TRITRAINBack to the start ↗THE SCIENCE BEHIND YOUR PLAN.
THE TRITRAIN METHOD.
Most training apps ask you to trust their algorithm. We would rather show our work.
The TriTrain Method™ distills decades of peer-reviewed endurance research into four principles — and four numbers that prove your plan is following them. The research informs our planning; it does not endorse TriTrain.
1. Train mostly easy
About 80% of training at low intensity, 20% hard. It is the pattern behind the world's best endurance athletes — and behind faster age-group Ironman finishes.
Informed by: Seiler, IJSPP 2010 · Selles-Perez et al., JSSM 2019
2. Build the base your distance demands
Bank easy hours before adding intensity. Research on Ironman triathletes found that more time in Zone 1 is associated with faster finishes.
Informed by: Muñoz et al., IJSPP 2014
3. Taper with intent
Cut volume 41–60% in the final weeks; keep intensity and session frequency. A proper taper is worth 2–3% on race day.
Informed by: Mujika & Padilla 2003 · Bosquet et al. 2007
4. Structure in blocks
Base → build → sharpen → race. Each phase has one job, so adaptations stack instead of colliding.
Informed by: Issurin, Sports Medicine 2016
Four numbers that prove it
In the final three weeks before your race, a fifth number appears: Taper Readiness, tracking your volume reduction toward the 41–60% taper zone. It shows up exactly when it matters.
How your plan is built
Your goal sets the direction; your current training sets the starting point.
Choosing a full-distance triathlon creates different demands than choosing a Sprint — longer endurance work, different sessions, a different progression. But choosing a longer race doesn't mean your body is immediately ready for more training. TriTrain also considers your experience, current weekly training, available time, preferred rest day, and time until the event.
Someone training five hours a week won't suddenly receive fourteen just because they selected an Ironman. The app starts from your current training and builds within your availability. And if your availability sits below the race's planning range, it says so — a mismatch highlighted is better than a plan you can't follow.
Zones answer "how hard" — not "how fit"
A zone is a guide to the effort a workout is intended to develop. TriTrain uses different references per sport:
| Sport | Threshold reference |
|---|---|
| Run | Threshold pace and sport-specific threshold heart rate |
| Bike | FTP and cycling threshold heart rate |
| Swim | A swim-specific pace benchmark — how to set yours |
The bands are Friel-derived threshold zones — the zone structure from Joe Friel's published guidance, applied per sport. (Selected Strava zones can override them.) To be clear: this is not the complete Friel training method. The plans combine TriTrain's own progression, workout selection, and recovery adjustments.
The distinction that matters: a race goal tells us where you want to go; a benchmark helps determine an appropriate intensity today. An ambitious finish goal shouldn't automatically make your training paces faster.
Full guides: Setting your training zones · Your swim pace benchmark
You can start without knowing your numbers
TriTrain begins with effort descriptions and whatever you already know. Imported activities add evidence over time. The automatic running guide looks for repeatable pace information from recent runs — easy-effort evidence first — and when that's unavailable, enough comparable heart-rate data can support a provisional guide.
Every number carries a label, so you always know where it came from:
An observed pace at a relatively low heart rate is useful guidance — it isn't proof of your physiological Z2 or threshold. The labels keep that honest.
The plan responds to your training
TriTrain reviews recent training separately by sport: completed volume, known session outcomes, reported effort, estimated load, and recovery feedback. Then it adjusts — by explicit software rules, not vibes:
| What the app observes | How it may respond |
|---|---|
| Consistent training with adequate recovery | Gradual increase within your available time |
| Two or more sessions reported as very hard | Reduce upcoming volume, keep sessions easy |
| Completed training below the schedule | Bring the plan closer to what you're actually doing |
| Poor recent recovery feedback | Hold or reduce training instead of building |
| Too little reliable history | Keep collecting evidence and explain the limitation |
One protection matters: unlogged does not automatically mean skipped. The app needs enough known outcomes before making some adjustments.
Adaptation you can understand
A changed workout is more useful when you can see the reason:
"Upcoming running volume was reduced because two recent sessions were reported as very hard."
Every adjustment connects three things: the evidence, the decision, and the affected training. Your completed workouts are preserved, and when the future plan changes, the history stays as the record of what you actually did.
Different questions, different answers
Preparation, performance, and recovery are kept distinct:
- Race preparation — what does your accumulated training say about readiness for this distance?
- Performance estimate — what finish range does your data support?
- Daily recovery — how are you feeling and responding right now?
- Target time — what outcome do you want to pursue?
A high preparation score doesn't guarantee a target time. A faster training run doesn't prove improved fitness if it cost much more effort. More data can raise confidence — or reveal limitations and lower an estimate. Both are the system working.
The method, in one paragraph
The TriTrain Method™ builds a plan around your race, experience and available time, then adjusts upcoming training using your completed sessions and recovery feedback. It explains what changed, shows where estimates come from, and makes missing information visible.
That's the distinction: established training concepts, combined with accessible data, practical adjustments, and clear explanations.
The research
- Selles-Perez et al. (2019) — Polarized and pyramidal training intensity distribution: relationship with a half-Ironman distance triathlon competition. Journal of Sports Science and Medicine, 18, 708–715.: Read the paper
- Muñoz et al. (2014) — Training-intensity distribution during an Ironman season: relationship with competition performance. International Journal of Sports Physiology and Performance, 9, 332–339.: Read the paper
- Seiler, S. (2010) — What is best practice for training intensity and duration distribution in endurance athletes? International Journal of Sports Physiology and Performance, 5, 276–291.: Read the paper
- Stöggl, T. & Sperlich, B. (2015) — The training intensity distribution among well-trained and elite endurance athletes. Frontiers in Physiology.: Read the paper
- Mujika, I. & Padilla, S. (2003) — Scientific bases for precompetition tapering strategies. Medicine & Science in Sports & Exercise, 35(7).
- Bosquet, L. et al. (2007) — Effects of tapering on performance: a meta-analysis. Medicine & Science in Sports & Exercise, 39(8).
- Issurin, V. B. (2016) — Block periodization versus traditional training theory: a review. Sports Medicine, 46, 65–75.
We link to the publisher or an open-access version wherever available, and cite from brief summaries rather than reproducing the work.
Go deeper: the method guides
Two practical guides that put the method to work — each one a page of its own.
- Setting your training zones — the 30-minute test, FTP, Friel-derived bands per sport, and how TriTrain keeps every number honestly labeled.
- Your swim pace benchmark — the 400m test, technique-first guidance for beginners, and what TriTrain does with your number.
Train on the science
The TriTrain Method is built into every plan, from Sprint to full distance. Start with two weeks free.