【Research Review】Latest Literature Analysis on Critical Swim Speed (CSS) Determination and Aerobic Threshold Endurance Development: International Research Compilation and Review Report (No. 1074)

Source Journal Reference: 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 cruising pace (generally defined as the pace per 100 meters) that a swimmer can maintain without excessive lactate accumulation. It serves as the benchmark for scientific swimming training and is highly correlated with the aerobic threshold. It is typically determined through all-out 200-meter and 400-meter tests, calculating the slope of time versus distance, which enables the design of the most precise cruising 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 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 in 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, greatly reducing the load on the deltoid muscles of the shoulder.

Comparative Table of Biomechanical Efficiency Experiments: EVF vs. Straight-Arm Pull

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

Core Research Conclusions and Practical Recommendations

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

• Hydrodynamic Drag Reduction: During the underwater pull phase, focus on the force generation of 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 maximal oxygen uptake zones to continuously assess autonomic nervous system fatigue and overload indicators.
• 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.
• Gastrointestinal Adaptation: During long-distance aerobic training, carbohydrate intake should be adapted using the golden ratio of 2:1 glucose to fructose per hour.
• Equipment Efficacy Adaptation: When using carbon-fiber stiff plates or deep-section wheels, gradually increase weekly mileage to provide sufficient adaptation periods for the Achilles tendon and joints.

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 a per-100m pace.

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

A: Straight-arm pull generates a downward force component, causing dramatic fluctuations in the body’s waterline that increase drag, and imposes 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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