How we train for triathlon.

Context

At Splits we treat triathlon as one integrated system, not three parallel plans. Our priority is managing total weekly load across all three disciplines rather than maximizing each one in isolation.

Cycling delivers 50 to 60 percent of total load in mid- and long-distance events, so that's where most of our planning energy goes. Swim and run get distributed according to your level and your goal. We apply the per-sport methodologies we already published — VDOT, FTP, CSS — but we orchestrate them so the hard sessions don't pile up on consecutive days. And we always keep at least one full rest day on the calendar.

Methods

Three families inform our triathlon plans. We picked them for the evidence behind them and for how well they fit athletes with limited weekly hours.

• Distributed 80/20

  Fitzgerald and Warden propose keeping 80% of combined load in the easy aerobic zone across all three sports. We use it as the year-long reference frame for beginners and intermediates.

• Polarized vs pyramidal

  Half-Ironman studies show both distributions work. We like polarized in pre-season and pyramidal closer to race day, with more specific zone 2 work.

• Traditional or reverse periodization

  Joe Friel orders the year Base → Build → Peak → Taper. Reverse starts with intensity and layers volume in later. We apply the first for beginners; the second works when winter limits long outdoor sessions.

How we derive the numbers

For triathlon we don't project event times because they depend on how you combine your paces across each segment. We anchor on the official distance instead: every format (sprint, Olympic, 70.3, Ironman) has a fixed profile of swim, bike, and run. The table below shows those profiles, which are the base on which we layer our per-sport methodologies.

Sources

We back every decision with accessible literature. The four sources below are our primary references for triathlon; we revisit them whenever we need to sanity-check load mix, intensity distribution, or seasonal phase order.

• Joe Friel — Periodization of Intensity (Triathlete's Training Bible)joefrieltraining.com
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• Matt Fitzgerald & David Warden — Understand your 80/20 Triathlon Training Plan8020endurance.com
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• Scientific Triathlon Coaching Team — Polarized vs Pyramidal Training Periodisations in Triathlonscientifictriathlon.com
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• TrainingPeaks Coaching Team — Reverse Periodization for Triathlon TrainingTrainingPeaks
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When it doesn't apply

These methods cover an amateur triathlete with limited time and adequate technique across all three disciplines. There are moments when it pays off to step outside the frame we propose; here's when, and why.

• They don't replace a coach who knows your history in each sport and can adjust the load mix week by week.
• If your swimming technique can't yet cover 750 m non-stop, we suggest focusing on swim work alone for a few weeks before tackling the full plan.
• For Ironman on under 8 weekly hours the model falls short: the minimum aerobic volume is hard to hit and the injury risk climbs.
• Any pain that persists across disciplines (knee on bike and run, shoulder in swim) deserves medical evaluation before more training.