scholarly journals Effects of verbal knee alignment instructions on knee kinematics, kinetics and the performance of a single-leg jump in female adolescent soccer players

2019 ◽  
Vol 22 (2) ◽  
pp. 106-114
Author(s):  
Wilhelmus Johannes Andreas Grooten ◽  
Oskar Karlefur ◽  
David Conradsson
2020 ◽  
Vol 20 (1) ◽  
Author(s):  
Yuri V. Faustino-da-Silva ◽  
Diogo V. Martinho ◽  
Manuel J. Coelho-e-Silva ◽  
João Valente-dos-Santos ◽  
Jorge Conde ◽  
...  

Abstract Background Skeletal age (SA) is considered the best method of assessing biological maturation. The aim of this study was to determine intra-observer (reproducibility) and inter-observer agreement of SA values obtained via the Greulich-Pyle (GP) method. In addition, the variation in calculated SAs by alternative GP protocols was examined. Methods The sample was composed of 100 Portuguese female soccer players aged 12.0–16.7 years. SAs were determined using the GP method by two observers (OB1: experience < 100 exams using GP; OB2: experience > 2000 exams using several methods). The radiographs were examined using alternative GP protocols: (wholeGP) the plate was matched to the atlas as an overall approach; (30-boneGP) bone-by-bone inspections of 30-bones; (GPpmb) bone-by-bone inspections of the pre-mature bones only. For the 30-boneGP and GPpmb approaches, SA was calculated via the mean (M) and the median (Md). Results Reproducibility ranged 82–100% and 88–100% for OB1 and OB2, respectively. Inter-observer agreement (100 participants multiplied by 30 bones) was 92.1%. For specific bones, agreement rates less than 90% were found for scaphoid (81%), medial phalange V (83%), trapezium (84%) and metacarpal V (87%). Differences in wholeGP SAs obtained by the two observers were moderate (d-cohen was 0.79). Mean differences between observers when using bone-by bone SAs were trivial (30-boneGP: d-cohen less than 0.05; GPpmb: d-cohen less than 0.10). The impact of using the mean or the median was negligible, particularly when analyses did not include bones scored as mature. Conclusion The GP appeared to be a reasonably reproducible method to assess SA and inter-observer agreement was acceptable. There is evidence to support a recommendation of only scoring pre-mature bones during later adolescence. Further research is required to examine whether these findings are consistent in younger girls and in boys.


2011 ◽  
Vol 25 (1) ◽  
pp. 129-134 ◽  
Author(s):  
Mack D Rubley ◽  
Amaris C Haase ◽  
William R Holcomb ◽  
Tedd J Girouard ◽  
Richard D Tandy

2008 ◽  
Vol 41 ◽  
pp. S206
Author(s):  
Karine Boivin ◽  
Nicola Hagemeister ◽  
Katia Turcot ◽  
Michel Pelletier ◽  
Rachid Aissaoui ◽  
...  

Sports ◽  
2019 ◽  
Vol 7 (4) ◽  
pp. 80 ◽  
Author(s):  
Jaime González-García ◽  
Esther Morencos ◽  
Carlos Balsalobre-Fernández ◽  
Ángel Cuéllar-Rayo ◽  
Blanca Romero-Moraleda

Hip thrust (HT) is a loaded bridging exercise that requires more hip extension than a back squat (SQ) does, while in a back squat, triple flex extension occurs. Due to the specificity of each exercise, it is claimed that HT gains can be better transferred to actions where hip extension occurs. In addition, strength improvements during squatting can be transferred in a greater way to vertical plane movement, such as vertical jumping. However, its effects on the performance of female soccer players are unclear. For this reason, the purpose of this study was to analyze a 7-week training program on performance variables using either HT or SQ exercises in female adolescent soccer players without lifting experience (N = 24, age = 16.82 ± 1.56 years, height = 1.64 ± 0.55 cm, body mass = 58.35 ± 6.28 kg). Players were randomized into three groups: A back squat group (SQG; N = 8), hip thrust group (HTG; N = 8), and control group (CG; N = 8). Participants in the HTG and SQG joined a progressive resistance training program twice per week for 7 weeks with either HT or SQ exercises. A countermovement jump, 10–20 m sprint, T-test, and barbell velocity during HTs and SQs (with the load that represents ~60 and ~80% RM) were measured before and after the intervention. The HTG showed greater improvements in the 10-m sprint (d = 0.7), 20-m sprint (d = 0.46), T-test (d = 0.36), and barbell velocity at 80% repetition maximal (RM) (d = 0.53) and 60% RM (d = 1.02) during hip thrusts, while the SQG showed higher barbell velocity at 80% RM (d = −0.7) during back squats. These results may be useful for strength and conditioning coaches working with adolescent female soccer athletes, since both strengthening exercises improved performance in different ways due to the nature of the exercise.


2014 ◽  
Vol 24 (2) ◽  
pp. 134-141 ◽  
Author(s):  
Richard G. Celebrini ◽  
Janice J. Eng ◽  
William C. Miller ◽  
Christina L. Ekegren ◽  
James D. Johnston ◽  
...  

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