After finishing my first sprint triathlon in a time that left me proud but breathless, I spent six weeks building a proper 12-week plan from scratch. This is the exact week-by-week structure I used to complete my second sprint — 27 minutes faster than the first.
The Structure: Three Phases
A 12-week sprint plan divides naturally into three phases: base building (weeks 1–4), intensity (weeks 5–9), and taper plus race (weeks 10–12). Each phase has a distinct objective. Mixing them — doing high-intensity work during a base phase, or adding volume during taper — is the most common amateur planning mistake.
Phase 1 — Base (Weeks 1–4)
- Swim: 2×/week, 1000–1500m per session. Technique-focused. No speed work.
- Bike: 2×/week, 45–60 min Zone 2. One Zwift session, one outdoor ride.
- Run: 2×/week, 25–40 min easy. Cadence above 170 spm.
- Total weekly volume: approximately 4–5 hours.
Phase 2 — Intensity (Weeks 5–9)
- Swim: Add one speed set per session — 6×50m at race effort, 30s rest.
- Bike: One session per week with 3×8-min threshold intervals. One long ride (90+ min).
- Run: Add one interval session — 6×400m at 5K effort. Keep one easy run.
- Brick workout: Every two weeks — 45-min bike followed immediately by 15-min run.
- Total weekly volume: 6–7 hours at peak.
"The brick session is non-negotiable. Your legs will feel alien for the first 3 minutes of the run. That's exactly what race day will feel like — practise it."
Phase 3 — Taper (Weeks 10–12)
Week 10: reduce volume by 30%, keep one quality session in each discipline. Week 11: reduce volume by 50%, sessions are short and sharp — no new stress. Race week: easy movement only, three short sessions (20 min each), no fatigue.
What I Would Change
Looking back, I underestimated transition practice. I did exactly one T1 and T2 run-through before race day. Next time, I include a dedicated transition rehearsal in week 9 — full gear, full sequence, timed. The three minutes I lost fumbling with my helmet buckle and race number belt were completely preventable.
Week before: confirm race logistics, pack transition bag, test race nutrition. Two days before: carb-load, sleep early. Morning of: breakfast 2.5h before start, arrive 90 min early for setup, warm up with a 5-min easy swim before the gun. The pre-race routine is as trainable as any workout.