http://exercise.about.com/cs/cardioworkouts/l/blinterval.htm
simply alternate speed walking, running or hills for 1-2 minutes with 2 minutes of slow walking to recover.
http://exercise.about.com/cs/cardioworkouts/l/blinterval.htm
simply alternate speed walking, running or hills for 1-2 minutes with 2 minutes of slow walking to recover.