16-Week IRONMAN 70.3 Training Plan for Bolton 2026 (Intermediate)

Plan Overview

This 16-week training plan is designed for intermediate triathletes targeting IRONMAN 70.3 Bolton on 7 June 2026 — or any 70.3 race in early to mid summer. Starting in mid-February, the plan builds systematically from your current fitness base to full race readiness across all three disciplines. You should be able to swim 1km continuously, cycle for 90 minutes, and run for 45 minutes before beginning this plan.

Prerequisites

• Can swim 1km continuously in the pool
• Can cycle for 90 minutes at moderate effort
• Can run for 45 minutes without stopping
• Has completed at least one sprint or Olympic distance triathlon
• Access to a pool, road bike or turbo trainer, and outdoor running routes
• Approximately 8–10 hours per week available for training

Plan Structure

The plan is divided into four phases, each building on the last with a recovery week every fourth week to allow adaptation and prevent overtraining:

• Weeks 1–4: Base Phase — Building aerobic capacity across all three disciplines. Emphasis on technique, consistency, and establishing your training routine. Volume: 7–8 hours per week.
• Weeks 5–8: Build Phase 1 — Increasing session duration and introducing threshold work. First brick sessions appear. The long ride extends to 3 hours. Volume: 8–10 hours per week.
• Weeks 9–12: Build Phase 2 — Race-specific intensity. Long ride extends to 3.5–4 hours, long run to 1h 45min. Open water swims in wetsuit. Volume: 9–11 hours per week.
• Weeks 13–14: Peak Phase — Highest volume and intensity of the plan. A 70.3 simulation weekend in week 13. Volume: 10–12 hours.
• Weeks 15–16: Taper — Volume reduces by 40–50% while intensity is maintained. Race rehearsal in week 15. Full rest in the final 2 days before race day.

Sample Week (Build Phase 1 — Week 6)

A typical week from the first build phase gives you a sense of the training load and balance between disciplines:

• Monday: Rest or 20-minute easy recovery swim with drills
• Tuesday: 45-minute threshold run at 80–85% max heart rate, structured intervals
• Wednesday: 60-minute turbo trainer sweet spot session (88–94% FTP)
• Thursday: 45-minute CSS swim set in the pool — main set 10 x 100m at threshold pace
• Friday: Rest or light stretching/yoga
• Saturday: 3-hour endurance ride outdoors, moderate effort, with 30 mins nutrition practice
• Sunday: 75-minute brick run directly off the bike — first 15 mins at race pace, then easy

Bolton-Specific Preparation

IRONMAN 70.3 Bolton is a notoriously hilly race. The bike course includes sustained climbs that can break athletes who have not prepared specifically for them. Build climbing strength into your training from the early weeks — use hill repeats and seated climb sessions on the turbo. The run course is also undulating, so practice running off a hilly bike rather than expecting a flat recovery run.

Key Tips for Success

• Consistency beats heroics: Missing one session is fine; missing three in a row derails a plan. Prioritise sleep and recovery.
• Nutrition is the fourth discipline: Practice your race-day nutrition on every long ride and run from week 5 onwards. Aim for 60–80g of carbohydrate per hour on the bike.
• Open water preparation: Get into open water at least 4–6 times before race day. Your first OW swim in a wetsuit should not be on race morning.
• Taper confidently: Reduced volume in weeks 15–16 is part of the plan, not a sign of under-training. Trust the process.