You train hard. You follow a well-balanced program, eat well, sleep enough and put good emphasis on recovery, but your shins still hurt.
Usually people with overuse injuries are not this disciplined, but it can happen to the best of us.
The body breaks down and does not recover on a small scale until finally it fails.
Shins are the most common, but it can happen to muscle, bone, tendons and ligament.
Shin splints are a general term for any pain on the front of the shin, but it can affect the muscle or the bone. It can happen for many reasons, but usually it is due to too much, too soon.
The volume exceeds the recovery; in this case rest usually resolves this problem.
In the case of our disciplined person, the issue can be an overlooked movement dysfunction, especially if the pain is one-sided. In this case the person should follow up with a health-care professional to find where the dysfunction resides.
The breakdown does not always have to be localized to one body part. The breakdown can be systemic and lead to something called overtraining syndrome. The literature still has a hard time clearly pinpointing how to detect this but most symptoms include:
Decreased training drive
Decreased tolerance of training
When this starts to happen, time off or active recovery is advised.
It has been monitored by some trainers by taking heart rate or grip strength first thing in the morning before getting out of bed. This is charted and if heart rate increases or grip strength decreases it might be best to take a day off.
This has had success anecdotally, but is not well represented in journals. When in doubt, rest and if it does not resolve shortly seek medical attention.