[Research Review] Critical Swim Speed (CSS) Determination and Aerobic Threshold Endurance Development: Latest Literature Analysis on Elite Athlete Physiological Characteristics (Article 360)

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

In the swimming section of sports science, the latest biomechanical analyses and nutritional research have revealed more subtle physiological codes. This research report is compiled from cutting-edge literature in the 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 cruising pace (generally defined as pace per 100 meters) that a swimmer can sustain 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 workouts.

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 biomechanical experiment analyzed the swimmer’s forearm projected area and shoulder joint torque during the underwater pull phase. The results found that EVF allows swimmers to orient the forearm and hand perpendicular to the water flow during the first half of 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, substantially reducing the load on the deltoid muscles of the shoulder.

Comparative Table of Mechanical Efficiency: High Elbow Catch (EVF) vs. Straight-Arm Pull

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

Core Scientific Conclusions and Practical Recommendations

Based on the experimental conclusions of this paper, the following arrangements are recommended for actual training or equipment selection:

• Equipment Efficacy Adaptation: When using carbon-fiber stiff plates or deep-section wheels, gradually increase weekly mileage to allow the Achilles tendon and joints sufficient adaptation time.
• Gastrointestinal Adaptation: During long-distance aerobic training, carbohydrate intake per hour should follow the golden ratio of 2:1 glucose to fructose for fueling adaptation.
• Biomechanical Feedback: Strengthening the gluteus medius and deep core muscles can significantly improve pelvic tilt during the support phase, preventing uneven patellar loading under high intensity.
• Quantified Data Monitoring: It is recommended to use heart rate variability or VO₂max zones to continuously assess autonomic nervous system fatigue and overload indicators.
• Hydrodynamic Drag Reduction: During the underwater pull phase, focus on generating force through the EVF high elbow catch technique, shifting the fulcrum of force to the latissimus dorsi to prevent rotator cuff overuse injuries.

Common Scientific 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 a per-100m pace.

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

A: The straight-arm pull generates a downward force component, causing significant fluctuation in the body’s waterline which increases drag, and creates excessive frictional stress on the shoulder 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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