RESUMEN
Introduction: Ballet demands diverse physical prowess, requiring dancers to execute movements symmetrically, irrespective of their dominant leg. Ballet often includes jumps, including the basic open-leg leap-the grand jeté-which requires uniform performance regardless of the leg on which the leap is initiated. However, no studies have simultaneously evaluated the effects of dominant leg or movement variation on jump height, leg split angle, jump time, and floor reaction forces during take-off and landing, which are related to the feeling of floating in the grand jeté. This study aimed to determine whether the high-level, stable, and beautiful performance required of professional ballet dancers in the grand jeté is affected by the dominant leg. Methods: Twelve female ballet dancers, all right leg dominant, performed the grand jeté 3 times on each side, distinguishing between dominant (right leg landing) and non-dominant (left leg landing) grand jetés. Utilising 3D movement analysis, we measured jump height, jump time, maximum leg split angle, and maximum vertical ground reaction force (VGRF) during take-off and landing. Mean values and coefficients of variation were calculated for each analysed parameter. Paired sample t-tests were conducted to assess differences between left and right grand jetés, with a significance level set at P < .05. Results: Statistically significant differences were observed in jump height (P = .028) and jump time (P = .001) when comparing the average of three trials for each side. However, no significant differences were found in maximum leg split angle (P = 0.643), maximum VGRF at take-off (P = .200), and maximum VGRF at landing (P = .109). In addition, no significant differences in coefficients of variation were identified for all items. Conclusion: Ballet dancers showed consistent performance on dominant and non-dominant legs but higher and longer jumps for grand jetés landing on the dominant leg, which may have affected overall performance.
RESUMEN
A countermovement jump (CMJ) is common in sport and often time-constrained. Little is known about contributors to quickness in jumps. This study examined effective predictors of time to take-off and effects of the starting position on reaction time and take-off time in a countermovement jump performed for quickness from upright and squat positions. Forty-nine collegiate athletes performed CMJs for quickness from upright and squatting starting positions to 75% of their maximal jump height. Several variables were calculated from the kinetic data related to jump performance. Correlation and multiple regression were used to determine variables related and predictive of time to take-off under both conditions. Paired t-tests evaluated differences in reaction and take-off times between conditions. In the upright condition, an increasing rate of force development and force, and decreasing time variables, impulses, and countermovement depth were associated with shorter time to take-off. The time to take-off prediction included rates of force development, force, time, and impulse. In the squat condition, shorter time to take-off was associated with lesser time variables, eccentric impulse, force at the end of the eccentric phase, and countermovement depth, and a greater rate of force development, concentric impulse, peak power, peak force, and reaction time. The time to take-off prediction equation included time to the bottom of the countermovement, time to peak force, and peak power. Reaction and take-off times were longer in the upright condition. Quick jump efficiency may be improved by strategies to increase maximum strength and the eccentric rate of force development while decreasing countermovement depth and time to bottom.