Endurance Sports

Hydrodynamics: Why Technique Trumps Power in Swimming

Jan 18, 2026
10 min read

In running, more force typically equals more speed. In swimming, applying more force often just makes you tired. Why? Because water is 800 times denser than air.

The battle in the pool is not against your competitors; it is against drag. Understanding hydrodynamics is the only way to break through the "plateau of effort."

1. The Drag Equation

Drag (Resistance) increases with the square of velocity. This means to swim twice as fast, you have to overcome four times the drag. Therefore, reducing resistance is exponentially more efficient than increasing power.

  • Form Drag: Caused by the shape of the body. Dropping your hips creates a massive frontal surface area, acting like a parachute.
  • Wave Drag: Caused by turbulence at the surface. This is why elite swimmers stay underwater (streamline) as long as legally possible off the walls.
  • Frictional Drag: The interaction between skin/suit and water. This is why pros shave down and wear tech suits.

2. Body Position: The Vessel

Imagine your body is a vessel. A submarine moves faster than a barge. Most beginners swim "uphill"—head up, hips down. This increases form drag significantly.

The Teeter-Totter Effect

Your lungs are the fulcrum. If you lift your head to breathe, your hips sink. The goal is to press the "T" (chest) down, elevating the hips and legs to the surface. A horizontal body line is non-negotiable for speed.

3. Propulsion: Hold the Water

Don't think about pulling your hand through the water. Think about anchoring your hand in the water and pulling your body past it. This is the concept of Early Vertical Forearm (EVF).

If you drop your elbow, you are "petting the cat"—applying force downwards rather than backwards. A high elbow catch increases the surface area (hand + forearm) acting as a paddle blade.

4. Rotation and Torque

A flat swimmer is a slow swimmer. Power in freestyle comes from hip rotation, not shoulder strength. By rotating 45 degrees to each side, you engage the lats and core, accessing the body's largest muscle groups. This also reduces shoulder impingement, saving your rotator cuffs from injury.

5. Measuring Efficiency: SWOLF

SWOLF (Swim Golf) is a metric used to measure efficiency.SWOLF Score = Time (seconds) + Stroke Count (per length).

A lower score is better. If you swim 25m in 20 seconds with 20 strokes, your SWOLF is 40. If you muscle through it in 18 seconds but take 26 strokes (SWOLF 44), you became faster but less efficient. The goal is to lower your time while maintaining or lowering your stroke count.

Conclusion

Swimming is a skill-based sport masquerading as a fitness activity. Before you do another 400m hard set, stop and drill. Fix your body line. Reduce drag. Be like water, my friend.

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