Tiago J. Lopes^1,2, Tatiana Sampaio^1,2,3, Mafalda P. Pinto^1,2, João P. Oliveira^1,2,3, Daniel A. Marinho^1,2, Jorge E. Morais^4,3

¹Department of Sport Sciences, University of Beira Interior, Covilhã, Portugal
²Research Centre in Sports, Health and Human Development (CIDESD), Covilhã, Portugal
³Research Centre for Active Living and Wellbeing (LiveWell), Instituto Politécnico de Bragança, Bragança, Portugal
⁴Department of Sport Sciences, Instituto Politécnico de Bragança, Bragança, Portugal

Comparison of the Active Drag and Passive Drag Coefficients at the same Swimming Speed Through Experimental Methods

Monten. J. Sports Sci. Med. 2025, 14(1), 81-86 | DOI: 10.26773/mjssm.250309

Abstract

Studies about drag in swimming usually report or put the focus on its absolute value. However, it is being claimed that the drag coefficient better represents the hydrodynamic profile of a swimmer. Drag is strongly dependent on speed. Thus, increases in speed will lead to increases in drag. This could lead to misleading interpretations since drag is the water resistance that makes the swimmers’ displacement difficult. Conversely, the drag coefficient is less dependent on speed, which can be seen as a more appropriate measure of the swimmers’ hydrodynamic profile. This study used a complete experimental methodology (experimental and cross-sectional study) to determine the resistive forces in crawl swimming at the same speed (i.e., 1.00, 1.05, 1.10 m/s, etc.). In 10 proficient non-competitive adult swimmers (seven men and three women), the drag coefficient (CD) was compared and the difference between using the technical drag index (TDI) with drag (D, passive or active) or with its respective CD 's. Measurements of active drag (DA), passive drag (DP) and CD (CDA and CDP) were carried out. The TDI was calculated as a measure of swimming efficiency and the frontal surface area (FSA) obtained in active conditions. The active FSA was 20.73 ± 5.56% greater than the passive FSA (large effect size), the propulsion was 58.29 ± 69.61% greater than drag and CDA was 24.60 ± 46.55% greater than CDP (moderate effect size). TDI was significantly lower, but with a small effect size when measured with CD values compared to drag. TDID vs TDICD revealed strong agreement (> 80% of plots were within IC95). This study concludes that proficient swimmers presented a CDA greater than the CDP, but with strong agreement between them, probably due to FSA during active conditions. CD data appears to be a more absolute indicator of drag than TDI.

Keywords

human body, practical methodology, resistive forces, biomechanics, technique

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References

Barbosa, T. M., Costa, M. J., Morais, J. E., Morouço, P., Moreira, M., Garrido, N. D., Marinho, D. A. & Silva, A. J. (2013). Characterization of speed fluctuation and drag force in young swimmers: A gender comparison. Human Movement Science, 32(6), 1214–1225. https://doi.org/10.1016/j.humov.2012.07.009.

Berger, M. A. (1999). Determining propulsive force in front crawl swimming: A comparison of two methods. Journal of Sports Sciences, 17(2), 97–105. https://doi.org/10.1080/026404199366190.

Bland, J. M., & Altman, D. (1986). Statistical methods for assessing agreement between two methods of clinical measurement. The lancet, 327(8476), 307-310. https://doi.org/10.1016/s0140-6736(86)90837-8.

Cortesi, M., Gatta, G., Carmigniani, R., & Zamparo, P. (2024). Estimating active drag based on full and semi-tethered swimming tests. Journal of Sports Science and Medicine, 23(1), 17–24. https://doi.org/10.52082/jssm.2024.17.

Gatta, G., Cortesi, M., Fantozzi, S., & Zamparo, P. (2015). Planimetric frontal area in the four swimming strokes: Implications for drag, energetics and speed. Human Movement Science, 39, 41–54. https://doi.org/10.1016/j.humov.2014.06.010.

Gatta, G., Cortesi, M., & Zamparo, P. (2016). The relationship between power generated by thrust and power to overcome drag in elite short distance swimmers. PloS One, 11(9), e0162387. https://doi.org/10.1371/journal.pone.0162387.

Gatta, G., Zamparo, P., & Cortesi, M. (2013). Effect of swim cap model on passive drag. Journal of Strength and Conditioning Research, 27(10), 2904–2908. https://doi.org/10.1519/jsc.0b013e318280cc3a.

Havriluk, R. (2007). Variability in measurement of swimming forces. Research Quarterly for Exercise and Sport, 78(2), 32–39. https://doi.org/10.1080/02701367.2007.10599401.

Hopkins, W. G. (2019). A scale of magnitudes for effect statistics. A new view of statistics. 2002. Internet http://sportsci.org/resource/stats/effectmag.html (10 October 2013).

Kjendlie, P. L., & Stallman, R. K. (2008). Drag characteristics of competitive swimming children and adults. Journal of Applied Biomechanics, 24(1), 35–42. https://doi.org/10.1123/jab.24.1.35.

Kolmogorov, S. V., & Duplishcheva, O. A. (1992). Active drag, useful mechanical power output and hydrodynamic force coefficient in different swimming strokes at maximal velocity. Journal of Biomechanics, 25(3), 311–318. https://doi.org/10.1016/0021-9290(92)90028-y.

Lopes, T. J., Morais, J. E., Pinto, M. P. & Marinho, D. A. (2022). Numerical and experimental methods used to evaluate active drag in swimming: A systematic narrative review. Frontiers in Physiology, 13, 938658. https://doi.org/10.3389/fphys.2022.938658.

Lopes, T., Sampaio, T., Oliveira, J. P., Pinto, M. P., Marinho, D. A. & Morais, J. E. (2023). Using wearables to monitor swimmers’ propulsive force to get real-time feedback and understand its relationship to swimming velocity. Applied Sciences, 13(6), 4027–4027. https://doi.org/10.3390/app13064027.

Morais, J. E., Barbosa, T. M., Garrido, N. D., Cirilo-Sousa, M. S., Silva, A. J., & Marinho, D. A. (2023). Agreement between different methods to measure the active drag coefficient in front-crawl swimming. Journal of Human Kinetics, 86(1), 41–49. https://doi.org/10.5114/jhk/159605.

Morais, J. E., Marinho, D. A., Bartolomeu, R. F. & Barbosa, T. M. (2024). Understanding the importance of drag coefficient assessment for a deeper insight into the hydrodynamic profile of swimmers. Journal of Human Kinetics, 92. https://doi.org/10.5114/jhk/172492.

Morais, J. E., Sanders, R. H., Papic, C., Barbosa, T. M., & Marinho, D. A. (2020). The influence of the frontal surface area and swim velocity variation in front crawl active drag. Medicine and Science in Sports and Exercise, 52(11), 2357–2364. https://doi.org/10.1249/mss.0000000000002400.

Narita, K., Nakashima, M. & Takagi, H. (2017). Developing a methodology for estimating the drag in front-crawl swimming at various velocities. Journal of Biomechanics, 54, 123–128. https://doi.org/10.1016/j.jbiomech.2017.01.037.

Pendergast, D. R., Capelli, C., Craig, A. B., di Prampero, P. E., Minetti, A. E., Mollendorf J., Termin, I. I., & Zamparo, P. (2006). Biophysics in swimming. In, Vilas-Boas JP, Alves F, Marques A (editors). Biomechanics and Medicine in Swimming X. Porto: Portuguese Journal of Sport Science, 185-189.

Scurati, R., Gatta, G., Michielon, G., & Cortesi, M. (2019). Techniques and considerations for monitoring swimmers’ passive drag. Journal of Sports Sciences, 37(10), 1168–1180. https://doi.org/10.1080/02640414.2018.1547099.

Toussaint, H. M., & Beek, P. J. (1992). Biomechanics of competitive front crawl swimming. Sports Medicine, 13, 8-24.

Vilas-Boas, J. P., Costa, L., Fernandes, R. J., Ribeiro, J., Figueiredo, P., Marinho, D. A., ... & Machado, L. (2010). Determination of the drag coefficient during the first and second gliding positions of the breaststroke underwater stroke. Journal of Applied Biomechanics, 26(3), 324–331. https://doi.org/10.1123/jab.26.3.324.

Vogel, S. (1994). Life in moving fluids. Princeton University Press, NJ, 81–155.

Zamparo, P., Gatta, G., Pendergast, D. & Capelli, C. (2009). Active and passive drag: the role of trunk incline. European Journal of Applied Physiology, 106(2), 195–205. https://doi.org/10.1007/s00421-009-1007-8.