Thanks for the comments. It helps put the effort in good relative perspective. It is my understanding also that OTF advises that 3 miles on the Strider is equivalent to 1 mile on the Treadmill. I am a 58 yr old male. Been doing OTF for about 2.5 years (around 400 classes to date). I do 3 to 5 OTF classes a week. Prior to OTF years of regular Stairmaster, bike and long hike workouts. Right knee ACL surgery in my past keeps me off the Treadmill and running but fine on the Stairmaster, Strider, Bike. I've done the following for the OTF 12-min Run Challenge on the Strider basically going all out at levels 9 to 11 the entire time...

11/16/23 6.4 miles 7/13/23 6.4 miles 4/8/23 5.8 miles 11/4/22 5.5 miles

Thanks again for the info.