How to Polarize Training for Triathlon

The most important piece of two intensity or more for the advanced athlete is intensity. Most athletes try to do most of their training in the region just above the aerobic threshold up to their anaerobic threshold which is kind of middle ground. I'm amazed how fast it's being taken out by athletes with something called the training stress score (TSS) that quantifies the workout that you do not only in terms of duration but also in terms of intensity and putting it into one number so I can say this workout was a TSS of 100.