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 perfor10 mance 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 15 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 20 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.