thanks guys, I went for a run on the beach today (on vacation for the night and forgot running shoes so I went barefoot. ouch.) and it was ALOT harder, of course I know running on the beach is harder, esp. barefoot, than any other ground but I was alot more sore and winded, kinda a reality check because I havent felt like that on a treadmill, even at 8-9 miles. So I will be doing more running outside, again thanks everyone for your feedback!!