Backstroke start performance: the impact of using the Omega OBL2 backstroke ledge

Abstract

FINA recently approved the backstroke ledge (Omega OBL2) to improve backstroke start performance in competition, but its performance has not been thoroughly evaluated. The purpose of this study was to compare the mechanics of starts performed with and without the OBL2. Ten high-level backstroke swimmers performed three starts with, and three starts without, the OBL2. A wall-mounted force plate measured the lower limb horizontal impulse, vertical impulse, take-off velocity and take-off angle. Entry distance, time to 10 m and start of hip and knee extension were recorded using video cameras. Starts performed with the OBL2 had a 0.13 s lower time to 10 m, 2.5% less variability in time to 10 m and 0.14 m greater head entry distance. The OBL2 provides a performance advantage by allowing an increased head entry distance rather than larger horizontal impulse on the wall. This may be due to the swimmers assuming different body positions during the start manoeuvre. Additional studies are needed to evaluate factors that contribute to improved performance when using the OBL2. Swimmers should train with the OBL2 and use it in competition to ensure optimal start performance.

Head Depth and Head Speed During Competitive Backstroke Ledge Starts

“…Our data reveals that the mean distance at water entry (Xentry) was 0.10 m (95% CI 0.07, 0.14 m) further from the wall with use of the ledge. This is consistent with the findings reported in the recent study by Barkwell and Dickey (2017). While we did not measure the actual forces generated by the swimmers during the start and therefore cannot state that this finding is specifically due to the introduction of the ledge, there does not appear to be any alternative explanatio n. Mean values for the starts performed with the backstroke ledge were 0.36 m·s -1 (95% CI 0.14, 0.56 m·s -1 ) faster (ResVelentry) and resulted in 3.47 (95% CI -0.70, 7.25) steeper angle of entry in comparison to starts performed without a ledge (Figure 4).…”

“…These assertions are intertwined with wholly unsupported insinuations of increased performance, claiming that a greater starting angle allows the swimmer's feet to make less contact with the water during the start and creates a longer jump trajectory (Gajanan, 2016). This seems to be, at least partially, substantiated by the recent study by Barkwell and Dickey (2017) describing starts executed with the ledge by "high-level backstroke swimmers." In contrast, novice swimmers have been shown to be less predictable and perhaps at greater risk in shallow water as compared to experienced elite swimmers (Cornett, Naganobori, & Stager, 2012).…”

“…Previous literature from our lab characterized variables pertaining to normal backstroke starts (head depth and speed, Cornett et al, 2011). Only a single report analyzing backstroke starts of "high-level swimmers" while using a 'ledge' was found (Barkwell & Dickey, 2017). The lack of information in this regard is an issue as USA Swimming has already approved the ledge for use by all swimmers in competition.…”

“…How often this occurs has not been reported. In order to prevent swimmers' feet from slipping during starts, a temporary ledge (79 cm x 8 cm x 2 cm at base with 10° slope; see Barkwell and Dickey, 2017) coated with an anti-slip surface was introduced into the commercial market in September 2014. The international governing body for swimming referred to as the Fédération Internationale de Natation (FINA) and USA Swimming, the United States' governing body for swimming, each approved the ledge for competition usage shortly thereafter.…”

Start and turn performances of elite sprinters at the 2016 European Championships in swimming

“…Overall, in the starting parameters, a significant stroke effect was observed, mostly between Backstroke and the remaining swimming strokes. These differences can be related to the specificity of the back start, that is the only where the swimmer starts in the water, reducing mostly the flight time, entry time and entry distance (Barkwell & Dickey, 2017;de Jesus et al, 2013).…”