12/09/2025
Zone 2 training is good — but Zone 5 is better.
The key to faster 5K and 10K times?
Easy days must be easy, but hard days have to be truly hard.
Most runners log plenty of Zone 2 miles — great for building aerobic capacity, mitochondria, capillaries, and reducing injury risk.
But if you don’t spend enough time in Zone 5, you’ll plateau.
Zone 5 training forces your body to:
⚡ Handle race-specific intensity
⚡ Use fuel more efficiently at high effort
⚡ Buffer and reuse lactate
⚡ Boost VO₂ max — the ultimate driver of performance
Ways to add Zone 5 work:
🏔️ 2-min steady hills 8-12 reps — heart rate spikes faster than flat speedwork. Jog down easy.
⚡ 1–2–3 min Fartlek at ~3K effort, half-time recovery. Do 3 sets with 2 min between.
🏃 8-12 × 800m faster than 5K pace with just 30s recovery so HR stays high.
Zone 2 builds the engine. Zone 5 unlocks the speed.
👉 If you’re not doing this every 2-3 weeks, you’re missing the key to real performance gains.
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