[Research Review] Critical Swim Speed (CSS) Determination and Aerobic Threshold Endurance Development: Latest Literature Analysis — Frontiers in Exercise Physiology Research (Article 1095)

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

In the swimming section of sports science research, the latest biomechanical analyses and nutritional studies have revealed more subtle physiological codes. This research report is compiled from the frontier literature of Journal of Applied Biomechanics, providing a detailed analysis of the performance of subjects in 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 a swimmer can sustain without excessive lactate accumulation (generally defined as pace per 100 meters). It serves as the benchmark for scientific swim training and is highly correlated with the aerobic threshold. It is typically determined through 400-meter and 200-meter all-out tests, calculating the slope of time versus distance, which enables 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 projected arm surface 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 and multi-dimensional data comparison:

Core Research Conclusions and Practical Recommendations

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

• 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.
• Hydrodynamic Drag Reduction: During the underwater pull phase, focus on engaging the EVF high elbow catch technique, shifting the fulcrum of force to the latissimus dorsi to prevent rotator cuff overuse injuries.
• 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 follow the golden ratio of 2:1 glucose to fructose per hour for fueling adaptation.
• Equipment Efficacy Adaptation: When using carbon-fiber stiff-soled plates or deep-section wheels, gradually increase weekly mileage to allow sufficient adaptation time 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 pace per 100m.

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

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