How can an athlete determine if pain is from training or from an injury?

The difference between pain from training, and a pain from injury, we tend to see pain from the injury last a little bit longer. Most overuse type injuries, a kid will come to us, and say, "Hey, I've had pain for five to seven days." While, we see a lot of the pain, or the pain from training comes from direct onset of muscle soreness, which lasts normally about 48 to 72 hours. If their pain lasts longer than that, then they tend to come see us, and say, "Hey, it's been four or five days, and this isn't getting any better." Then that's when we go ahead and start treating them.