Pacing the First and Second Halves of a 100m Freestyle Swim: A Split Analysis of the World Record

Introduction

The 100m freestyle is hailed as “the 100m sprint of swimming,” combining explosive power, technique, and pacing judgment. In international competitions, it is often one of the most anticipated events, with spectators’ eyes locked on every moment from the start to the touch of the wall. However, in this race lasting less than a minute, how to distribute energy between the first and second halves is often the key to victory or defeat.

Split Data of World-Class Swimmers

Taking the men’s 100m freestyle in a long course (50m) pool as an example, the split pacing of elite swimmers roughly follows this pattern:

World-class male swimmers (46–47 second level) typically complete the first 50m in 22–23 seconds and the second 50m in 24–25 seconds, showing a “slightly positive split”—the first half is slightly faster, the second half slightly slower, but the difference is kept within 1.5–2.5 seconds. If the second half is clearly more than 3 seconds slower, it usually indicates excessive sprinting in the first half and overly rapid lactate accumulation.

Comparison of Three Pacing Strategies

1. Positive Split

Fast first half, slow second half—this is the natural pacing tendency of most non-elite swimmers. Driven by adrenaline and the race atmosphere, swimmers often push too hard at the start, leading to a collapse in the second half.

2. Even Split

The first and second halves are nearly identical in time, indicating that the swimmer’s sense of pace and energy distribution is highly precise. For some swimmers, this is the ideal model, but over a 100m all-out sprint distance, a near-perfect even split is actually uncommon.

3. Negative Split

The second half is faster than the first half. In short-distance swimming, a purely negative split is rare because the first half includes the “free speed” from the dive and starting propulsion, which is inherently faster than the second half. However, strategically, swimmers can still choose to “hold back conservatively” in the first half, making the second half relatively more competitive.

Three Key Elements of the First 50m

1. Reaction Time: World-class swimmers typically have a reaction time of 0.60–0.70 seconds, while Taiwanese swimmers average around 0.70–0.80 seconds. Every 0.05-second improvement in reaction time has a direct impact on the final result.
2. Entry Angle and Underwater Dolphin Kick: An entry angle that is too steep (excessive splash) or too flat (increased drag) will lose kinetic energy. The ideal underwater dolphin kick after entry is about 4–6 kicks, not exceeding 15 meters at most.
3. Establishing the Rhythm of the First Strokes: The first 3–4 strokes after surfacing determine the entire stroke rhythm. If the rhythm is too fast, lactate accumulation will accelerate; if too slow, the early speed advantage of the race is lost.

Lactate Management in the Second 50m

• Speed Reset After the Turn: The turn is an important “recharging station” for the second half. A well-executed turn allows swimmers to regain their rhythm after a brief anaerobic push.
• Adjusting Breathing Frequency: Many swimmers unconsciously increase their breathing frequency when facing oxygen debt in the second half, but overly frequent breathing actually disrupts stroke rhythm and reduces speed. It is recommended to maintain the breathing rhythm set in the first half until the finish line.
• Maintaining Hip Position: Under fatigue, the hips tend to sink, increasing water resistance. Consciously maintaining a horizontal body position is a key technical point for sustaining speed in the second half.

Practical Recommendations

1. Deliberately train second-half ability in practice: Use “Descending Sets,” such as 4×100m continuously, with each rep’s second half 2 seconds faster than the first half, to train the body’s sense of acceleration in the latter part.
2. Use a stopwatch to record 50m splits: Immediately record the 50m and 100m times after each 100m practice, tracking the first-half/second-half gap over the long term, with the goal of keeping the difference within 2 seconds.
3. Simulate first-half race intensity: Incorporate mixed training of “all-out first half, technical control in the second half” into practice, teaching the body to maintain stroke efficiency after high-intensity effort.
4. Study your own lactate threshold: Work with your coach to understand your anaerobic threshold speed through lactate testing, using it as the upper limit reference for first-half race pace.

Conclusion

The pacing strategy for the 100m freestyle may seem simple, but it embodies a philosophy of refined energy management. A slightly positive split is the mainstream choice among world-class swimmers, but each swimmer’s optimal pacing pattern differs slightly, and it takes long-term accumulation of training data to find one’s own “best rhythm.” Understanding the meaning of split data and consciously practicing pace control in training is an important step from being an amateur swimmer to reaching competitive standards.

Related Reading

• Pacing Analysis of the 100m Freestyle: Optimal First-Half/Second-Half Distribution Ratio and Its Impact on Performance
• 100m Freestyle Pacing: The Science of Time Distribution Between the First and Second Halves
• 50m Freestyle Split Strategy: The Optimal Ratio of the First 15m, Middle Maintenance, and Final Sprint
• Swimming Race Split Pacing Strategies: First-Half/Second-Half Ratios for 50m, 100m, 200m, and 400m