The Split Decision: Weighing Front-End Speed vs. Back-End Strength in the 100 Freestyle
When you’re targeting a world record in the men’s 100 freestyle, every decision you make around pacing carries consequences. It’s not enough to be fast, you have to be precise. You need the discipline to know exactly where your strengths lie and the courage to lean into them when it counts.
I want to walk you through how elite sprinters trade off the benefits and the risks of going out fast versus coming home strong, and what it really takes to put yourself in 46-second territory.
Going Out Fast
The Benefits
1.You establish early control.
You get clear water, away from turbulence, and you impose your rhythm on the race. The psychological edge of leading is enormous, everyone else has to respond to you.
2.You maximize pure speed.
Your ATP-PC energy system is fully charged off the blocks. You can access your highest velocity before fatigue starts to pull your stroke apart.
3. You gain a mental advantage.
Nothing breaks opponents faster than seeing you a body length ahead when they surface off the turn.
The Costs
Severe lactate accumulation.
You burn through phosphocreatine and start tapping heavily into anaerobic glycolysis. That acid build-up is coming for you on the second 50.Higher risk of deceleration.
If your conditioning isn’t world-class, your last 15 meters can fall apart spectacularly. We’ve all seen swimmers who tie up so badly that they look like they’re treading water.
Stroke mechanics under threat.
When fatigue peaks, tempo can drop 10–15%. Your line gets wobbly, your catch slips, and you lose precious tenths of a second.
Examples:
Cesar Cielo (46.91)
1st 50: 22.17
2nd 50: 24.74
Strategy: Blazing front half, then hanging on with just enough endurance to get to the wall.
James Magnussen (47.10)
1st 50: 22.83
2nd 50: 24.27
Strategy: Fast but more balanced. He relied on a huge closing 15 meters to finish over the top of people.
Coming Home Fast:
The Benefits
1. More even pacing.
A controlled first 50 helps you maintain stroke length and rhythm when the field starts to decelerate.
2. Less drop-off in speed.
Because you don’t flood your system early, you can hold a smaller positive split and finish stronger.
3. Better mechanics under fatigue.
By delaying peak lactate until the final 25 meters, you stay composed and efficient longer.
The Costs
Risk of falling too far behind.
If you’re a half body length down at the turn, you need exceptional back-half speed to catch up. That’s a lot of pressure.Mental strain.
Chasing forces many swimmers to rush their stroke or over-rotate trying to close the gap.
It requires supreme confidence.
You have to trust your plan completely and believe your finish will carry you past the field.
Example:
Kyle Chalmers
Known for being calm when he’s down early.
He trusts his closing speed more than anyone, and he’s proven it works at the highest level.
The Target: 46.40
Today, Pan Zhanle holds the standard with his 46.40 from the Paris Olympics. His splits tell the whole story:
First 50: 22.28
Second 50: 24.12
That’s the gold standard of controlled aggression. He didn’t just blast and fade, he led wire to wire and still closed in 24-low. It proves that to break the record, you need both ends of the race at an elite level.
Going Out Fast (Target: ~22.2–22.4)
Benefits
You get ahead early, like Pan did.
You fully exploit your ATP-PC burst before fatigue kicks in.
You put your competitors under immediate psychological pressure.
Costs
You accelerate lactate buildup.
Your mechanics risk collapse over the final 15 meters.
You need absolute conditioning and mental resilience to survive.
Closing Strong (Target: ~24.1–24.4)
Benefits
You preserve stroke mechanics and length, just like Pan’s textbook 24.12 back end.
You limit deceleration and avoid a major positive split.
If your first 50 is controlled, you can finish with authority.
Costs
If you’re too conservative early, you may never get back in the race.
The pressure to close forces perfect execution under fatigue.
How Popovici Shows a Different Blueprint
David Popovici’s 46.71 is a masterclass in back-half dominance:
First 50: 22.73
Second 50: 23.98
Notice that? His back-end is actually faster than Pan’s. He doesn’t have Pan’s explosive first 15 meters, and his flat-start 50 isn’t world class, he’s only around 21.8. But his strategy is to stay relaxed, stay long, and throttle up when everyone else is dying.
If you coach an athlete like Popovici, you have to build enormous aerobic capacity and the mental fortitude to trust the plan, no matter what happens in the first lap.
The Cost/Benefit Trade-Off
If you want any chance at 46.40, you need controlled aggression on the front end—pushing into the 22.2–22.4 range without crossing the line into recklessness. Then you must throttle into the second 50, hold your line, maintain your tempo, and minimize the deceleration. Pan’s 24.12 close shows exactly what that looks like when you get it right.
What I Tell My Athletes
First 50:
Attack into that 22.3–22.4 zone. Be assertive but don’t exhaust yourself. You should feel powerful, not frantic.
Turn and Transition:
Stay long, smooth, and patient off the wall. The turn is where you reset your tempo and prepare for the sprint home.
Second 50:
Hold your tempo and stroke length. This is where most races are lost, not won. Your job is to close in 24-low while everyone else falls apart.
Total:
That’s how you find yourself in world-record territory.
Final Thoughts
You need both a powerful front half and an unyielding back half. If you go out too hard and pop, you’re done. If you go out too easy and get buried, you’ll never claw it back.
Understand the cost. Understand the benefit. Then train with that clarity every single day. Because nobody in history has ever touched 46.4 by accident.
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