Tempo Runs are “Comfortable Hard”, what is “comfortable”? This is where we use the information we learned at https://www.mcmillanrunning.com from the pace calculator. In short, you will be pushing the pace faster than you normally run but it is also at a pace that is sustainable. While you are running you should be thinking "I can do this and maintain the pace but it takes a lot of effort to do. Temp runs differ from lactate threshold (LT) runs in that the am LT run is bordering on the maximum effort for the distances and could not be sustained. Together these are incredible workouts, but also must be done properly. Many of us will start doing LSD + tempo run, meaning the first 6-7 miles were of easy pace, with the last 3-4 at tempo pace. The biggest focus is on the actual pace.
How do I incorporate this? It’s at the pace where you are feeling your systems (muscular, cardio, respiratory, etc) stress fairly hard, though not “all out”. You should be thinking “Damn, I’m running really strong right now.” However it’s easy for runners to got a bit too much over that comfort zone, believing that the extra effort is better for training. So if you’re instead thinking “Damn, this really sucks!!! L ” (I”ll call it the TRS zone ;) then you may be pushing too hard, or your body may not be trained enough to be at this level. If this is you, consider doing more of the LT Interval workouts before going to full-time Tempo pace or even getting another few weeks of general aerobic (easy) time on your feet. Being in the TRS zone for days and weeks on end cause burnout and potential dropout in addition to possible injury. It takes practice to determine what your Lactate threshold (LT) pace really is. Good luck!!