Hi Robert, I'm on for my first half marathon in a couple of weeks and I tend to get sore knees and sometimes calves after my long run (over 13 miles), the important thing is that I then rest completely for a day and a half, after which I resume my training probably with a 6 mile jog at easy pace.

I also do the frozen peas thing after my long run, although I must say it seems to work better with frozen sweetcorn ;-)

Have been upping my mileage recently but not overly so but last few runs have felt a twinge at the top of my left calf behind my knee, happens at stat of run but goes away fairly quickly but I am noticing that I fel twinges when not running so have been massaging and there is definately some soreness there, booked in for a sports massage so hopefully that will help, but have half-marathon in 4 weeks so don't want to reduce running to much, but may have to reduce back on my miles.  Anyone had anything similar