Joint Pain
Joint pain, particularly in the joints of the knee, ankle, elbow and wrist, should never be ignored. Because these joints are not covered by muscle, pain here is rarely of muscular origin. Joint pain that lasts more than 48 hours requires a physician’s diagnosis.

Tenderness at a Specific Point
If you can elicit pain at a specific point in a bone, muscle or joint, by pressing your finger into it, you may have a significant injury. If the same spot on the other side of the body does not produce the same pain, you should probably see a doctor.

Nearly all sports injuries cause swelling. Swelling is usually quite obvious and can be seen, but occasionally you may just feel as though something is swollen even though it look normal. Swelling usual goes hand-in-hand with pain, redness and heat. Swelling within a joint often causes pain, stiffness, and may produce a clicking sound as the tendons snap over one another after having been pushed into a new position from the swelling.

Reduced Range of Motion
If swelling isn’t obvious, you can usually find it by checking for a reduced range of motion in a joint. If there is significant swelling within a joint, you will lose range of motion — the limb will only go so far in each direction. Again, compare one side of the body with the other to identify major differences; if there are any, you likely have an injury that needs attention.

Comparative Weakness
Comparing one side to the other for weakness is often hard to do, but can be helpful when assessing an injury. One way to tell is to lift the same weight with the right and left side and look at the result. Or try to place body weight on one leg and then the other. A difference in your ability to support your weight is another tip-off to an injury that requires attention.

Numbness and Tingling
Never ignore numbness or tingling. Such sensations are often related to nerve compression, and these warning signs may indicate serious injury that should always be seen by a doctor.