Quote Originally Posted by 5 alpha victim View Post
I see what you are saying with the adrenaline rush. The other day I tried thirty second sprints at 12.5 MPH with two minute breaks in between each sprint.

I would usually do one minute sprints (more like fast runs) at 10mph for sixty seconds with sixty second breaks in between each sprint. Although this was all-around more difficult and a better work work, I still feel that jolt/adrenaline feeling more after doing the faster pace for the shorter distance which seems to be the point here.

I am still doing them on a treadmill though and will probable change to a track eventually.

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Doing on outdoors, on a track, or even a little bit of an incline if you're a badass, is definitely more taxing and you get more from it than on a treadmill. The acceleration part that is taken out in treadmill sprints as you 'join in' at a fixed pace, and that is the explosive element that you get a lot of benefit from, physically and hormonally.

I do them on a treadmill at the moment purely down to a niggling lower back issue but soon will be back to outdoors... I do get the benefits from treadmill but its not near as good as in the great wide open.