Interval run training

I had a go at some interval run training yesterday. I started with a 10 min warm up run at 155 bpm followed by running about 300m at 180 to 185 bpm then another 300m slow jog recovery. I repeated this for about 20 min and then a 5 min warm down run. My calf muscles were tight after so I did plenty of stretching and filled the bath with cold water and dangled my legs in (Im not brave enough to get right in it yet). I read in Mens Health magazine that tap water temperature was as good as an ice bath. I do not know if it helped but Im going to stick with it to test it if my muscles are sore.