My 6.8 Xterra runs like a club treadmill and then some. My knees have taken a toal over the past 40 plus years and I found the club units too stiff. The 6.8 is soft but firm. I find less impact on my knees from pounding the deck. I usually jog 3 miles per day at 3% elevation. I use my heart rate control monitor / via chest strap to gauge my target heart rate while I’m working out. I find the Ipod docking station helpful while I watch my Xfinity per-programs shows. The speaker system sounds fine and I do not have to adjust the volume to compensate for the treadmill noise. Really a good deal. I highly recommend this treadmill to anyone!