JUMPING PERFORMANCE OF YOUNG GIRLS IN TRACK AND FIELD

Abstract

INTRODUCTION: Jumping performance, as demonstrated by several types of vertical jumps performed on a force platform by individuals of different ages, varies in terms of biomechanical analysis of the force-time curve (Dowling et al., 1993, Harman et al., 1990). The purpose of the present study was to examine the factors related to the jumping performance of young girls involved in track and field running and jumping events. METHODS: Fourteen young girls, averaging in chronological age 12.53 + 1.24 yrs, body height 160.78 + 9.78 cm and body weight 48.00 + 8.17 kg, participated in the study. Their performances were measured on a force-platform (Kistler type 9281 B, Instrument Corp., Amherst, NY) and sampled at 250 Hz while performing a test consisting of a vertical jump with swinging the arms (With Arms Jump - WAJ) and another without swinging the arms (Countermovement Jump - CMJ). The following results were obtained by employing temporal and force analysis and using the specialized program Bio-Ware. RESULTS: The maximum height of the center of gravity in WAJ (30.25 + 4.07 cm) was higher than in CMJ (26.25 + 3.50 cm), (Table 1). Table 1. Mean values, standard deviations and coefficients of variation of the parameters of jumping performance in the two types of vertical jumps (WAJ and CMJ). In contrast, the relative force exhibited by the subjects was lower in WAJ (1.33 + 0.17) than in CMJ (1.48 + 0.18). Higher coefficients of variation were observed in the WAJ variables, indicating a higher variability in the way the vertical jump was performed. The duration of the take-off phase was 0.764 + 0.17 s, and the duration from minimum to maximum vertical force was 0.407 + 0.17 s, with the coefficient of variation being high (41.8%). Factor analysis showed that: (a) the duration of the take-off phase, as well as the relative force applied by the subjects, played important roles in WAJ jumping performance; (b) the duration of the flight phase, the maximum height of center of gravity, the vertical velocity, and the duration from minimum to maximum force played the prime roles in CMJ jumping performance. CONCLUSIONS: The sample of young girls participating in the study exhibited differences in the factors related to their jumping performances. The lack of coordination of movements was obvious especially in WAJ. These results from those observed in jumping performance studies performed with older individuals, suggesting that further research is required at this basic stage of athletic development. REFERENCES: Dowling, J., Vamos, L. (1993). Identification of Kinetic and Temporal Factors Related to Vertical Jump Performance. Journal of Applied Biomechanics 9, 95-110. Harman, E. A., Rosenstein, M. T., Frykman, P. N., Rosenstein, R. M. (1990). The Effects of Arms and Countermovement on Vertical Jumping. Medicine and Science in Sports and Exercise 22, 825-833.