If a 6mm only put you at 180, you must have been around 120 for that 9.5mm. Seems like a really strange workout, especially if you have a coach telling you to do that.
Well, it was only on my schedule as a 20 min run. I decided to see what a rough mile time would be so I just kinda did it in the middle. I usually just put it at 7-8 mph and run till time is up. I don’t remember my 9.5mm heart rate but at about 8.5mm i am @160.
Even still it follows the basic interval or warmup-effort-cooldown format so its not weird.
No running goals. I do it for cross training and an alternate aerobic workout.