There is no such thing as a good or bad workout - only good and bad execution. The magic is in the execution, and this is a concept that still confuses a lot of athletes, so let me break it down.
The Problem With Searching for the Perfect Session
When athletes want to improve in a discipline, they search for something like "workouts to run a faster 5km." They find videos prescribing sessions based on distances or time with rest intervals, often with no mention of target intensity or the overall physiological goal.
Did some of those workouts help create world champions? In a way, yes. But it was not the workout on paper that made the champion. It was how they executed it.
Three Sessions That Look Similar But Do Completely Different Things
Here are three run sessions built from the same simple building block - one-kilometre repeats. They look almost identical on paper, but they target entirely different energy systems.
Session 1: VO2 Max — 4 x 1km at 96% max heart rate with 4 minutes recovery. A 1:1 work-to-rest ratio, pushing above threshold while staying below maximum aerobic capacity. This is pure top-end aerobic development.
Session 2: Upper Threshold — 6 x 1km at 92% max heart rate with 2 minutes recovery. A 2:1 work-to-rest ratio with slightly more volume at a lower intensity. Excellent for overall ATP yield and serves as a foundation for almost any race distance.
Session 3: Sub-Threshold — 10 x 1km at 88% max heart rate with 1 minute recovery. High volume at a manageable intensity. These sessions still drive threshold adaptations but can be done at very high volumes and are easy to recover from. This is the go-to for middle and long-distance intensity training.
Why Simple Sessions Are More Effective
One-kilometre repeats can be written an unlimited number of ways to prepare for any race distance. The magic is not in the structure - it is in the intensity, the rest, and the intent behind each repetition.
This is why simple sessions are so powerful. When the structure stays constant, you can isolate the variables that actually matter: how hard you go, how long you rest, and how much volume you accumulate. Using heart rate to guide your intensity makes this even more effective.
Variety vs Optimality
In coaching, athletes tend to fall into two categories. Some want the most optimal training possible and are happy to repeat simple, effective sessions week after week. Others prefer variety and are willing to sacrifice a small amount of effectiveness in exchange for sessions that feel more engaging.
Both approaches work. If you are mentally focused, simple repeats with adjusted intensity and rest will get you the best results. If you struggle with monotony, over-unders, ladder sets, and mixed-format sessions can keep you engaged - even if they do not offer additional physiological benefit beyond making the session easier to complete mentally.
The workout does not make the athlete. The execution does. Stop searching for the perfect session and start executing the simple ones properly.