Marathon Pacing Simulation: 8km Run Session

Session Overview

This 60-minute session teaches you to run at marathon pace — the exact effort you’ll sustain on the run leg of an Ironman or 70.3. At 8km, the distance is long enough to build pacing discipline but short enough to recover well from. Ideal for intermediate athletes building toward long-course racing.

What You’ll Need

• GPS watch with pace alert
• Flat or gently undulating road or path
• Water (carry it or plan a route near fountains)

Warm-Up (10 minutes)

Run 1.5km at very easy pace (RPE 3–4), finishing with 4 x 20-second accelerations to bring your legs to target pace. During each acceleration, build smoothly to marathon pace and hold for 20 seconds, then jog back to easy pace.

Main Set

Run 8km at target marathon pace — the pace you aim to hold for your race run leg. Use your GPS to keep pace consistent throughout with a gentle progression:

• 0–2km: Marathon pace +10–15 seconds per km (ease in gradually)
• 2km–6km: True marathon pace — your target zone (RPE 6–7)
• 6km–8km: Marathon pace −5 seconds per km — a mild negative split finish

Cool-Down (5 minutes)

Reduce pace to easy jog for 1km, then walk for 2 minutes. Stretch hips, calves and hamstrings — hold each stretch 30–40 seconds.

Coaching Notes

• If you don’t know your marathon pace, use this formula: current 5K time × 2.2 = approximate marathon pace in min/km
• Common mistake: running too fast in the first 4km and fading — the final 2km should feel controlled, not desperate
• Make it harder: extend to 10–12km at marathon pace, or do it after a 60-minute bike session (brick)
• Make it easier: reduce to 6km at marathon pace with the same structure
• This session pairs well with your long ride day — run it 4–6 hours after cycling