400m is the hardest sprint to pace. Go too hard early, you blow up. Go too easy, you lose. The optimal split is consistent: roughly 1.5-2.0 seconds slower for the second 200m than the first. Here's the full 400m strategy, from start to finish, plus how AI grades your form when fatigue sets in.
The fastest 400m runners hit roughly 50/52 (first 200/second 200) splits, regardless of total time. That gap, around 2 seconds, is the strategic target. Faster front halves blow up; slower don't gain enough time on the back end.
Most 400m athletes have good form fresh and ugly form fatigued. AI grades both, you see what your form actually looks like at the 350m mark, when the race is decided.
The form errors that cost you a 400m are predictable, head dropping back, shoulders tightening, arms crossing. AI flags them in the last 80m specifically, so you can train through them.
The 400m is decided when form starts to break. Most athletes don't film fatigued reps. Upload one and AI tells you exactly which mechanic broke first, plus how to train it back.
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Common questions athletes and coaches ask about this topic.
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