DOMS (delayed-onset muscle soreness) is a normal part of exercise. It's caused by micro-traumas to individual muscle fibres, and results in pain for 24-72 hours after exercise. It requires no first-aid at all, but some athletes say that using an ice-bath will reduce the pain.
Injury-related pain, however, is a trickier affair. Obviously, it's not a normal part of exercise, but the cause, duration of pain, and type of first-aid varies from injury-to-injury. In most cases, though, first aid MUST be applied within the first 24 hours.
The more eagle-eyed amongst you will have noticed that the first-aid window for injuries is shorter than the average life-cycle for DOMS. That means, you have to diagnose DOMS (or not-DOMS) without using the pain's duration as a guide.
This is more difficult than it sounds. Depending on the severity of your DOMS, and which muscles are effected, if can feel very much like an injury. For example, when I get DOMS in my deltoid, it feels almost exactly like bursitis. A friend of mine swears that his quadriceps DOMS feels just like a corkie.
Distinguishing DOMS and injury pain is difficult, but it can be done. This is my guide:
This is not an exhaustive list, and you should always err on the side of caution. If you're not sure, treat it as an injury. Use RICER and call your sports health professional.
If you want more information on DOMS and injury, email me directly via the contact page. If you want specific information about your own injury or if you're after treatment for an injury, contact one of my clinics directly to make an appointment. Details of those clinics can be found here.
Dr Mitch Clark