Do not apply heat to swelled or bruised muscles
If your muscle is swelled or bruised, you should never apply heat to it. Remember that applying heat to muscles in such conditions will only make the things worse and you would suffer even more damage. You must never apply heat to muscle that is suffering from both or any of these injuries. The reason for not applying heat is that heating the muscle will cause the blood flow in the affected area which will only make things worse. For such injuries, you must prepare a pack of ice and apply it to the muscle until your swelling is in control. The duration is dependent on the extent of injury, but you must apply the pack of ice for at least 10-15 minutes.
Heat the medical pad
After your swelling is under control and has started reducing, you must start heating the medical pad. If you do not have the medical pad, there is no need to panic, you can ask your friend or neighbour to buy you one from the nearest drug store. Now you must warm the pad to the temperature you can bear on the affected area. Do not heat the pad too much. Nevertheless, if you do not have the pad, you can always warm the water and put it into a water bottle. For this, consider warming the water in microwave or a pan.
Apply it to the affected area
After you have warmed the water or pad, you must get a towel. Do not try to apply it directly to the affected muscle. You must wrap your affected area with a towel and place the water bottle or pad over it. You must apply heat at least three times a day but not more than 20 minutes.