Interval Runs vs Tempo Runs vs Fartlek Runs: Simple Explanation & Examples - Lee Grantham

Aug 13, 2025

Intro: This is a quick summary of Interval Runs vs Tempo Runs vs Fartlek Runs: Simple Explanation & Examples from Lee Grantham. It’s a great watch — we’re breaking it down so you can try the workout today. Be sure to check out the full video for all the details.

Key Points:

Interval runs are short, high‑intensity repeats (e.g., 6 × 1 km or 20 × 1 min) aimed at speed and speed‑endurance (V O₂ max).
Tempo (threshold) runs are longer steady efforts (20–40 min) at or just below lactate threshold, boosting aerobic capacity and race‑pace sustainability.
Fartlek runs mix continuous running with varied‑intensity bursts (e.g., ladder 200‑400‑600‑800‑1000 m and back) to develop both aerobic and anaerobic fitness while keeping training fun.
All three workouts manipulate effort, not just pace—adjust for heat, terrain, or how you feel.

Workout Example:

Interval Session: 6 × 1 km at your 5K target pace with 1‑minute easy jogs between reps.
Tempo Session: 20 min at a comfortably hard pace (~10 % faster than your marathon pace) – aim to stay just below lactate threshold.
Fartlek Session: 200‑400‑600‑800‑1000 m ladder, then reverse, running each segment ~20‑30 % slower than your race pace with 200 m easy jogs between.

Closing Note: Try one of these runs this week, tweak the paces to match your own training zones in the Pacing app, and watch your speed and endurance improve. For full explanations and more variations, watch Lee Grantham’s video – then customize the workout to fit your goals!