Stretching Before and After
Stretching out your hands and fingers before and after you play can help prevent problems with straightening your fingers after playing. Simply opening and closing your fingers to bend and flex the muscles in your hand can help. Complete this simple bending and flexing both before and after you play. If you play for a longer period of time, stop between every couple of songs to work your fingers to prevent them from cramping as you play.
Individual Dexterity
Some chords and techniques you use while playing the guitar may require you to straighten some fingers while you use other fingers to play. Therefore, it is important to train your muscles to keep some fingers straight while bending others on the same hand. For this exercise, hold your hand flat with all of your fingers extended. One at a time, bend each finger while keeping the others straight. It will be difficult at first, but will get easier over time. Once you can bend each finger individually, work specific finger combinations as well.
Finger Joint Exercise
To help increase the strength and flexibility of your fingers to help ensure you can straighten them after playing the guitar for long periods of time, exercise the joints individually. Hold your fingers out straight. Slowly bend your fingers in to make a fist, bending first the joint nearest the tip, then the middle joint and finally the joint closest to your hand. Reverse the process to open your hand. Complete this process on each finger on both hands to encourage your fingers to straighten again, no matter how often or how long you play the guitar.
Treatments
If you develop problems, such as tendinitis or trigger finger from playing the guitar, you may require medical treatment. However, there are other things you can do at home as well. Avoiding playing for four to six weeks can help alleviate your symptoms. However, if you make a living from playing, that may not be an option. Soaking your hands in warm water and massaging them can offer you relief if you must still play. You may want to wear a splint while you sleep to help train your fingers to straighten again.