Is starting with the feet out of the water faster in backstroke swimming?

Abstract

This study aimed to determine if starting with the feet above the water (FAW) in male backstroke swimming resulted in faster start times (15-m time) than when the feet were underwater (FUW). It was hypothesised that setting higher on the wall would generate increased horizontal force and velocity, resulting in quicker starts. Twelve high-level male backstrokers performed three trials of the FAW and FUW techniques. A biomechanical swimming testing system comprising one force plate (1,000 Hz), four lateral-view (100Hz), and five overhead (50Hz) video cameras captured the swimmers' performance. Data for each participant's fastest trial for each technique were collated, grouped, and statistically analysed. Analysis included Wilcoxon, Spearman Rho correlation, and regression analysis. Wilcoxon results revealed a significantly faster start time for the FAW technique (p < 0.01). Peak horizontal force was significantly smaller for FAW (p = 0.02), while take-off horizontal velocity was significantly greater (p = 0.01). Regression analysis indicated take-off horizontal velocity to be a good predictor of start time for both techniques, and the horizontal displacement of the centre of mass for the FAW start.

Are the new starting block facilities beneficial for backstroke start performance?

“…For that purpose, both variants were verbally described by the research team (complying with FINA rules, SW 6.1), as well as visually depicted by video recordings. Moreover, verbal instruction and feedback were given during familiarisation to ensure that the start variants were performed correctly (Nguyen et al, 2014). Participants were marked at joint centres with black waterproof tape (0.018 m) for tracking during digitising process.…”

“…The great acceptance of these variants independent of backstroke event could indicate few biomechanical differences between them. The use of the wedge in those start variants could increase the vertical CM displacement, take-off angle and flight distance, considered decisive for successful backstroke start performance (de Jesus et al, 2011;Nguyen et al, 2014;Takeda, Itoi, Takagi, & Tsubakimoto, 2014). In fact, the wedge obviates part of friction mechanism, allowing better feet wall contact and masking pure static friction effects, which lead to the need of vertical force component hybridisation including the vertical wall reaction force.…”

“…In those, authors have assessed start phase times, time to reach 5-15 m mark, hip or centre of mass (CM) horizontal and vertical position at auditory signal and at swimmers' hands or head water contact, hip or CM horizontal and vertical velocity at swimmers' hands-off, takeoff and hip or CM immersion, take-off and entry angles. Despite researchers having mentioned that many competitive backstrokers have altered their starting technique to place their feet entirely emerged (Nguyen et al, 2014), findings have revealed contradictory results regarding which starting variant should be the most recommended for improving performance Nguyen et al, 2014).…”

“…In 2009 and 2013, the Federation Internationale de Natation (FINA) had authorised facility rule changes that could allow swimmers to take the most out of each backstroke start phase. This fact, combined with the complexity to perform successful backstroke start technique comparing with those for ventral events Nguyen, Bradshaw, Pease, & Wilson, 2014), had led the scientific community to a growing concern about the backstroke start technique (de Jesus, de Jesus, Fernandes, Vilas-Boas, & Sanders, 2014a).…”

“…Recently, studies have been conducted to show the effects of positioning feet entirely immersed and emerged (FINA rules, SW 6.1) on backstroke start performance indicators, regardless handgrips configuration Nguyen et al, 2014). In those, authors have assessed start phase times, time to reach 5-15 m mark, hip or centre of mass (CM) horizontal and vertical position at auditory signal and at swimmers' hands or head water contact, hip or CM horizontal and vertical velocity at swimmers' hands-off, takeoff and hip or CM immersion, take-off and entry angles.…”