In August 2021, I raced my first half Ironman on home turf in Boulder, CO. Among my friends on
the CU Triathlon Team, doing a 70.3 after graduation was something of a rite of passage. So, in
the months leading up to the race, I felt both proud that it was finally my turn and a bit uncertain.
I’d spent four years training for short-course races – either redlining for an hour in sprint
distance races or riding the edge of my comfort zone in Olympic distance races. But this felt like
a new beast entirely.And I made it even beastlier by setting the goal to qualify for 70.3 Worlds at that race – even if it
meant seeing stars at the finish line.
‍
All goals and silliness aside, I learned a lot during the build for that race. One of the most
important tools I added to my training toolbox was understanding how to hit the right zones,
power numbers, and paces in workouts. I was lucky to have an incredible coach – D3’s very
own Brad Seng – guiding me physically, mentally, and emotionally (because let’s be honest, we
all shed a few tears chasing big goals!). Through plenty of trial and error, he taught me how to
train and race smarter.
‍
About three weeks out from race day, Brad dropped a daunting run into my TrainingPeaks
called “Half Marathon Tempo – Mile On/Mile Off.” It totaled 14 miles: 2 miles to warm up, 10
miles alternating pacing in an over/under format, and a 2 mile cool down.
‍
The main set went like this:
● Odd miles at open half marathon pace (the pace you’d run for a standalone half
marathon, which is usually faster than your off-the-bike pace).
● Even miles 30-45 seconds per mile slower – not quite a recovery pace, but enough to
shift gears without letting up.

The challenge? There’s no built-in recovery. But that’s the beauty of it! The workout teaches
your body to keep running under fatigue, which is exactly what happens when you start a half
marathon after biking 56 miles.
I’ve since repeated this workout in other half Ironman builds, and I now use it with my own
athletes (but all kudos to Brad!). Here's the structure:

The Workout
● 2-mile warm-up – Include some strides to elevate your heart rate and prep for intensity.
● 10 miles alternating – Odd miles at open half marathon pace; even miles 30-45
seconds slower. I based my paces on a 5K time trial from earlier that summer.
2-mile cool down – Run this very easy. No shame in shuffling here, or yogging, as I like to call it!

Tips for Success?
● Nutrition.
● Water.
More nutrition. Bonus points if you use your race-day plan to practice fueling and train
your gut!
● Pacing discipline. Don’t burn all of our matches out of the gate. If you crush the first few
reps, you’ll likely end up in the pain cave and miss the targets in the second half – which
defeats the purpose entirely.

This workout is best done with a GPS watch and heart rate monitor. I used both to stay within
myself and avoid overrunning. If you're a coach, prescribe pacing and HR zones based on
previous testing – it makes a big difference!

The Takeaway
The real key to nailing this workout – and any big training day – is discipline and belief in
yourself. It was the hardest run I did in my Boulder 70.3 build, but it showed me what I was
capable of. There’s nothing more empowering than realizing the strength within yourself to do
hard things and chase big goals!

‍