Most swimmers treat the 100m freestyle as a simple proposition: dive in, go as hard as you can, try not to die on the way back. And while it is certainly the most explosive event most age group swimmers will race, there is a lot more tactical thinking involved than people realise.
Get the pacing wrong and you tie up badly over the last 25m, watching swimmers you were ahead of at the turn come past you in the final metres. Get it right and you finish with controlled speed, a clean second lap, and a personal best.
Here is how to think about pacing the 100 free at every level.
The Basics: What Makes the 100 Free Different
Unlike the 200m freestyle, where you have four laps to manage your effort, the 100 free is just two laps. There is much less room for error. A pacing mistake in the 200 might cost you the last 50m. A pacing mistake in the 100 will cost you the last 25m, which is exactly where most races are decided.
The 100 free is what coaches call a hybrid event. It is not a pure sprint like the 50m, and it is not an endurance event like the 400m. It sits in between, which means it demands both explosive power off the start and enough controlled speed endurance to hold your stroke together over the back half.
For Younger and Beginner Swimmers: Controlled Aggression
The most common mistake younger swimmers make in the 100 free is treating it exactly like a 50m race. They explode off the blocks, sprint the first length flat out, hit the turn, and then fall apart over the final 25m.
The simple fix is this: your first 50m should feel hard but controlled. If you are sprinting at 100 percent off the start, you are going too hard. Think of it as 90 to 95 percent effort on the way out, saving just enough to hold your form and your speed on the way back.
A few practical markers for younger swimmers:
- If your second 50m is more than 5 seconds slower than your first, you went out too hard. That is the number to work on in training.
- Your turn is crucial. A tight, fast turn carries speed into the back half. A sloppy turn bleeds it away exactly when you need it most.
- Your kick matters more in the 100 than in any other event. A strong, continuous kick through the final 25m is what separates swimmers who hold on from swimmers who tie up.
For Club Swimmers: Understanding the Two-Second Rule
Research analysing thousands of performances from elite international competitions found that the 100m freestyle is almost always swum as a positive split — meaning the first 50m is faster than the second 50m. This is simply the nature of the event. You go out hard and then try to hold as much of that speed as possible on the way back.
What the data consistently shows is that elite male swimmers average around a 2 second difference between their first and second 50m splits. Elite women are slightly more even, averaging closer to a 1.9 second difference.
For club swimmers, here is a useful target range by ability:
- Beginner to age group: A 3 to 5 second split differential is normal and nothing to panic about. Work on closing that gap over time.
- Developing club swimmer: Aim to get your split differential under 3 seconds. This is where technique and speed endurance start to come together.
- Competitive club level: A differential of 1.5 to 2.5 seconds is the target. This is where you are racing efficiently.
If your differential is consistently over 5 seconds, it is a training issue more than a race day issue. It means your aerobic base or your speed endurance needs work.
The Third 25m: Where Races Are Actually Decided
This is one of the most important things any coach can tell a 100m freestyler. Research analysing elite performances has found that the third 25m segment (the first 25m of the return lap, immediately after the turn) is more predictive of final race ranking than any other segment of the race — including the start and the first 50m.
Think about what happens at that point in the race. You have just turned. Your lungs are burning. Lactic acid is building. Your stroke wants to break down. The swimmers who can hold their speed, their technique, and their kick through this specific 25m are the ones who end up on the podium.
Practically, this means your training should specifically target the third 25m. Sets that simulate that moment of fatigue mid-race, and force you to hold your stroke and your speed through it, are worth their weight in gold for 100m freestyle performance.
For Serious Swimmers: What Pan Zhanle’s World Record Tells Us
The Paris 2024 Olympic final in the men’s 100m freestyle is one of the most instructive race performances in the history of the event. Pan Zhanle of China swam a world record of 46.40, breaking his own previous world record by 0.40 seconds and winning by over a full second in a field where all eight finalists went under 48 seconds for the first time in Olympic history.
What made Pan’s swim extraordinary from a pacing perspective was that he swam both the fastest opening split and the fastest closing split in the entire field. He did not just go out hard and hang on. He went out hard and came back harder.
His winning split: 22.28 for the first 50m, 24.12 for the second 50m. A differential of 1.84 seconds at world record pace.
Compare that to France’s Maxime Grousset, who had one of the fastest first 50m splits in the field but faded badly on the return and finished out of the medals. The pattern is consistent with what research shows: the swimmers with the largest split differentials tend to finish lower in the standings, regardless of how fast their opening 50m was.
Popovici, who took bronze in 47.49, also closed well. The top three finishers all had tighter split differentials than the swimmers who finished behind them. Controlled aggression from the start, and the capacity to hold speed through the back half, is what separates the medallists from the rest of the field even at the highest level in the world.
How to Train for Better 100m Freestyle Pacing
A few specific sets worth building into your training:
- Broken 100s: Swim 75m at race pace, rest 10 seconds at the wall, then finish the final 25m as fast as possible. This isolates the back end of the race and trains your body to produce speed under fatigue.
- 25m pace sets: Swim 8 x 25m on a short rest interval, targeting your goal race pace for each one. If you cannot hold your pace on reps 6, 7, and 8, your speed endurance needs work.
- Race simulation: Swim a 100m in training where you deliberately go out 1 second slower than race pace on the first 50m, then try to negative split the race. Most swimmers find this incredibly difficult. That difficulty is exactly what you are training.
- Underwater work: Since the turn and underwater off each wall directly impacts your third 25m speed, dedicated underwater sets are some of the most specific training you can do for the 100 free.
A Final Note
The 100m freestyle rewards what I call controlled aggression. You cannot be timid off the start and expect to win the race on the back half. But you also cannot treat it as a 50m sprint and expect to hold together when your lungs are screaming at you through that third 25m.
Find that balance in training, and race day takes care of itself.
At Vineyard Swimming we work on race-specific pacing from the age group level upwards. If you want to know more about how we approach sprint training in Cape Town, get in touch at Duncan@VineyardSwimming.co.za.
About Duncan Bonney
Duncan Bonney is an ASCA Level 4 and Swim SA Level 2 certified swim coach based in Cape Town, with over 10 years of experience coaching swimmers from beginner level through to SA Nationals. He manages Vineyard Swimming and has helped multiple athletes secure overseas university swimming scholarships. Read more about Duncan Bonney, connect on LinkedIn, or follow on X.