Grade: 3
Leaning over to pick something up, something tweaked in my back and since then movement has been painful - like a stiff neck, but in the back. It responded well to heat & ibuprofin - enough to run lightly the next day. Not sure about racing on 3/5, as jumping over stuff hurts...
Just a 'stiff back' like a 'stiff neck'. Time helped it go away - I even ran a race and was okay.