I took a week off of running to clear up some shin pain and my first run back was on the treadmill at 2 hours(Wednesday). I did the run up a 1-2% grade. I had already worked my way up to a 2 hour run in my training, and actually the last run I did before I took the 1 week break was a 2 hour run. That run was up a 3-4% grade, and I had done a few other runs before that up 1-2% grades. But running at an incline is still something relatively new to my training.
Anyways I was feeling some minor discomfort during the 2 hour run on Wednesday, and a little the day after. Then, yesterday, I did an 85 minute run (with 60 min threshold), I did this run at a 0% incline (except the warm up) and was feeling a little pain, but nothing major. This morning (saturday) when I got up it was alot worse.
The pain I am talking about is mainly on the underside of my Navicular and Medial Cuneiform. There is some minor swelling and I cannot press directly on a pinpointed area that would be indicative of a stress fx, so hopefully I can rule that out and just be dealing with soft tissue problem. If I put on a shoe with major arch support the pain is alot worse than being barefoot. I am not sure if this is due to the soft tissue in that area being stretch out and causing more pain, or if the arch is able to put more pressure directly on the possibly stress fx bone and cause pain. Early today it hurt to walk, and I was walking with a limp. It has gotten better as the day has went by. I feel little to no pain when riding. When I have iced, it is more sore after icing.
Very similar recent experience. I attributed it to running on an incline on the treadmill. I took about 10 days off and have since limited my long runs to outdoors and have stayed away from anything longer than 45" on the treadmill. Fortunately my pain has gone away and hasn’t returned. It really doesn’t make much sense to me as I never had problems running on the treadmill before. The only thing different this time was adding grades and doing hill repeats. Good luck with your problem. I hope it is only short lived like mine was.
Likey insertional posterior tibial tendonitis. The PT tendon has many distal insertions, but it’s major one is right on the underside of the medial navicular. Running hills does put a little stress on it, as does the dreadmill which for many runners is not quite as natural a gait. You did mention some slight localized swelling to the area too, right? Another way to get this going is direct irritation to the area (not as common). Also, many people have a small accessory bone right here (os tibiale externum) that also can predispose you to this type of injury.
However, navicular stress fractures are not that uncommon in runners. A stress fx of the medial cuneiform is highly unusual. Navicular stress fractures never show on plain film X-rays, even after several weeks, so an MRI is usually done if clinical suspicion is high. If you aren’t improving in a reasonable amount of time with std. ice, rest, etc., it should probably be ruled out as they are notoriously slow to heal (if ever) and often require surgery (much like a scaphoid fx in the wrist).