It is estimated 85% to 90% of propulsion generation in water is created by the application of force by an arm (Descholdt 1999; Hollander 1988). Studies have suggested the order of propulsion is greatest by the hand, followed by the forearm, then the shoulder (Miller 1975). In fact, the hand is believed to created 2.5 times the hydrodynamic force as the forearm (Miller 1975).
Now, many still debate specific stroke biomechanics and the true role of propulsion in freestyle. No matter your stance, it is hard to deny certain joint angles change during freestyle to diminish drag and maximize propulsion. For example, the shoulder joint goes through various angles of abduction, flexion, and adduction for ideal performance.
The ideal position of the fingers for creating force has been studied previously. Marinho (2010) used computational fluid dynamics (CFD) and noted swimming with the fingers spread produced more force and with the fingers together (see Finger Spread and Propulsion). More recently, Bilinauskaite (2013) performed similar CFD analysis and noted the largest mean of drag force was noted in the thumb adducted (see figure-1) group during the pull phase. Yet, the other hand positions had larger mean drag force during the push phase.
Bilinauskaite (2013) study suggests the finger changes drag coefficients during different phases of the stroke. However, coaches rarely discuss changing finger position throughout the propulsive phase of freestyle.
Many argue CFD analysis is not applicable to real-life swimming and using the CFD of one elite swimmer is far from perfect, but but the idea of dynamic finger positions during the propulsive phase must be considered.
Differently phases of the stroke require higher or lower drag for optimization. Swimmers should consider altering their finger position throughout their stroke to maximize propulsion and drag during the stroke. Specifically, during the initial catch, a thumb adducted position during the entry until the catch phase occurs, then a transition to finger spread and thumb abduction should be considered.
However, altering finger position and propulsion surfaces must be directed in the correct position. Therefore, these subtle adjustments are only beneficial for swimmers with correct joint positioning.
- Bilinauskaite M, Mantha VR, Rouboa AI, Ziliukas P, Silva AJ. Computational Fluid Dynamics Study of Swimmer’s Hand Velocity, Orientation, and Shape: Contributions to Hydrodynamics. Biomed Res Int. 2013;2013:140487. doi: 10.1155/2013/140487. Epub 2013 Apr 9.
- J. V. Deschodt, L. M. Arsac, and A. H. Rouard, “Relative contribution of arms and legs in humans to propulsion in 25- m sprint front-crawl swimming,” European Journal of Applied Physiology and Occupational Physiology, vol. 80, no. 3, pp. 192– m199, 1999.
- A. P. Hollander, G. de Groot, G. J. van Ingen Schenau, R. Kahman, and H. M. Toussaint, “Contribution of the legs in front crawl swimming,” in Swimming Science V, B. E. Ungerechts, K. Reischle, and K. Wilke, Eds., pp. 39–43, Human Kinetics Publishers, Champaign, Ill, USA, 1988.
- D. I.Miller, “Biomechanics of swimming,” in Exercise and Sport Sciences Reviews,H.Willmore and J. F. Keogh, Eds.,pp. 219–248, Academic Press, New York, NY, USA, 1975.
- D. A. Marinho, T. M. Barbosa, V. M. Reis et al., “Swimming propulsion forces are enhanced by a small finger spread,” Journal of Applied Biomechanics, vol. 26, no. 1, pp. 87–92, 2010.