For whatever, reason, I find that when I run on the treadmill for the same effort as on “hard land”, I am moving around ~10% slower. It really does not matter which treadmill, I am just slower on the treadmill than at the track. I have not run much except on the treadmill all winter. I only started really shuffling/jogging/running after > 1 year break this winter. and almost all the running is on treadmill. I did a few outdoor runs, but with the recovery from a disk-nerve issue, the softer surface of the treadmill is easier on me.
In any case, the last two weekends, I headed to a local indoor track and was surprised by my times (not that they are that fast, but way faster than on the treadmill). For example, 120 seconds per 400m is 5 min per kilometer. That’s basically 7.5 mph. On the track this speed feels like jogging even with my limited strength/range of motion in my left leg.
On the treadmill 7.5 mph or 12 kph feels like a pretty decent clip. I would not be able to keep this up for a long time (like 20 minutes) on the treadmill. On the track, 96 second lap is 4 min per K pace or 9.3 mph/15 kph. This feels like a steady clip, nothing killer on the track but on the treadmill 9.3 mph/15 kph feeling quite hard. At this point, I have not gone that fast on the treadmill YET, but at at the track I was actually get a decent amount faster without trying “that hard” (my cardio is good for me from a lot of super hard swimming so I did not want to overdo it).
But this is not really new for me. 10 mph used to feel like a full out sprint on the treadmill. This is only 90 second per 400m which was not that hard in the past! 10 mph/16kph would literally feel like 80 second per 400m for me. I could barely stay on the treadmill for 80 seconds at that pace, but running on hard ground no problem basically going 80 second 400m pace which is 18 kph. Unless I am going pretty easy, the treadmill speeds vs “running on hard ground” really diverge.
I can only attribute this to a less “hard” push off on the treadmill since the belt is going at constant velocity under your body, but on hard ground you are doing a slight deceleration on landing and pre loading/compressing, allowing for a harder push off (unlike running like the road runner with the legs spinning like the road runner).
I remember Allan Faulds talking about doing some short treadmill intervals at 11-12 mph a few years ago and feeling totally off. 12 mph is 3 min per K pace.or 72 seconds per 400m. He said something along the lines of being able to run around that fast for 400m on the track, but unable to do that for the equivalent of a lap on the treadmill.
I don’t run on the treadmill but I feel the same way about the indoor bike trainer vs. outdoor cycling. Im always amazed at how much easier it feels to ride outside at the same effort than indoors.