Research Progress of Swimming Drag Reduction and Propulsion Technology Optimization

To summarize the research literatures of swimming drag reduction and propulsion technical optimization in recent20 years. For the aspect of swimming drag reduction, the wave resistance of 0.6~1.0 m underwater can be ignored, and the gliding at different speeds under this condition has a certain distance and time advantage than that of the water-surface gliding; the underwater dolphin kick of lateral streamlined positions is better than dorsal and ventral streamlined positon, and the overlapping of hands in front of the head will slightly offset the center of gravity of the body; abdominal breathing is better than chest breathing before underwater sliding; head-middle position reduces total drag by 4% compared to head-up position; the total resistance value of inverted triangle shape is better than that of inverted trapezoid, rectangle and ellipse, and the additional weight of female swimmers is less than that of men; in open-water swimming; the closer between draft swimmer and leader swimmer will lead to a better drag reduction effect, and the drag reduction effect is different when draft swimmer at different positions; the swimmer wearing 3 D swimming cap can reduce the resistance value by 6% compared with 2 D swimming cap, and the 3 D Golf concave point swimming cap has the lowest resistance value. For the aspect of increasing propulsion, the finger opening and closing and palm shape have different influences on resistance propulsion; foot is the main propulsion force of underwater dolphin kick; the frequency of underwater dolphin kick is similar among swimmers, but the kicking amplitude is different; ankle flexibility can improve the amplitude of underwater kick, but the compensation of ankle flexibility asymmetry should be considered; the forward extended arms have inertia damping effect, which can reduce the amplitude of arm up and down motion; the net resistance of left arm and right arm in crawl swimming is significantly different, but there is no significant difference in backstroke. In conclusion, the non-complex swimming movement research is a hot issue, and some research has paid attention to the resistance optimization of open water swimming. However, there are little research focus on the complete action and technical optimization based on four swimming styles. The research on the complete action and different movement speed, amplitude, frequency, rhythm and posture need more future research. China has some advantages in drag reduction and propulsion technology optimization of high-level swimmers, but it develops slowly in the field of basic research of fluid mechanics. Therefore, interdisciplinary research should be strengthened to make up for the shortcomings and deficiencies in this field.