Also-Ran I also had some trouble last year with my intervals as they generally left me very sore the next few days and I felt like I was on the edge of injury. I think because of longer stride length, quicker turnover and applying more power. I tried to manage it with streching and foam roller. I ran them on flat tarmac. Since November I've been doing hill reps and have had no re-occurnace of the pain. The purpose is a bit different as a hill rep is more to gain leg strength and the (flat) interval is more about leg turnover and form. I generally run flat intervals at 6:00 to 6:20 pace and hill reps at 6:40 to 7:00 pace. I'm not suggesting that hill reps replace flat intervals, but it maybe give you a break if you mix it up.
The other overlooked way to run fast is a downhill interval - useful for giving the leg turnover speed and the stride length minus the power. You've got to select hill with moderate gradient so there is no requirement for breaking from the quads other wise it is counterproductive.
Akatrigs - I'm a big believer in strength work, I just don't do much. I use the swiss ball, dumbell and kettlebell in dynamic, multiplanar excercises that emulate the movements in running. Just doing isolated moves like biceps curl is pointless IMHO. If you sit all day at a desk like me then you may find your core is relatively weak and you need to strengthen it and activate it. Core strength is of course linked heavily to good running form.
Thanks for the welcome back everyone - Achilles seems fine today but I'm still going to be cautious and leave the running until next week. I had an Achilles problem in 2011 that took around 9 weeks and many trips to the physio to fix and don't want a repeat.
Edited: 03/01/2013 at 08:41