Negative Split Long Run: 70-Minute Progressive Build

Session Overview

This 70-minute progressive long run trains you to run faster in the second half of your effort — the negative split approach that separates good run splits from great ones in triathlon. Starting conservatively in zone 2, you’ll build through zone 3 and finish with a strong zone 4 push in the final 10 minutes.

What You’ll Need

Warm-Up (10 minutes)

Begin with 10 minutes of easy jogging at RPE 3–4, keeping your heart rate below zone 2 threshold. Use this time to settle your breathing and get your joints moving. No need for additional drills — the easy pace is the warm-up.

Main Set

The negative split progression builds across three phases. Each phase should feel noticeably harder than the previous one — if phase 3 feels easy, you started too fast. Every phase is 20 minutes.

  • Phase 1 (minutes 10–30): Zone 2 — RPE 5, comfortable conversational pace
  • Phase 2 (minutes 30–50): Zone 3 — RPE 6–7, can speak in short sentences, pace picks up noticeably
  • Phase 3 (minutes 50–70): Zone 4 — RPE 7–8, approaching threshold, controlled but hard

Cool-Down (5 minutes)

Walk briskly for 3 minutes after finishing, then jog gently for 2 minutes at RPE 2. Stretch hip flexors, hamstrings, and calves for at least 5 minutes once back home to reduce next-day soreness after the hard final phase.

Coaching Notes

  • Check your pace data afterwards: your final 20 minutes should be 30–60 seconds per km faster than your first 20 minutes. If not, you started too fast.
  • Don’t panic in phase 3 — the discomfort is temporary and productive. Focus on your form: tall posture, quick cadence, relaxed shoulders.
  • Beginners: reduce to a 50-minute session (10-10-10 minute phases) and build to 70 minutes over 4 weeks.
  • This run is best done 2–4 weeks out from your target race. In race week, replace phase 3 with an easy zone 2 effort.

Training at your own risk. The information provided is for general guidance only and is not a substitute for professional medical advice. Please consult a doctor before starting any new exercise programme, especially if you have any pre-existing health conditions.