Nobody holds top speed all the way to the line. Every sprinter on earth, Bolt included, is slowing down over the last 20 meters of a 100. The race is not won by whoever speeds up at the end, because nobody does. It is won by whoever slows down the least. So the real question is not why you decelerate. It is why you decelerate more than the people beating you. Three things cause that, and all three respond to training.
Most high schoolers reach max velocity around 30 to 40 meters and then have to survive the rest. Trained sprinters push their peak back to 55 or 60 meters, so there is simply less track left to slow down over. The fix is acceleration development, a longer, more patient drive phase, not more flat-out speed work. A later peak is a shorter fade.
Holding velocity past 60 meters is a different fitness quality from being fast. If you only ever run short sprints with full recovery, you never train the system that keeps speed alive once fatigue shows up. Flying 30s, runs at 95 percent, and short speed-endurance sets from 80 to 150 meters build it. This is the single most skipped piece in high school training.
The classic last-20 mistake: you feel yourself slowing, so you try harder, you clench your jaw, your fists, your shoulders, and that tension shortens your stride and slows you down more. Fast finishers relax. The cue is simple, keep the face loose, run tall, and let the speed come to you. It feels passive. It is faster.
Late-race deceleration shows up as a stride that shortens and a posture that breaks down, and both are invisible at full speed. Film a whole sprint from the side, the AI marks the phase where your mechanics change, measures whether your stride is collapsing or your posture is, and tells you which of the three causes is yours.
Follow up in chat and ask questions. The AI remembers your analysis and speaks the language of sprints coaching.
Peak velocity in the 100m arrives around 55 to 60 meters for trained sprinters and earlier for developing ones. Push the peak back and the fade gets shorter.
Common questions athletes and coaches ask about this topic.
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