I’ve posted before about how every run should have a purpose. Before you step out the door for your workout, you should already know what the training stimulus you are trying to achieve from the run you are doing. Too many times, runners will brag about completing a run faster than prescribed. If running fast reps is good for training, then running faster must be better right?! Nope.
Let’s say you have two runners who are prescribed the same VO2 max workout, 3 x 4 minute repeats at VO2 Max pace, with the purpose of getting 12 minutes of work at VO2 Max pace. Let’s also say that that VO2 Max pace for these runners is an even 7:00 minute/mile pace. This will keep the math easy. The table below shows two runners who completed the prescribed workout.
As we can see, runner A completed the workout as prescribed, while runner B “banked” time on the first rep finishing a tad slower on the final split. So who had the better workout?
If we look at average pacing and total time of the reps, it might seem like runner B had a better workout, correct? They had a faster average pace, and overall faster time when we add the intervals together. However, what was the purpose of the workout again? Time spent at VO2 Max. So let’s look again.
Runner A ran consistently at the prescribed pace and completed the workout of 12 minutes at VO2 Max pace. Runner B ran the first rep too fast. You do not gain additional VO2 Max benefits by going above pace. VO2 Max is the maximum amount of oxygen consumption. So if you are trying to train that system and you go over, you don’t achieve additional benefits to the energy system you, or your coach, is trying to stress. Instead you begin working a different energy system and add additional, and unnecessary stress and fatigue to your body. The second rep for runner B was on pace and achieved the desired training impact. Then, because the runner was tired, they fell off the last rep, never reaching VO2 max. Thus, not getting the additional time at the desired training level. Runner B got maybe 8-10 minutes of training at VO2 max pace.
So which was better? Which runner was able to get the most out of the workout, while fatiguing the body less? If the two runners continued this pattern which runner would accumulate fatigue faster and risk over training?