Similar: I ran for about 10 years until I was 25 (only 3 miles a day), then I just had to quit due to knee soreness. At the time I was about 170lbs, which is no feather, so this might have something to do with it.
I can't believe these people who refuse to give up running -- I see them hobbling along at 5mph with bandages all over them, and I feel like yelling out: "just take up cycling...jeeez".

From my experience, running was always harder than cycling over a similar duration -- any way you wanna mix either of them up, running is MURDER by comparison. It also requires more preparation than cycling (eating and drinking too soon prior, etc). It's also much less "smooth" and comfortable; I'd say I would only have felt good during ~2 out 5 five runs.

Having said all that, posting this message has made me realise how much I miss it , but the last time I tried it my chrondomalacia flared up after only 1km. The "runner's high", sometimes achieved when everything goes perfectly, and you're flying along at 10mph, is quite unique.


Koffee, as I'm sure you're aware, running is much better for bone density.............and 70mins a day??!!!??? That is A LOT!!!
Are you sure you were going 4mph? That's almost a brisk walk.

Like the other poster said, the soreness is most likely you not being used to the movement, but for those that don't know: running is much harder on the legs becuase of the eccentric muscle contractions (lengthening under load). Cycling is virtually ALL concentric (muscles shorten under load). This is why marathon runners can only do so many marathons a year, but the Tour de France riders can ride 6 hours a day, day after day.

PS One of my favourite ever lectures at uni was on sarcomeres (etc) and muscle contractions. Funny how you always remember the interesting stuff at the exam.