Futsal playing surface characteristics significantly affect perceived traction and change of direction performance among experienced futsal players.

We aimed to clarify the effect of different futsal playing surface structural properties on the resultant change of direction (COD) performance, perceived traction and frictional properties. Twenty experienced male university soccer players performed a COD slalom-course test and perceived traction evaluation on three different types of playing surfaces (area-elastic: AE, point-elastic no.1: PE1 and point-elastic no.2: PE2). Frictional properties of these surfaces were mechanically evaluated against a futsal shoe, using a hydraulic moving force platform, and expressed as available friction coefficient (AFC). In the COD performance test, the participants performed significantly better on the point-elastic surfaces (PE1 and PE2) when compared to the area-elastic surface (AE) (p < 0.05). Also, the PE2 surface was found to have the highest perceived traction (p < 0.001). The findings suggest that the relatively higher (4%) AFC explains the improvement in performance and traction perception on the PE2 surface. In this study, we successfully demonstrated that the structural difference (AE or PE) of futsal playing surface has a significant impact on the COD performance of experienced futsal players and their perceived level of traction (PE2) and the frictional properties.

Contribution of lower body segment rotations in various height soccer volley kicking.

We aimed to quantify the contribution of lower body segment rotations in producing foot velocity during the soccer volley kick. Fifteen male experienced university players kicked a soccer ball placed at four height conditions (0, 25, 50 and 75 cm). Their kicking motion was captured at 500 Hz. The effectiveness of lower body segment rotations in producing forward (Ffv) and upward (Fuv) foot velocity were computed and time integrated. Major contributors for Ffv were a) left hip linear velocity, b) knee extension and c) pelvis retroflexion (the pitch rotation). The contribution of a) become smaller as the ball height increased while those of b) and c) did not change significantly. Moreover, the pelvis clockwise rotation (the yaw rotation) showed apparent contribution only for volley kicking (except 0 cm height). Major contributors for Fuv were 1) knee flexion, 2) hip internal rotation, 3) pelvis clockwise rotation (the roll rotation) and 4) hip flexion. The contributions of 1) and 4) become consistently smaller as the ball height increased, while those of 2) and 3) become larger systematically. Soccer volley kicking was found to have unique adaptations of segmental contributions to achieve higher foot position while maintain foot forward velocity.

The Influence of Forefoot Bending Stiffness of Futsal Shoes on Multiple V-Cut Run Performance.

A forefoot bending stiffness (FBS) property of footwear is known to benefit athletes in running performance. To date, the efficacy of bending stiffness on performance is rather unknown from the perspective of futsal shoes. This study investigates the influence of bending stiffness property of three commercial futsal shoes on change of direction run resultant performance. Nineteen university level athletes participated in the human performance test (multiple V-cut change of direction run) on a hardwood flooring facility using three pairs of futsal shoes (i.e., S1, S2, and S3) with different models but similar in outsole material (S1-mass: 311 g, heel-to-toe drop: 10 mm, friction coefficient, 1.25; S2-mass: 232 g, heel-to-toe drop: 8 mm, friction coefficient: 1.34; and S3-mass: 276 g, heel-to-toe drop: 7 mm, friction coefficient: 1.30). The FBS properties for each shoe were mechanically measured. Results from the analysis of variance indicated that there was a significant difference of FBS value among the three shoes (S1: 0.32 Nm/deg., S2: 0.26 Nm/deg., and S3: 0.36 Nm/deg.) [F (2,8) = 28.50 (p < 0.001)]. Shoes with relatively higher shoe-playing surface friction coefficient (S2 and S3) had significant impact on the V-cut performance (p < 0.05) when compared with the shoe with lower friction coefficient (S1). In contrast to the literature, the shoe with the lowest FBS (S2) did not suffer any detriments on the resultant performance in the test conducted. These findings suggested that there could be other performance limiting factors, such as the friction coefficient, rather than FBS that have greater influence on the test outcomes.

Clarification of the Reactivity of 1,3,3,3-Tetrafluoropropene Oxides.

Our computation has successfully clarified the reluctant behavior of trans- and cis-1,3,3,3-tetrafluoropropene oxides 1c toward nucleophiles and led to the expectation that these epoxides would react under the Brønsted acid activation conditions. Actually, this was the case, and these epoxides smoothly opened with CF3SO3H, whose elimination after the protection of the resultant OH group afforded the enol benzoates as the enolate precursors, which nicely allowed us to construct the corresponding aldol products by reactions with various aldehydes.

Possible effects of diets on serum lipids, fatty acids and blood pressure levels in male and female Japanese university students.

OBJECTIVES: To prepare a dietary recommendation for young Japanese for the prevention of coronary heart disease, we surveyed the dietary habits, serum lipids, serum fatty acids and blood pressure levels among male and female students. METHODS: In this study, 175 male and 246 female university students were interviewed for the frequency of consumption of selected food items and the habit of skipping breakfast. Serum fatty acids were analyzed by gas chromatography. RESULTS: The frequencies of consumption of dishes cooked with oil and intake of vegetables were higher in female students than in male students. Serum n-6 polyunsaturated fatty acids were slightly higher in females students than in male students while that of serum n-3 polyunsaturated fatty acids was 6.4% in both sexes. For both males and females, those who skipped breakfast at least once a week were less likely to consume vegetables and fruits than those who did not. Female students who skipped breakfast were also less likely to consume fish and had lower composition of n-3 polyunsaturated fatty acid and higher systolic and diastolic blood pressure levels than males. For female, the intake of milk and dairy products correlated inversely with systolic blood pressure levels and the intake of n-3 polyunsaturated fatty acids correlated inversely with diastolic blood pressure levels. For males, the intake of fruits and consumption of dishes cooked with oil correlated inversely with systolic and diastolic blood pressure levels. CONCLUSION: Our findings suggest that increased intake of fish, milk and dairy products, fruits and vegetables from early adulthood and a regular dietary pattern are important to reduce the risk factors for coronary heart disease.