I Analysed 200 Swimmers: The Most Common Swim Technique Errors

I Analysed 200 Swimmers: The Most Common Swim Technique Error

Over the past year, I’ve carried out more than 200 swim analysis sessions in London with swimmers ranging from novice triathletes to experienced IronMan athletes and competitive swimmers. Despite major differences in pace and experience, the same swim technique errors appeared again and again.

These patterns were not occasional, they were consistent across the majority of swimmers.

Rotation Is Consistently Below Optimal Levels (75–80%)

Approximately 3 out of 4 swimmers demonstrated suboptimal rotation.

Typical observations:

• Rotation between 20–40 degrees

• Asymmetry between breathing and non-breathing sides

• Loss of rotation mid-stroke
  

For example:

• Functional but limited rotation

• Clear asymmetry linked to breathing patterns 
  

This matters because reduced rotation leads to:

• Shorter stroke length

• Poor catch positioning

• Increased reliance on the shoulders
  

Key takeaway: Rotation is one of the most common and most limiting technical factors.

Body Position Issues Appear in 85% of Swimmers (But Rarely as the Root Cause)

Around 80–85% of swimmers showed some form of body position inefficiency:

• Hips sitting slightly low

• Legs dropping

• Front-end instability

In the majority of cases, this was not caused by head position alone. Even swimmers with good alignment still experienced body position breakdown due to:

• Poor propulsion

• Incorrect timing

• Loss of front-end support
  

Key takeaway: Body position is not the primary fault; it is the result of other inefficiencies.

Entry Errors Occur in 70–80% of Swimmers

Hand entry was one of the most consistent sources of error.

Across the dataset, approximately 3 out of 4 swimmers showed at least one of the following:

• Short entry

• Entry crossing the centre line

• Thumb-first or steep entry angle

• Immediate downward “harpooning”

Examples:

• Short, unstable entry patterns 

• Crossed or misaligned entry 

These issues directly affect:

• Stroke balance

• Catch timing

• Drag at the front of the stroke
  

Key takeaway: Entry is a primary determinant of stroke quality and often the starting point of inefficiency.

Catch Inefficiency Appears in 75% of Swimmers (But is usually misdiagnosed)

Approximately 70–75% of swimmers showed ineffective catch mechanics.

The underlying issue was rarely strength or effort.

Instead:

• Catch initiated too deep (often 15–30cm below surface)

• Lead hand dropping early

• Reduced ability to hold water

Examples:

• Deep catch linked to entry mechanics 

• Loss of front-end stability 
  

Key takeaway: Catch problems are usually setup problems, not execution problems.

Kick Is Non-Propulsive in 80–90% of Swimmers

Across the dataset:

• The majority of swimmers generated minimal propulsion from the kick

• Kick was primarily used for balance and timing
  

Observed patterns:

• Poor synchronisation with arm entry

• Excessive effort with limited return

• Compensatory kicking due to instability
  

Examples:

• Efficient but low-propulsion kick 

• Over-reliance on kick for balance 
  

Key takeaway: For most swimmers, the kick supports the stroke, it does not drive it.

Breathing Disrupts Stroke Mechanics in 65–75% of Swimmers

Breathing was not typically the primary issue, but it exposed underlying faults.

Approximately two-thirds of swimmers showed:

• Head lift instead of rotation

• Lead hand drop during breathing

• Breakdown in stroke timing
  

Examples:

• Breathing timing affecting control 

• Structural breakdown during breath phases 
  

Key takeaway: Breathing highlights inefficiencies rather than creating them.

Multiple Faults Occur in Combination (Average: 3–4 Per Swimmer)

Perhaps the most important finding:

The average swimmer presented with 3–4 interacting technical faults.

Common combinations included:

• Short entry → deep catch → poor propulsion

• Limited rotation → wide recovery → crossover

• Timing issues → instability → over kicking

Key takeaway: Swimming inefficiency is rarely caused by a single issue.

Conclusion

Across approximately 200 swimmers, the same technical patterns appeared with high consistency:

• 80% showed suboptimal rotation

• 85% showed body position inefficiencies

• 75% showed entry and catch-related issues

• 80–90% relied on the kick for balance rather than propulsion
  

These patterns were observed across all ability levels. Performance in the water is constrained less by fitness and more by technical efficiency.

Improvement should therefore prioritise:

• Rotation

• Entry mechanics

• Stroke timing
  

These changes produce the greatest downstream impact across the stroke. You can find out more about our swim analysis in London, including the cost and availability by clicking the link.