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

Abstract

We aimed to analyse the handgrip positioning and the wedge effects on the backstroke start performance and technique. Ten swimmers completed randomly eight 15 m backstroke starts (four with hands on highest horizontal and four on vertical handgrip) performed with and without wedge. One surface and one underwater camera recorded kinematic data. Standardised mean difference (SMD) and 95% confidence intervals (CI) were used. Handgrip positioning did not affect kinematics with and without wedge use. Handgrips horizontally positioned and feet over wedge displayed greater knee angular velocity than without it (SMD = -0.82; 95% CI: -1.56, -0.08). Hands vertically positioned and feet over wedge presented greater take-off angle (SMD = -0.81; 95% CI: -1.55, -0.07), centre of mass (CM) vertical positioning at first water contact (SMD = -0.97; 95% CI: -1.87, -0.07) and CM vertical velocity at CM immersion (SMD = 1.03; 95% CI: 0.08, 1.98) when comparing without wedge use. Swimmers extended the hip previous to the knee and ankle joints, except for the variant with hands vertically positioned without wedge (SMD = 0.75; 95% CI: -0.03, 1.53). Swimmers should preserve biomechanical advantages achieved during flight with variant with hands vertically positioned and wedge throughout entry and underwater phase.

The Effects of Plyometric Warm-up on Lower Limb Muscle Activity and Time to 10m in the Backstroke Swimming Start

“…This is not consistent with a proximal-to-distal order of joint extension. It remains unclear whether proximal-to-distal joint sequencing is optimal for backstroke starts, as some studies have found it to be associated with a shorter start time [3,16], while others have not [2,4]. However, in support of our second The Effects of Plyometric Warm-up on Lower Limb Muscle Activity and Time to 10m in the Backstroke Swimming Start hypothesis, we observed that longer head entry distances were strongly correlated with shorter times to 10 m.…”

“…We observed differences in timing of hip and knee extensor activity between conditions. A proximal-to-distal recruitment of muscle activation and resulting order of joint extension benefits jumps [17,18] and backstroke starts [16]; however, it should be noted that this is not consistently observed [2,4]. In this study, peak gluteus maximus activity occurred before that of vastus lateralis in the control condition, but after the vastus lateralis in the plyometric warm-up condition based on a statistically significant p-value and a large effect size.…”

“…These improvements include the introduction of the backstroke ledge (also referred to as the "backstroke wedge" or "backstroke start device"; Omega OBL2, Swiss Timing, Coregmont, Switzerland) in 2014. The backstroke ledge has resulted in faster start times [2][3][4][5]; however, coaches and athletes continue to search for competitive advantages.…”

“…Similarly, a proximal to distal order of joint extension also results in greater squat jump performance in both live participants and computer models [17,18]. However, this proximal to distal order of joint extension has not been consistently observed in backstroke starts [2]. This may indicate that some swimmers have difficulty achieving a proximal to distal order of muscle activation.…”

Different Lower-Limb Setup Positions Do Not Consistently Change Backstroke Start Time to 10 m

“…In 2014, the backstroke ledge was approved by FINA (Fédération internationale de natation, or International Swimming Federation) for use in competition. The backstroke ledge alters the angle as well as the coefficient of friction between the feet and the starting surface [1], fundamentally changing backstroke start performances [2][3][4]. Accordingly, findings from previous studies where the backstroke ledge was not used may no longer be relevant.…”