ObjectiveThe unique foot morphology and distinctive functions facilitate complex tasks and strategies such as standing, walking, and running. In those weight-bearing activities, postural stability (PS) plays an important role. Correlations among foot type, PS, and other musculoskeletal problems that increase sport injury risk are known. However, long-term associations among the foot type, the PS, and body weight (BW) distribution are lacking. Thus, the purpose of this study was to longitudinally identify changes in foot morphology, PS, and symmetry in BW distribution during adolescence among elite male soccer players.MethodsThirty-five Czech elite male soccer players (age, 15.49 ± 0.61 years; BW, 64.11 ± 6.16 kg; body height, 174.62 ± 5.71 cm) underwent foot type, PS, and BW distribution measurements during 3 consecutive years (T1, T2, T3). The Chippaux-Smirak index (CSI), BW distribution, and centre of pressure (COP) displacement (total traveled way [TTW]) of each player for the preferred (PL) and non-preferred leg (NL) were acquired. Repeated-measures analysis of variance (RM ANOVA), Bonferroni´s post hoc tests, and partial eta-squared (ηp2) coefficient were used for investigating the effect of time on selected variables and effect size evaluation.ResultsStatistically significant effect of time on CSI values (PL: F2,68 = 5.08, p < 0.01, ηp2 = 0.13 and NL: F2,68 = 10.87, p < 0.01, ηp2 = 0.24) and COP displacement values (PL: F2,68 = 5.07, p <0.01, ηp2 = 0.13; NL: F2,68 = 3.53, p <0.05, ηp2 = 0.09) for both legs over 3-years period was identified. Furthermore, the Bonferroni´s post hoc analysis revealed a significant improvement of PS values in the PL (TTWT1 = 1617.11 ± 520.22 mm vs. TTWT2 = 1405.29 ± 462.76, p < 0.05; and between TTWT1 = 1617.11 ± 520.22 mm vs. TTWT3 = 1370.46 ± 373.94, p < 0.05). Only BW distribution parameter showed no significant differences, although slightly improved over time.ConclusionsWe observed changes in foot typology, PS, and BW distribution in young elite male soccer players during 3 consecutive years. Results demonstrated that changes in PS and body weight distribution under the high-load sport conditions during adolescence may improve with aging, except for foot morphology. Therefore, foot morphology should be carefully monitored to minimize sport injury risk in professional young soccer players during adolescence. Further research is necessary to determine more clear associations between these parameters, soccer-related injuries, and sport performances.

the advanced capabilities of accelerometers offer a more robust data set that coaches or athletes can use to assess more than just jump height (Crewther et al., 2011; McMaster, Gill, Cronin, & McGuigan, 2013). Previous research has determined the validity and reliability of vertical jump height (Casartelli, Müller, & Maffiuletti, 2010; Castagna et al., 2013) and estimated power output (Comstock et al., 2011) derived from accelerometers, and generally agree that accelerometers offer a valid and reliable method for measuring these variables. However, other variables such as power output and velocity measures are not as valid or reliable (Choukou, Laffaye, & Taiar, 2014). Although jump height and power output are commonly used as performance measures in athletes, some coaches may also be interested in the role of force production

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Purpose. the aim of the present study was to investigate the relationship between golf players' performance, impact factors, and ball flight results with individual clubs when performing a full swing. Methods. the study involved 9 amateur golfers who performed a full swing test with 4 different clubs (short, middle, long iron, and driver) and then played a tournament round of golf. the players' performance was assessed by handicap and by game statistics from the tournament. the ball flight results were based on the resulting carry distance and the resulting side deviation from the target line. the impact factors were the initial ball speed, the club head speed, the smash factor, the face angle, the club path, and the face to path. Relationships between the players' performance, impact factors, and ball flight results were investigated. Results. A significant relationship was found between the resulting ball flight distance and handicap for long iron (r = -0.85; p < 0.01) and driver (r = -0.9; p < 0.01). Conversely, the resulting ball flight side deviation from the target line correlated with handicap in short iron (r = 0.78; p = 0.02). Conclusions. ball flight distance of long iron and driver and ball flight side deviation of short iron are key attributes of performance. the results suggest that in order to improve long term performance, players should aim for maximal distance with drivers and long irons (high smash factor) and for maximal accuracy with short irons (low face angle).