Why identifying the root cause of injuries is difficult

Many of you know of my past injury issues which have included Runner’s knee, AT and PF. The past 12+ months, however, I’ve pretty much run injury free with no missed running days due to injury or pain. However, I did closely track what I’ll refer to as “tension” in my right knee which is since completely gone but it could have easily turned into a bad case of Runner’s knee.

That’s the background but the issue is trying to determine the cause of the “tension,” and that’s where it gets really tricky. I looked back at my log and running diary and here are the key points in time that point to the beginning of the issue but isolating what was the primary cause and/or if it’s a bit of everything is the real trick in analyzing the cause of potential running injuries.

1. Week of 10/18. I started double sessions running AM & PM, 3 times per week. At the end of the week, I notice tension in my right knee.
2. Week of 10/25. I reduce the double sessions to 2 times per week but did 2 runs in my new Inov-8 F-Lite 195’s. I also ran too hard on my Sunday long run which I essentially turned into a 10 mile tempo run at a 6:45 pace. By the end of the week, the tension is coming and going but not impacting my running.
3. Week of 11/1. I carve back on the miles a bit (50mpw) and mix Evo and Nike Zoom Streak XC (“XC”) running and no tension in the knees and that included AM/PM running.
4. Week of 11/8. One of my heavier mileage weeks (60+ miles for the week) with a mix of Evo, XC and Katana running. By the end of the week, tension in my right knee returns.
5. Week of 11/15. I’m still running fast times and the tension in the knee is still there, coming and going (some days something, other days nothing), but I start running a bit slower on my easy days.
6. Week of 11/22. I do a whole week of 100% Evo running and by mid-week all tension is gone and hasn’t returned since and I’ve been running pretty hard but I added more mileage to each run and stopped the double sessions.
I only list this to point out how darn delicate all of this is.

Was the problem due to increased mileage by adding AM/PM running?

Was it the increased intensity on some of my longer runs turning them into tempo runs?

Could it be the shoes (XC’s, Katana’s, etc.) since I did a full week of Evo running with no issues (but 2 weeks I mixed Evo and XC without any problems)?

Was it the introduction of the new F-Lite 195’s?

Did it go away by running easier on the easy days?

Is it a combination of all the above?

If I had to bet money, I’d say it was the increased mileage with double days but who knows for certain. It’s very tricky and it’s why I don’t automatically say it’s the “shoes,” as there are so many other factors. It can be difficult isolating the specific cause and it may be as simple as “any change,” requires slow adaptation.