A muscle strain or muscle pull is an injury caused when a muscle is stretched too far.
Some of the muscle fibers break, just like over stretched rubber bands.
The result is painful, but if not too bad and can often be treated without a visit to the doctor.
The RICE method is usually recommended to deal with strains.
RICE stands for Rest, Ice, Compression, and Elevation.
If you've strained a muscle, stop using it until it gets better.
This may take a couple days, weeks, or longer depending on the damage.
It's going to hurt and you won't feel like using it anyway.
Of course, total rest may be impossible so rest as much as you can.
For example, I stained my leg's hamstring muscle most recently, but still had to limp through the airport to get home.
Ice works wonders to reduce swelling.
I usually use ice cubes in a ziplock bag wrapped in a towel, and apply several times a day in 20-30 minutes sessions.
Ice packs work well too.
Compression can help a lot too.
An elastic bandage for example can be used to restrict swelling.
Elevation.
Get it up in the air! Gravity will keep fluids from pooling in your injured muscle and further swelling.
You don't need it sky high, just above the rest of your body.
A simple muscle strain, while painful and inconvenient, is not serious.
You can treat it with RICE.
Of course if in doubt as to its severity, don't hesitate to visit your doctor or hospital.