Muscle strain, muscle pull, or even a muscle tear refers to damage to a muscle or its attaching tendons.  You can put undue pressure on muscles during the course of normal daily activities, with sudden heavy lifting, during sports, or while performing work tasks.   Almost anyone can put undue tension on muscles during the course of normal daily activities, with sudden, quick heavy lifting, during sports, or while performing work tasks.  Strains are a result of muscular fiber tears due to over stretching; they are very painful.  Although strains are not restricted to athletes and can happen while doing everyday tasks, people who play sports are more at risk of developing a strain.

The first-line treatment for a muscular strain in the acute phase include five steps commonly known as RICE:

• Protection: Apply soft padding to minimize impact with objects;
• Rest: Rest is necessary to accelerate healing and reduce the potential for re-injury;
• Ice: Apply ice to reduce swelling by reducing blood flow to the injury site. Never ice for more than 20 minutes at a time;
• Compression: Wrap the strained area to reduce swelling with a compression bandage;
• Elevation: Keep the strained area as close to the level of the heart as is conveniently possible to keep blood from pooling in the injured area.

Learn more at Wikipedia