Terms All Runners Should Know | Fartlek, VO2 Max, Yasso 800s Explained - The Running Channel

Aug 13, 2025

Intro: This is a quick summary of Terms All Runners Should Know | Fartlek, VO2 Max, Yasso 800s Explained from The Running Channel. It’s a great watch — we’re breaking it down so you can try the concepts today. Be sure to check out the full video for all the details.

Key Points:

Intervals = set distance or time (e.g., 2‑minute fast run) followed by recovery (e.g., 1‑minute jog). Often called “reps.”
Splits = time for each segment of a run; can be used to track negative splits (second half faster) or even splits (same pace).
Fartlek (Swedish “speed play”) = a steady run with random bursts of speed—by time, distance, or landmarks.
VO2 Max = max oxygen uptake; typical values 30‑60 ml/kg/min for most, 80‑90 for elite. Labs measure it, watches give rough estimates.
Pronations (over‑, under‑, normal) affect shoe choice and injury risk.
Yasso 800s: 10 × 800‑m repeats at a target total time (e.g., 2 min 40 sec) was once used as a marathon predictor, but it’s not reliable for race pacing.
Progressive runs = gradually increase pace every 10 min or each mile/kilometer.
Strides = 20‑second fast bursts used for warm‑up or mid‑run.
Foot strike varies (heel, mid‑foot, fore‑foot); mid‑foot generally considered efficient.

Workout Example:

Warm‑up: 10‑minute easy jog

Main Set – Fartlek / Interval Mix (5 × 2‑min fast + 1‑min jog):
  • Run 2 minutes at a hard‑effort pace (≈ 85‑90% of max effort). 
  • Recover 1 minute easy jog or walk.
  • Repeat 5 times.

Cool‑down: 5‑minute easy jog

Tip: Adjust the fast‑pace to match your recent race pace (e.g., 5‑K pace) and keep recovery easy.

Closing Note: Give these terms and the quick fartlek interval a try on your next run—customise the paces in the Pacing app to fit your fitness. Have fun experimenting and watch your confidence grow! 🚀