Whatever you call it – training, working out, exercise, PT – some level of intense physical activity at regular intervals is part and parcel of being in the military.

This could include anything from rucking several pounds of combat gear, running, or playing sports to lifting weights.

One of the keys to a service member’s ability to stay physically fit and avoid undue long-term damage to their body is knowing the difference between “normal” aches and pains and what may be signs of something more serious.

“There are several indicators that your body will give you when determining whether you are experiencing normal discomfort or ‘good’ pain, in a way, versus pain that needs to be addressed,” said Air Force Capt. Kameryn Corcoran, a physical therapist at David Grant USAF Medical Center at Travis Air Force Base in Fairfield, California.

Some of the key indicators, she said, are:

• Pain during activity
• Duration, or pain that continues after ending an activity
• Pain that limits the duration or intensity of your activities

“These are the things you want to look for when thinking about whether to push through or stop,” said Corcoran.

Running injuries, specifically, are usually recurrent or nagging aches or pains that start and progress without obvious injury, said Navy Lt. Cmdr. Aaron Stoll, a physical therapist at Naval Hospital Jacksonville, Florida.

Stoll said these injuries normally fall into two categories: training errors or overuse, and lack of preparation.

“The first category can result in aches, pains, and declining performance and can be signs that you’re overloading and need a couple days off to recover,” he said. “The latter can cause plantar fasciitis, hamstring tightness, patellofemoral pain syndrome, ‘runner’s knee’ or IT (iliotibial) band syndrome. Others may develop hip or back pain with running due to stiffness of the leg muscles or trunk.”

While these types of conditions are not usually a sign of serious injury, they can and should be dealt with to prevent the symptoms from worsening and to optimize continued performance, said Stoll.

It’s essential to understand the difference between “good” and “bad” pain. Good pain or soreness is a normal response to pushing your body past its current level of tissue load tolerance. Stiffness and aches after working out can be completely normal, said Corcoran.

“If you push past that soreness and overload the capacity your body has at that point, that’s when you start to get closer to a risk of injury,” she said. “Often, I’ll tell patients to adhere to a 10% progression rule. If you’re increasing your activity more than 10% per week, you are at risk for overloading your tissues or structures at a rate faster than what they are able to adapt or recover at properly.

If any pain persists longer than three to five days, it’s likely a good idea to consult a medical professional as this may be a sign of potential injury.

In terms of pain levels, “Try not to overthink it,” Corcoran said.

A good analogy – and a simplified version of the Defense and Veterans Pain Rating Scale – is to think of a stoplight.

“Green light is if you’re experiencing pain between a zero and a three. If you’re between a four to a six, you’re more in the yellow light range and you should start to slow down and think about what may be causing your discomfort – technique, posture, etc. Seven to 10 means you should stop and potentially seek medical attention, especially if it’s acute pain,” said Corcoran.

Signs that an injury or pain may be serious include sharp pain that prevents your normal range of motion or prevents a part of your body from moving altogether, pain associated with a significant amount of swelling, deformity or bruising, or pain that lasts past the five-day threshold, especially if a person hasn’t put any stress on that part of the body since the pain began. You should also seek help if the pain is constant, gets worse or keeps you awake at night.

Regardless of whether or not the pain is something serious, giving your body time to recover is always recommended.

“The key to building strength is the time during which your body is recovering,” Corcoran said. “That’s when your muscles rebuild. That’s when your structures get stronger and adapt."

If you’re not allowing for that recovery time, she said, we’re breaking down our body without getting the positive benefits.

In the event that an injury is serious, the quicker the intervention, the higher the likelihood of a quick recovery.

A sprained ankle for example, can turn into chronic pain or may place undue stress on other parts of your body surrounding the ankle due to overcompensation if left unaddressed.

“We can get you back to full function a lot faster than if you ignore the signs of overtraining and push through the warning signs,” said Corcoran.

When it comes to running, Corcoran recommended changing your running shoes every three to six months or every 250 to 500 miles, depending on how frequently you run.

“Running is a high impact sport, so you want to make sure your body is ready for that impact and you’re loading it in a way in which it’s able to adapt properly without exposing yourself to an increased risk of injury,” she said.