Relationship between muscular strength and sprints with changes of direction.

Sprints with changes of direction (COD) have been traditionally associated with performance in team sports. Jumping tests have been used as predictors of COD; however, there are not too many studies analyzing how dominance affects the best performance of the turn. The purpose of this study was to explore the relationship between tests pertaining to jumps (1 and 2 legs) and COD (right and left turns). Forty-two male students were selected at the Faculty of Physical Education (age: 20.1 ± 3.7 years; weight: 73.4 ± 8.4 kg; body mass index: 23.1 ± 2.6 kg·m(-2); and fat mass: 17.1 ± 8.8%). All the subjects had right leg dominance. The COD tests were assessed using three 10-m sprint tests (90° right and left turns and 180° turn). Jumps were countermovement jumps (CMJs with 1 and 2 legs) and the drop jump (DJ). Pearson coefficient correlation and stepwise regression analyses were performed. Our results showed that both CMJs and DJs were associated with COD. The CMJ with the right leg had the best coefficient correlation with left COD time (r = -0.64; p < 0.01). Also, the CMJ was associated with COD180° time (r = -0.60; p < 0.01). After regression analysis, only right one-leg CMJ and CMJ were predictors of left COD time (adjusted R2 = 0.46; p < 0.01). The main finding of this study was that the CMJ, but not the DJ, was the best predictor of dominant side COD. Jumps are an important component of team sport training because they improve COD performance. However, coaches use several types of jumps during training; our results suggest that jumps similar to the CMJ should be useful tools to improve COD, which helps to specify better training prescription.

Relationship between age, category and experience with the soccer referee's self-efficacy.

Soccer referees (SRs) encounter stressful situations during competitions and sometimes even outside them, which may affect their decision making. Therefore, it is important that they possess or acquire optimal levels of self-efficacy, since it is related to less stress during competition, also guaranteeing sports performance and prevent sports abandonment. The objectives of this study were to characterize the profile, in terms of self-efficacy, of SRs depending on their category, age, and experience and to determine the relationship of these factors on SR self-efficacy. Two-hundred fifty-six Spanish referees participated in this study and Referee Self-Efficacy Scale was administered and completed. The results indicated that the SRs older than 25 years, of national category, and with experience greater than or equal to 8 years, have higher levels of self-efficacy than those with the least (p < .01). Likewise, moderate positive correlations were also observed between global self-efficacy and the category, age, and experience of the SRs. In conclusion, age, category and experience factors relate the self-efficacy of the SR, which can explain up to 17% of the variance, affecting decision-making and other decisive behaviors in the competition. These findings are of interest to delegations and referee committees seeking to implement psychological intervention programs to prevent burnout and abandonment of sports practice due to the consequences of low self-efficacy.