The challenge here is that there is no linear causality between VO2max and LT.
As a goal, the correlation to strive for is FTP watts coming in above 85% of VO2max watts, even shooting for as high as 90%. I've read about athletes being as high as 95% but that was from the mid-2000s which tells me the data was relying on EPO-juiced athletes, whether the lab coats knew it or not. So, I would say shooting for an 85-90% correlation between FTP and 5min maximal output tests is the goal.
The correlation is about metabolic efficiency - how well can the body process lactate before OBLA occurs (Onset of Blood Lactic Acid). OBLA is when lactate production "tips" and is produced faster than the body can process it - typically around 4mml (millimoles) of lactate. Within that 85-90% correlation mentioned above, you're not necessarily "better" if you're higher. If you're naturally stronger at VO2max, then your correlation would be lower, or visa versa if you're naturally stronger at FTP. As an example, Frank Shorter had a pedestrian VO2max but a super high LT. Which is why he was "just ok" in the 5k/10k but world champ at the marathon.
If your correlation rises above 90% and closer to 95%, then it’s time to look at your VO2max as a limiter and start focusing on opening the body up. VO2max tends to be a limiter when your body is inefficient at transporting O2 to the working muscles during intense exercise. The only way to become more efficient is to train your VO2max system. For those who track power, this would equate to L5, or 106-120% of FTP. For those who only train by HR, this would equate to 90-95% of Max HR.
Conversely, if your correlation is below 85%, then you probably need to spend some time focusing on your LT. Power-wise, this is L4, or 90-105% of FTP; even SST is a great zone to focus on at 88-93% of FTP. In HR terms, this would be 84-92% of Max HR.
For those using power in their cycling training, this is the whole reason to perform the 1min, 5min and FTP tests. When you collect the data points and better understand their correlation, you can start to better focus your training because you have identified your limiters and can specifically attack them. By doing this, you will get more out of your training, reduce the negative impact of your weak spots and, ultimately, allow yourself to experience greater successes in competition.
Happy Training,
Coach Nate