IRONMAN 70.3 Boulder

Get to the swim start early enough to settle into your lane/seed. Do a quick warm-up in the water if available, then practice calm breathing and a steady first stroke cadence so you don’t sprint the first 50–100 m. Position with people of similar pace, and plan to sight efficiently early—Boulder’s swim is about staying smooth until you’re clear of traffic.

You’ll cover 1.965 km in freshwater with temperature that varies, so start slightly conservative and let your body find rhythm. The key is to keep your effort controlled in the first portion while you work through the initial crowd, then build toward a steady, repeatable stroke rate once traffic thins. Drafting and frequent sighting become your best friends—use line-of-sight to stay on course and avoid unnecessary zig-zags. Fueling during the swim isn’t the goal; focus on exiting the water composed and ready to absorb the first hard leg of the day with clean breathing.

Plan a swim→bike T1 flow that’s simple and practiced: rack your bike, put on socks/shoes as efficiently as you can, then prioritize hydration and a controlled first acceleration. As you mount, settle your breathing and start building to your target power gradually—don’t surge right after the dismount area. Treat the first rolling miles as setup for the day, not the place to “find speed.”

You’ll ride 90.5 km with 561 m of rolling elevation, so expect repeated small surges—stay disciplined and let your power match the terrain rather than chasing the hills. With wind around 4.6 m/s from the W, stretches where you’re riding across or into the wind can feel like they change the bike’s “feel” quickly; keep your effort steady in those moments rather than spiking. In hot conditions, fluid and sodium management matter: your fueling target is 90 g carbs per hour with 1000 mg sodium per hour and about 800 ml fluid per hour. Use that as your baseline intake plan and keep sipping regularly rather than trying to catch up. Because it’s rolling, consider taking fuel on the easier sections while you’re still smooth, then maintain hydration through the harder parts—your goal is to arrive at T2 ready to run.

Plan T2 so your legs feel ready to transition: after the bike, stand up and reset your posture briefly during the changeover, then start running with shorter, controlled strides. Expect some heaviness in the first minutes off the rolling bike—your job is to find an efficient cadence without sprinting the first stretch. Since the run is flat/fast with 21.7 km and only 69 m gain, settle into rhythm early and then build sustainably.

You’ll run 21.7 km on a mostly flat/fast profile with just 69 m of elevation—so the limiting factor becomes heat and hydration rather than climbs. In hot conditions, start the run by keeping effort controlled for the first segment; the fastest-looking pace early often leads to late fade. Continue your race fueling and hydration strategy consistently (don’t wait until you feel thirsty), and prioritize steady intake so you don’t under-fuel in the middle miles. The wind (west, ~4.6 m/s) may create alternating headwind/tailwind sensations—use it to manage effort, not to “race the air,” and keep your form tall and relaxed. Because the course is flat, small pacing errors compound—aim to lock into a sustainable cadence and let the last portion be where you try to raise intensity, not where you recover.