The force–time profile of elite front crawl swimmers

Abstract

In this study, we used recently developed technology to determine the force-time profile of elite swimmers, which enabled coaches to make informed decisions on technique modifications. Eight elite male swimmers with a FINA (Federation Internationale de Natation) rank of 900+ completed five passive (streamline tow) and five net force (arms and leg swimming) trials. Three 50-Hz cameras were used to video each trial and were synchronized to the kinetic data output from a force-platform, upon which a motorized towing device was mounted. Passive and net force trials were completed at the participant's maximal front crawl swimming velocity. For the constant tow velocity, the net force profile was presented as a force-time graph, and the limitation of a constant velocity assumption was acknowledged. This allowed minimum and maximum net forces and arm symmetry to be identified. At a mean velocity of 1.92+0.06 m s⁻¹, the mean passive drag for the swimmers was 80.3+4.0 N, and the mean net force was 262.4+33.4 N. The mean location in the stroke cycle for minimum and maximum net force production was at 45% (insweep phase) and 75% (upsweep phase) of the stroke, respectively. This force-time profile also identified any stroke asymmetry.

Quantification of upper limb kinetic asymmetries in front crawl swimming

“…However, the upper limbs alternating movements do not necessarily ensure symmetry, particularly regarding upper limb coordination (Seifert, Chollet, & Allard, 2005), hand speed (Keskinen, 1994), hand path (Aujouannet, Bonifazi, Hintzy, Vuillerme, & Rouard, 2006a) and propulsive forces (Formosa, Sayers, & Burkett, 2013;Formosa et al, 2011;Yeater, Martin, White, & Gilson, 1981). So, it is not clear if the reported asymmetries can alter the optimal function or simply are within the limits of normal variation.…”

“…In fact, when performing front crawl, swimmers intend to keep an uninterrupted application of force in water, leading to a lower intra-cycle velocity variation (Barbosa et al, 2010;Figueiredo, Seifert, Vilas-Boas, & Fernandes, 2012) and, consequently, to an optimal performance (Formosa, Mason, & Burkett, 2011). However, the upper limbs alternating movements do not necessarily ensure symmetry, particularly regarding upper limb coordination (Seifert, Chollet, & Allard, 2005), hand speed (Keskinen, 1994), hand path (Aujouannet, Bonifazi, Hintzy, Vuillerme, & Rouard, 2006a) and propulsive forces (Formosa, Sayers, & Burkett, 2013;Formosa et al, 2011;Yeater, Martin, White, & Gilson, 1981).…”

Hand force symmetry during breaststroke swimming

“…A ocorrência de assimetria de força tem sido demonstrada em análises do nado crawl 4,15,22 , e é geralmente atribuída à característica de alternância unilateral da braçada e à mecânica da respiração 14,22 . Entretanto, assimetrias substanciais entre os lados do corpo também são encontradas em nados bilaterais, como é o caso do peito e do borboleta, mesmo nos nadadores mais rápidos do mundo 13 .…”

“…Segundo Sanders et al 14 , para atingir um desempenho de alto nível, ambos os braços e ambas as pernas devem contribuir de maneira ótima para maximizar a propulsão e para diminuir o arrasto. Os estudos encontrados analisaram a assimetria propulsiva no nado crawl 5,11,15 . Marinho et al 7 , embora tenham investigado a relação entre a força propulsiva e o desempenho nos quatro nados competitivos, não analisaram a assimetria bilateral.…”

Comparison of Active Drag Using the MRT-Method and the MAD-System in Front Crawl Swimming

“…In MAD-system condition, however, stroke length of the swimmer is constant and the swimming velocity is affected only by the stroke frequency, which is not the case in reality [2,3]. On the other hand, the drag in various swimming styles can be assessed by other two methods [4,5]. However, they can only evaluate the drag during maximal effort trials.…”