Different Times on Different Treadmills, what is the main difference?

[TheBlackRabbit]

On equal levels of rest I can...

Run a 5:17 mile on this older model life fitness treadmill (80's-90's version)
5:40 on a newer model at the gym

On my 6 month old Gold's Gym treadmill I have at home from walmart, I can only do 2 miles at 6:40 a mile, guessing my best mile would be around 6:20. It feels like I have to use much more energy per stride, like I am running in quicksand. My legs are more sore after running on it, and then switching to another treadmill the next day feels like I am floating almost.

Anyone have any idea what makes the difference? Speed Display vs Actual Speed discrepancy? The suspension in the treadmill?

 

[Miramonti]

Stick to the older treadmill. At that pace you'll get a better workout.

If the incline's are equal, they aren't calibrated the same. Your body resistance could be affecting the flow of the tread at varying degrees between each of them as well, making the run slightly more inconsistent and harder.

 

[neocpp]

For the faster times (5:17 and 5:40), do they actually feel different or are you just going by what the treadmill is telling you? I know you said that on your GG treadmill, it's like you're running in quicksand and that switching to another is a lot easier (presumably because of a harder surface). That is probably the primary effect, although I think most of them aren't calibrated that well either. I wouldn't worry about it too much unless you're looking for certain times, and in that case I would actually advise you go on a track so you know it's the right distance. With a time like 5:17 on a treadmill I think you can break 5:00 on a track; at the very least, you'll know which one gives you the most accurate measure of your ability.