Fábio Heitor Alves Okazaki

The Relative Age Effect among Female Brazilian Youth Volleyball Players.

In sports, the relative age effect (RAE) refers to performance disadvantages of children born late in the competition year compared to those with birthdays soon after the cutoff date. This effect is derived from age grouping, a strategy commonly used in youth sport programs. The purpose of age grouping is to decrease possible cognitive, physical, and emotional differences among sport participants. In spite of the efforts to equate playing conditions, youth athletes born early in the competitive age group are selected to be part of squads more often than late-born athletes, even within the same 1-year category. Most RAE studies have been conducted on professional male athletes, including hockey (Boucher & Mutimer, 1994), soccer (Helsen, Starkes, & Winckel, 1998), baseball (Grondin & Koren, 2000), and tennis (Edwards, 1994). Skewed distributions favoring athletes born early in the selection year were also found in youth sports. Several studies investigating soccer (Helsen et al., 1998; Helsen, Winckel, & Williams, 2005; Glamser & Vincent, 2004), hockey (Barnsley & Thompson, 1988), and basketball (Delorme & Raspaud, 2008) demonstrated a strong RAE among young male athletes. Not as many studies focused on female athletes. In fact, to our knowledge no studies have been conducted on adult female athletes and only a few on young female athletes. Among these studies, only one significant RAE was found (Delorme & Raspaud, 2008), in which youth basketball players ranging from 7 to 17 years of age participated. Although significant due to its large sample size (n = 107,101), differences in actual proportions of players born in different quarters of the year were small (Q1 = 26.1%, Q2 = 27.4%, Q3 = 24.6%, Q4 = 21.9%). In fact, the difference between the proportion of players born in the first and last 6 months of the year is probably not meaningful in applied settings. Nevertheless, it is the only indication in the literature of RAE among young female players. Helsen et al. (2005) did not find a significant RAE among female soccer players under the age of 18 years who were selected from national teams of 10 European countries. Although not statistically significant, a larger percentage of players were born early in the competition year. Approximately 31% were born in the first quarter compared to 17% in the last quarter, and 67% were born in the first 6 months of the competitive year. While 44 young female athletes took part in the experiment, it is possible a slightly larger sample size would have produced significant results. Vincent and Glamser (2006) also demonstrated a lack of an RAE for female athletes. Female soccer players, ages 17 and 18 years, participating in the youth U.S. Olympic program participated in this study. Their physical development and social expectations were strongly credited for the results. The authors stated that postpubescent girls generally have shorter legs and wider hips, a larger body mass index, and a more endomorphic body type; all of which are considered to be highly disadvantageous to perThe Relative Age Effect Among Female Brazilian Youth Volleyball Players

IMAGERY INTERVENTION IN OPEN AND CLOSED TENNIS MOTOR SKILL PERFORMANCE

To assess use of imagery intervention in performance of two tennis motor skills the quasi-experimental design included a pre- and posttest and a control group. The tennis service shot and service receiving skill were selected as representative of open and closed skills, respectively. 48 subjects, male tennis players, whose ages ranged from 16 to 18 yr. (M = 17.2), were divided into two groups: (1) Technical practice only which was used as control group and (2) Imagery group who received both imagery and technical practice. Analysis of covariance showed a significant main effect for the imagery intervention on the closed skill (p = .002). Findings suggest that imaging a positive outcome may be more powerful in improving performance of closed skill movements than of open skill movements.