I have just bought a miband pulse (like a Fitbit but budget) and have set it to vibrate when my heart rate exceeds a certain level. At the start of my run my heart rate shot up to about 162 then after I had got into it my heart rate settled at about 142 ish. Is this the usual pattern as your brain realises what your doing and gets your heart beating more efficiently or did I just slack off? Didnt feel like I did! Did consciously go slower than my w4r1 effort and only covered a little less distance so must have been walking faster in between. I think the key is not to have extremes of pace.