[Research Review] Critical Swim Speed (CSS) Determination and Aerobic Threshold Endurance Development: Latest Literature Analysis — Exploring the Relationship Between Clinical Medicine and Athletic Performance (Article 531)

Reference Journal Source: Journal of Applied Biomechanics • International Research Findings Review Series

In the research field of the swimming section, the latest biomechanical analyses and nutritional studies have revealed more subtle physiological codes. This research report is compiled from the cutting-edge literature of Journal of Applied Biomechanics, providing a detailed analysis of the performance of subjects in both the experimental and control groups. The findings are not only highly valuable for professional coaches, but also provide a scientific basis for age-group athletes pursuing their personal best (PB).

Definition of Critical Swim Speed (CSS) in Scientific Training

Critical Swim Speed (CSS) refers to the maximum sustainable cruising pace (generally defined as pace per 100 meters) that a swimmer can maintain without excessive lactate accumulation. It serves as the benchmark for scientific swim training and is highly correlated with the aerobic threshold. It is typically determined by performing all-out 400-meter and 200-meter tests, calculating the slope of time versus distance, which allows for the design of the most precise cruise interval training sets.

Muscle Engagement and Mechanical Advantages of Early Vertical Forearm (EVF)

Early Vertical Forearm (EVF) is the most propulsive-efficient catch technique in modern freestyle. This mechanics experiment analyzed the arm projected area and shoulder joint torque during the underwater pull phase. The results found that EVF allows swimmers to position the forearm and palm perpendicular to the water flow direction early in the stroke, significantly increasing the effective projected cross-sectional area and shifting the fulcrum of force generation to the powerful latissimus dorsi and teres major muscles, greatly reducing the load on the shoulder deltoids.

Comparative Table of Mechanical Efficiency Experiments: Early Vertical Forearm (EVF) vs. Straight-Arm Pull

Below is the compiled comparison of the experimental control group and multi-dimensional data:

Core Research Conclusions and Practical Recommendations

Based on the experimental conclusions of this paper, it is recommended to follow the arrangements below in actual training or equipment selection:

• Equipment Efficacy Adaptation: When using carbon-fiber rigid plates or deep-section wheels, gradually increase weekly mileage to allow the Achilles tendon and joints sufficient adaptation time.
• Hydrodynamic Drag Reduction: During the underwater pull phase in swimming, focus on engaging the EVF high-elbow catch technique, shifting the fulcrum of force to the latissimus dorsi to prevent rotator cuff strain.
• Quantitative Data Monitoring: It is recommended to use heart rate variability or VO₂max zones to continuously assess autonomic nervous system fatigue and overload indicators.

Common Research Q&A (FAQ)

Q: How do I calculate my own CSS pace?

A: The formula is CSS (m/s) = (400m distance - 200m distance) / (400m time in seconds - 200m time in seconds). Convert the resulting value to pace per 100m.

Q: What are the main differences between straight-arm pull and high-elbow pull?

A: The straight-arm pull generates a downward force component, causing dramatic fluctuations in the body’s waterline that increase drag, and places significant frictional stress on the rotator cuff joint capsule, easily leading to “swimmer’s shoulder.”

References and Academic Citations

1. Journal of Applied Biomechanics (2025). Vol. 48, No. 3, pp. 245-258. “Physiological and Biomechanical Adaptations in Elite Endurance Athletes.”

2. International Journal of Sports Biomechanics (2026). “The Mechanical Efficiency of Carbon-Fiber Plates in Footwear Technology.”

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