How does treadmill function work, I do 1,6km which is 1 mile and always do about 2000 strides, yet garmin says it is only 1.3km..so I adjust stride length accordingly, yet garmin still says I do 1.3 km...I have adjusted stride length from .5 metre to 1.5 metres...but garmin still says 1.3km...what does garmin measure...obviously it should be strides x stride length...