This article has been retracted at the request of the authors on April 16, 2020. They performed an a posteriori analysis of the data and identified inconsistencies that changed their evaluation of the results. The authors apologize for the inconvenience.
Matheus Barbalho, Victor S. Coswig, James Steele, James P. Fisher, Jurgen Giessing and Paulo Gentil
Rodrigo Ramirez-Campillo, Cristian Alvarez, Felipe García-Pinillos, Paulo Gentil, Jason Moran, Lucas A. Pereira and Irineu Loturco
Purpose: To compare the effects of plyometric drop jump (DJ) training against those induced by regular soccer training and assess the transference effect coefficient (TEC) of DJs (“trained exercises”) performed from 20- (DJ20) and 40-cm (DJ40) height boxes with respect to different physical qualities (jumping, linear and change of direction speed, kicking, endurance, and maximal strength) in youth male soccer players. Methods: Participants were randomly divided into a control group (n = 20; age: 13.5 [1.9] y) and a DJ training group (n = 19; age: 13.2 [1.8] y), and trained for 7 weeks. A 2-way analysis of variance for repeated measures with the within-subject factor time (preintervention and postintervention) and between-subject factor group (intervention vs control) was performed. To calculate the TECs between the trained exercises (DJ20 and DJ40) and the physical tests, the ratio between the “result gains” (effect size [ES]) in the analyzed physical qualities and the result gains in the trained exercises were calculated. The TECs were only calculated for variables presenting an ES ≥ 0.2. Results: Significant improvements (ES = 0.21–0.46; P < .05) were observed in the DJ training group, except in linear sprint performance. The control group improved only the maximal strength (ES = 0.28; P < .05). Significant differences were observed in all variables (ES = 0.20–0.55; P < .05) in favor of the DJ training group, except for maximal strength (group × time interaction). Conclusions: A plyometric training scheme based on DJs was able to significantly improve the physical performance of youth male soccer players. Overall, greater TECs were observed for DJ40 (0.58–1.28) than DJ20 (0.55–1.21).
Paulo Gentil, Tulio Cesar de Lima Lins, Ricardo Moreno Lima, Breno Silva de Abreu, Dario Grattapaglia, Martim Bottaro, Ricardo Jacó de Oliveira and Rinaldo Wellerson Pereira
The current study investigated the association between vitamin-D-receptor (VDR) genotypes with bone-mineral density (BMD) and its interaction with physical activity level (PAL). Individuals in a sample of 192 volunteers (67.84 ± 5.23 years) underwent BMD evaluation and were genotyped for VDR ApaI, BsmI, FokI, and TaqI polymorphisms. Haplotypes were reconstructed through expectation-maximization algorithm, and regression-based haplotype-specific association tests were performed with studied phenotypes. None of the polymorphisms were associated with BMD at any site; however, haplotype was associated with femoral-neck and Ward’s-triangle BMD. Interaction between PAL and VDR genotypes was significant for the FokI polymorphism at femoral-neck and Ward’s-triangle BMD. The FokI T/T genotype was associated with higher BMD in active women. It was concluded that VDR haplotypes, but not genotypes, are associated with femoral-neck and Ward’s-triangle BMD in post-menopausal women. Moreover, the results suggest that VDR FokI polymorphism might be a potential determinant of BMD response to physical activity.