Swimmers' Video Training: Practical Applications of Underwater Video Analysis

Introduction

“Your entry angle is off”—the coach has said it dozens of times from the pool deck, but the swimmer simply cannot feel what is wrong. This is a common dilemma in competitive swimming training: the limitations of proprioception prevent swimmers from accurately assessing their own movements.

Underwater video analysis is precisely the most effective tool for solving this problem. It allows swimmers to “see themselves swim” for the first time, and through objective footage, identify technical issues that are difficult to detect during training.

Why Is Underwater Video More Important Than Surface Video?

Surface video captures the swimmer’s overall posture and breathing, but most swimming movements occur underwater: the pull path, kick pattern, wall push-off angle during turns, and the glide position after the start dive. Without underwater footage, coaches and swimmers are only seeing “half the story.”

Core advantages of underwater video:

• Visualizing the pull path: high-elbow catch, completeness of the push phase
• Kick efficiency analysis: kick rate, knee bend angle, ankle range of motion
• Streamline posture check: body angles that minimize drag
• Start dive entry angle: a key factor in underwater glide efficiency
• Turn breakdown: optimizing wall push-off force and angle

Standard Workflow for Underwater Video Analysis

Step 1: Filming Setup

It is recommended to use a waterproof camera (such as the GoPro series) mounted on the pool wall, or use a professional pool with viewing windows.

Step 2: Video Marking and Quantification

Raw footage alone has limited value; it must be paired with quantitative analysis:

• Stroke Rate: number of complete stroke cycles per minute
• Distance Per Stroke: distance traveled per stroke cycle
• Stroke Index: speed × distance per stroke (the higher the value, the better the efficiency)
• Kick rate and amplitude: kicks per second and knee bend angle

Step 3: Comparative Analysis

The value of a single recording session is limited. True progress tracking comes from “temporal comparison”:

• Before training vs. after training (after 2–4 weeks of corrections)
• Differences in movement between fatigued and rested states
• Technical comparison between the swimmer’s current movement and a reference swimmer (e.g., Olympic-level demonstration footage)

Step 4: Correction Plan and Follow-up

Once issues are identified, a specific technical correction plan must be developed:

• Technical focus for each training session (no more than 2 items)
• Auxiliary drills (e.g., pull buoy, kickboard isolation drills)
• Re-record after 4 weeks to confirm the effectiveness of corrections

Practical Difficulties for Grassroots Coaches in Taiwan

Many grassroots swim teams in various counties and cities lack professional underwater filming equipment and analysis software. Here are low-cost alternatives:

• GoPro Hero series + poolside mounting bracket: total cost approximately NT$8,000–15,000
• Free analysis software: Kinovea (PC) or the CoachMyVideo app (mobile), offering frame-by-frame playback and angle measurement
• Systematic filming 1–2 times per month: no need to record every session; the key is accumulating a time-series for comparison

Practical Recommendations

1. Build a personal video archive for each swimmer: attach the date and training cycle markers to every recording
2. Let swimmers watch and identify problems themselves: self-discovery is more convincing than coach explanations
3. Combine surface video with underwater video: gain a complete understanding of overall movement
4. Avoid correcting too many issues at once: focus on 1–2 technical points per correction cycle
5. Compare technical condition before and after competitions: understand how race fatigue affects technique

Conclusion

Video training is not a high-tech luxury; it is a fundamental tool in modern competitive swimming. When swimmers see their underwater movements for the first time, that shock of “so that’s how I swim” is often the starting point of technical breakthroughs. Making good use of underwater video analysis to evolve training from “feel-driven” to “data-driven” is an important step in raising Taiwan’s competitive swimming standards.

Related Reading

• Swimming Video Analysis: Key Observations for Surface and Underwater Filming
• Swimming Technique Video Analysis: How to Use Underwater Filming to Identify Your Own Flaws
• Self-Analysis Through Swimming Video: Technical Diagnostic Methods for Surface and Underwater Filming
• Post-Race Swimming Performance Analysis: A Systematic Approach to Identifying Technical Errors Through Video Review