10x400m Intervals — The Best Session for Getting Faster And Here's Proof

10x400m intervals at 4:15/km pace. No carbon plate, stupid heat, and no wind. This is the session I credit for both my 5km and 10km personal bests — and it's probably the most effective speed session you can do as a runner. The format is simple: 10 reps of 400m at a challenging but controlled pace, with 100m of recovery in between. That's it. No complicated plan, no fancy structure. Just 10 reps, enough rest to go hard again, and the discipline to show up and execute every week. Do that consistently and you will get faster. Guaranteed. The best part? The whole thing takes 40 minutes or less. If you're a runner short on time but serious about getting faster, this is your session. Workout breakdown: 10 min easy warm up 10 x 400m @ target pace (mine: 4:15/km) 100m easy recovery between reps 10 min easy cool down Total: ~40 min Chapters: 0:00 Today's session — 10x400m vs threshold 0:34 Warm up — already hot with no wind 0:58 Shoe choice — no carbon plate today 1:48 Rep 1 — finding the pace 1:57 Why 10x400m works 2:32 Rep 2 — settling in 3:00 The system — how to get faster week by week 3:45 Rep 3 4:28 Rep 4 5:02 Why this works even with limited time 5:29 Rep 5 — halfway approaching 5:59 Rep 6 — officially halfway 6:46 Rep 7 — starting to hurt 7:37 Rep 8 — going to the dark place 8:17 Rep 9 — two to go 9:22 Rep 10 — give it everything 10:50 Done — what 10x400 actually means 11:37 Cool down — ASICS Evo SL verdict 12:37 Execution score and final pace breakdown 13:04 The plan going forward — dropping pace over time 13:34 Wrap up Connect with me: Strava:   / strava   Instagram:   / riderunrepeat.ct   Gear: 2025 Specialized Stumpjumper 15 Alloy Comp: https://freewheel.co.za/products/stum... Silverback Slade: Tyres: https://schwalbetyres.co.za/product/s... Rims: https://alexrims.com/products/evo-2-3... Hub: https://www.on-lynecomponents.com/pro... Grips: https://www.ergonbike.com/en/article-... Chainring: https://www.on-lynecomponents.com/col... Radar: https://www.garmin.com/en-ZA/p/698001/ Garmin Mount: https://www.garmin.com/en-ZA/p/1610737/ GPS Watch: https://www.garmin.com/en-ZA/p/866230/ HRM: https://www.polar.com/za/sensors/h10-... Running Shoes:    • Running Shoe Rotation - Spring 2025