Mark Allen on Mastering the Long Game: The Rule of Thirds

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In the heat of an Ironman, a common mistake athletes make is dividing the race in half. We tell ourselves, “I’ll control the first half and hammer the second.” But as Mark explains in this video, the “second half” of an Ironman leg is a daunting, often insurmountable distance that leads many to “die” well before the finish line.

The solution? The Rule of Thirds.

By breaking both the bike and the run into three distinct phases, you shift from a mindset of survival to a mindset of hunting. Here is how to execute the perfect build:

1. The First Third: Conservative Discipline

This is the hardest part of the race—not physically, but mentally. While everyone around you is riding or running like they are in an Olympic distance race, your job is to stay steady.

• The Goal: Hold back from the pace you know you can sustain.

• The Reality: People will pass you. Let them go. You are preserving the “artificial self-confidence” and glycogen that others are burning too early.

2. The Second Third: Sustainable Race Pace

By the middle of the leg, the initial adrenaline has worn off. This is where you settle into your solid, honest race pace.

• The Goal: Find your rhythm and hold it.

• The Reality: This is where you stop losing time to the leaders. While they begin to feel the weight of their early efforts, you are just getting started.

3. The Final Third: See What You’ve Got

In an Ironman, the race truly begins at mile 70-75 of the bike.

• The Goal: Increase the effort. If you’ve paced correctly, you will hit this section at an equal or faster pace than the middle third.

• The Reality: This is where the magic happens. While the rest of the field is slowing down and struggling, you are speeding up. There is no greater psychological boost than “hammering” the final third and catching athletes who overextended themselves hours ago.

“The first third, everybody looks like Superman. By the final third, they are slowing down and you are speeding up. That’s how you win races.” — Mark

Takeaway: Don’t let the distance intimidate you. Stop looking at the halfway point and start building in thirds. Your strongest self should be the one that crosses the finish line.