Are rowing peak and mean forces sex specific when using Big blades with Randall foils?

Leão, J1, Cardoso, R2, Rios, M3, Gomes, B4, Abraldes, JA5 Fernandes, RJ6
1Faculty of Sport, University of Porto, Porto, Portugal.
2Faculty of Sport, University of Porto, Porto, Portugal.
3Faculty of Sport, University of Porto, Porto, Portugal.
4Faculty of Sport Sciences and Physical Education, University of Coimbra, Portugal.
5Facultad de Ciencias del Deporte. Universidad de Murcia.
6Faculty of Sport, University of Porto, Porto, Portugal.

The propulsive phase of the rowing cycle is critical for boat speed and the blade size and shape plays an important role to enhance performance. To achieve its optimization, recently it was added a strip of plastic – the Randall foils – to the top edge of a rowing Big blade. Our aim was to investigate if there were differences on peak and mean force values produced by Big blades with and without Randall foils between sexes. Ten rowers (5 females) with 9 ± 6 years of training and competitive experience volunteered to participate in the current study. Their main anthropometric characteristics were: 24.2 ± 7.7 and 25.2 ± 7.1 years of age, 166.8 ± 8.8 cm and 185.0 ± 8.7 of height, 63.7 ± 7.5 and 77.8 ± 7.4 kg of body mass and 22.7 ± 1.2 and 22.6 ± 1.2 kg∙m-2 of body mass index for females and males (respectively). Rowers performed two bouts of 90 s tethered rowing in a 25 m indoor swimming pool with 24 h in between using Big-Blades with and without the foils. The force exerted was measured using a load-cell with a measurement capacity of 4.905 N and a recording rate of 200 Hz coupled to the stern of the boat by a 5 m steel cable. After a visual inspection, five consecutive rowing cycles from the central part of the bouts (from the 30-60 s interval) were analyzed using a MATLAB routine (MATLAB R2020a, The MathWorks Inc., Natick, MA, USA). Then the peak and mean force values were related with the rowers body weight. All tests were randomized and a paired samples t-test was used to compare the differences between variables in both conditions and sexes (p < 0.05). It was assessed the peak and mean forces (the mean of all peak forces of each rowing cycle and mean force value for female and male, respectively) relative to rowers body weight (Table1). It was observed that both female and male rowers produced similar peak force when using the Randall foils. Male rowers presented higher values of peak force variation, and female rowers of mean force variation, when using Big blades with Randal foils. The current data evidenced that females are able to take more advantage than males when using Big blades with Randall foils, which might allow them to maintain higher values of force during the propulsive phase of the rowing cycle. Since the rowing races have become highly competitive, the smallest difference can make an impact on the result. In the future we will aim to increase the small size and investigate in higher depth the impact that Randall foils for the both sexes.

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