RESUMO
To determine the influence of midsole hardness on ground reaction force (GRF) features during badminton scissor jump takeoff and landing and the interactive effect of midsole hardness with playing and nonplaying limbs, data were collected from badminton athletes who performed scissor jumps while wearing shoes with two levels of midsole hardness. Temporal-spatial and GRF variables were calculated. Measurements of the soft and hard midsole conditions for playing versus non-playing sides were compared using two-way repeated measure analyses of variance. The playing and non-playing limbs showed different GRF features while performing scissor jump. During takeoff, no significant differences between the soft and hard midsole conditions were identified for the jump height in any of the GRF variables. During landing, the cushioning capacity might be affected by harder midsole indicated by higher vertical impact peak (p = 0.008). Meanwhile, the longer time-to-vertical impact peak (p = 0.007) and the lower loading rate of the vertical impact peak (p = 0.013) may be plausible indicators for cushioning. Current study indicated the playing-limb consistently showed dominance on both the propulsion and shock attenuation behaviours during scissor jump and that, for the footwear selection between 62C and 68C midsoles, expectation would be more on effects on landing characteristics than on propulsion performance.
RESUMO
This study is aimed at determining the effects of midsole thickness on movement characteristic during side cutting movement. Fifteen athletes performed side-step cutting while wearing shoes with varying midsole thicknesses. Temporal-spatial and ground reaction force variables as well as foot and ankle frontal kinematics were used to describe breaking and propulsive movement characteristics and modulation strategies. Regardless of midsole thickness, temporal-spatial variables and breaking and propulsive force during side cutting were statistically unchanged. Significantly greater peaks of ankle inversion and plantarflexion with a thicker sole and greater midtarsal pronation with a thinner sole were observed. Current results demonstrated that hypotheses formed solely based on material testing were insufficient to understand the adaptations in human movement because of the redundancy of the neuromusculoskeletal system. Participants were able to maintain temporal-spatial performance during side cutting while wearing shoes with midsoles of varying thicknesses. Increased pronation for a thinner sole might help reduce the force of impact but might be associated with an increased risk of excessive stress on soft tissue. Increased peak of ankle inversion and plantarflexion for a thicker sole may be unfavorable for the stability of ankle joint. Information provided in human movement testing is crucial for understanding factors associated with movement characteristics and injury and should be considered in the future development of shoe design.
RESUMO
Hydrogen (H2) production potential of water hyacinth (WH) and beverage wastewater (BW) mixture in powder and pellet form at various combination ratios were evaluated. Batch co-fermentation results showed peak biogas production of 105.5 mL and H2 production of 55.6 mL at the combination ratio of 1.6 g WH and 2.4 g BW in pellet form. With the same ratio in pellet form, the maximum H2 production rate 542 mL H2/L-d, maximum specific H2 production rate 869 mL H2/g VSS-d and H2 yield 13.65 mL/g feedstock were obtained, and were 88, 88 and 34% higher than its powder form. The predominant soluble metabolite was acetate in the concentration of 1059-2639 mg COD/L (40-79% of total metabolites) in most runs during co-fermentation of mixed feedstock. Carbon-to-nitrogen ratio and the physical form of the combined feedstock are essential criteria for optimum H2 production. Co-fermentation also alleviates the waste disposal problem of the industries.