TY  - JOUR
A1  - Khajooei, Mina
A1  - Wochatz, Monique
A1  - Baritello, Omar
A1  - Mayer, Frank
T1  - Effects of shoes on children’s fundamental motor
skills performance
JF  - Footwear science : official journal of the Footwear Biomechanics Group
N2  - Progression or impediment of fundamental motor skills performance (FMSP) in children depends on internal and environmental factors. Shoes as an environmental constraint are believed to affect these movements as children showed to perform qualitatively better with sports shoes than flip-flop sandals. However, locomotor performance assessments based on biomechanical variables are limited. Therefore, the objective of this experiment was to assess the biomechanical effects of wearing shoes while performing fundamental motor skills in children. Barefoot and shod conditions were tested in healthy children between the age of 4 and 7 years. They were asked to perform basic and advanced motor skills including double-leg stance, horizontal jumps, walking as well as counter-movement jumps, single-leg stance and sprinting. Postural control and ground reaction data were measured with two embedded force plates. A 3D motion capture system was used to analyse the spatiotemporal parameters of walking and sprinting. Findings showed that the parameters of single- and double-leg stance, horizontal and counter-movement jump did not differ between barefoot and shod conditions. Most of the spatiotemporal variables including cadence, stride length, stride time, and contact time of walking and sprinting were statistically different between the barefoot and shod conditions. Consequently, tested shoes did not change performance and biomechanics of postural control and jumping tasks; however, the spatiotemporal gait parameters indicate changes in walking and sprinting characteristics with shoes in children.
KW  - Spatiotemporal
KW  - kinetics
KW  - jumping
KW  - stability
KW  - gait
Y1  - 2019
U6  - https://doi.org/10.1080/19424280.2019.1696895
SN  - 1942-4280
SN  - 1942-4299
VL  - 12
IS  - 1
SP  - 55
EP  - 62
PB  - Taylor & Francis
CY  - Abingdon
ER  - 
TY  - JOUR
A1  - Ramirez-Campillo, Rodrigo
A1  - Alvarez, Cristian
A1  - Garcia-Pinillos, Felipe
A1  - Sanchez-Sanchez, Javier
A1  - Yanci, Javier
A1  - Castillo, Daniel
A1  - Loturco, Irineu
A1  - Chaabene, Helmi
A1  - Moran, Jason
A1  - Izquierdo, Mikel
T1  - Optimal reactive strength index
BT  - is it an accurate variable to optimize plyometric training effects on measures of physical fitness in young soccer players?
JF  - Journal of strength and conditioning research : the research journal of the NSCA
N2  - Ramirez-Campillo, R, Alvarez, C, García-Pinillos, F, Sanchez-Sanchez, J, Yanci, J, Castillo, D, Loturco, I, Chaabene, H, Moran, J, and Izquierdo, M. Optimal reactive strength index: is it an accurate variable to optimize plyometric training effects on measures of physical fitness in young soccer players? J Strength Cond Res 32(4): 885–893, 2018—This study aimed to compare the effects of drop-jump training using a fixed drop-box height (i.e., 30-cm [FIXED]) vs. an optimal (OPT) drop-box height (i.e., 10-cm to 40-cm: generating an OPT reactive strength index [RSI]) in youth soccer players' physical fitness. Athletes were randomly allocated to a control group (n = 24; age = 13.7 years), a fixed drop-box height group (FIXED, n = 25; age = 13.9 years), or an OPT drop-box height group (OPT, n = 24; age = 13.1 years). Before and after 7 weeks of training, tests for the assessment of jumping (countermovement jump [CMJ], 5 multiple bounds), speed (20-m sprint time), change of direction ability (CODA [Illinois test]), strength {RSI and 5 maximal squat repetition test (5 repetition maximum [RM])}, endurance (2.4-km time trial), and kicking ability (maximal kicking distance) were undertaken. Analyses revealed main effects of time for all dependent variables (p < 0.001, d = 0.24–0.72), except for 20-m sprint time. Analyses also revealed group × time interactions for CMJ (p < 0.001, d = 0.51), depth jump (DJ) (p < 0.001, d = 0.30), 20-m sprint time (p < 0.001, d = 0.25), CODA (p < 0.001, d = 0.22), and 5RM (p < 0.01, d = 0.16). Post hoc analyses revealed increases for the FIXED group (CMJ: 7.4%, d = 0.36; DJ: 19.2%, d = 0.49; CODA: −3.1%, d = −0.21; 5RM: 10.5%, d = 0.32) and the OPT group (CMJ: 16.7%, d = 0.76; DJ: 36.1%, d = 0.79; CODA: −4.4%, d = −0.34; 5RM: 18.1%, d = 0.47). Post hoc analyses also revealed increases for the OPT group in 20-m sprint time (−3.7%, d = 0.27). Therefore, to maximize the effects of plyometric training, an OPT approach is recommended. However, using adequate fixed drop-box heights may provide a rational and practical alternative.
KW  - football
KW  - stretch-shortening cycle
KW  - maturity
KW  - training optimization
KW  - change of direction
KW  - jumping
Y1  - 2018
U6  - https://doi.org/10.1519/JSC.0000000000002467
SN  - 1064-8011
SN  - 1533-4287
VL  - 32
IS  - 4
SP  - 885
EP  - 893
PB  - Lippincott Williams & Wilkins
CY  - Philadelphia
ER  -