time, especially first thing in the morning, and there is a distinct "pop" you have to overcome to get your finger straightened, then it's trigger finger, go see a hand surgeon. Don't freak out, the first things he/she will try are nonsurgical (steroid injections).

Thanks Sam! Cramps sounds more like the issue I'm having.  It's nice to hear someone else has had to deal with the issue, it sucks! 

Liquid Calcium/magnesium supplements help muscle function/recovery. 

I planted threes for a number of years and we had something we called "the claw". Basically the hand gripping the shovel all day - the next morning you'd wake up with pretty only a closed/open position in your grip, without really being able to go in-between. Felt like a switch - could only go from one position to the other, no in-between. Seemed it was due to constant effort from (possibly over) gripping all day. Warming up (moving around, stretching) would get ride of it. Unsure if what you're talking about is similar.

People usually just kept planting and eventually went away as the body got used to it. Dunno if anyone got more serious problems from that or no, but at least no to my knowledge, though it did feel kind of scary.

I started drinking Snake Juice on climbing days and my cramping issues have resolved. It's kind of like Gatorade w/o the sugar.
Per Liter H20:
- Potassium Chloride Powder (i.e., No Salt) = 1/2 tsp
- Himalayan Pink Salt = 1/4 tsp
- Baking Soda = 1/2 tsp
The taste might be too strong at first, so just mix up the dry ingredients separately and add as much as you can stand, slowly increasing the concentration over time. 

Potassium magnesium aspartate and water do the trick.

Just remember the old saying - finger locks or pinewood box.

Yes, thank you Sam for the post! I've definitely woken up to find my fingers locked into the rock and roll sign. t's terrifying - like complete paralysis/tetany of the finger unless you pop it back into place? It usually takes mine ~10 minutes to relax after waking up. I just avoid resetting it and let it do its thing.

Another (even better) option is to get some isotonic, stir it in yer water bottle (I would suggest to half the recommended dose, e.g. if they advise to stir one spoon per 12oz of water, stir one spoon per 24oz to reduce that way-too-intense taste) and hydrate properly. Lazy/rich man solution is to hydrate with (preferably sugar free) Powerade or Gatorade. Almost the same effect (even better due to solid maltodextrin dose).

Personally I just intake 2 pills of potassium magnesium aspartate pills with my breakfast on climbing days. It is cheap as shit and prevents any cramps.