Periodized versus Non-periodized Stretch Training on Gymnasts Flexibility and Performance

Static stretching (SS) can increase joint range of motion (ROM), due to neural, morphological, and physio-psychological factors. Periodized training programs (PD) (e. g., strength, power) are adopted to induce greater adaptations while avoiding overtraining. However, the effectiveness of periodized stretch training adaptations are unknown. Therefore, the objective of this study was to compare the effects of periodized and non-periodized (NP) stretching programs on flexibility, hamstrings stiffness and muscle performance. Sixteen gymnasts were allocated to either periodized or non-periodized SS training and tested pre- and post-8 weeks for countermovement jump height, hip flexors, hip extensors and dorsiflexors ROM, hamstrings stiffness and hamstrings and quadriceps peak torque. Both stretch training groups significantly and similarly increased hip extensor (33.2%), hip flexor (25.2%), and dorsiflexor (23.8%) ROM, hamstrings peak torque (7.9%) and jump height (8.1%) from pre - to post- training. Both groups decreased hamstrings stiffness across the last ten angles (32.1%). PD elicited consistently large magnitude flexibility effect size changes compared to small and moderate magnitude changes for the non-periodized. Therefore, 8-week PD and NP SS programs can decrease young gymnasts’ muscle-tendon stiffness and increase muscle performance. However, effect sizes indicate that PD stretch training was more advantageous to increasing flexibility and improving performance.

Cash Hedging in a Supply Chain

We study hedging cash-flow risks in a supply chain where firms invest internal funds to improve production efficiencies. We offer a decomposition framework to capture the cost-reduction and flexibility effect of hedging. It allows us to understand how a firm’s hedging choice depends on its supply chain partner’s decision, and how such interaction is affected by supply chain characteristics such as market size, cash-flow volatility, and correlation. When firms’ cash flows are independent of each other, they are more likely to hedge with a larger market size. When cash flows are correlated, the impact of market size and volatility on firms’ hedging decisions presents multiple patterns, contingent on whether their risks amplify or offset each other. This paper was accepted by Gustavo Manso, finance.

Electronic structure and conformational flexibility of d-cycloserine

The conformational flexibility effect on the valence and core electronic structures of d-cycloserine.

Evaluation performance of multiple plasticizer systems on the physicomechanical, crystallinity and thermogravimetry of polyvinyl chloride

The flexibility of polyvinyl chloride (PVC) materials is crucial in the production of urine bags and urinary tubing. However, the combination and concentration of plasticizers offers a variation of the plasticizing efficiency to the PVC matrix. In this study, several types of plasticizers, namely dioctyl adipate (DOA), diisononyl phthalate (DINP), dioctyl terephthalate (DOTP) and epoxidized soybean oil (ESO) were added into the PVC matrix to enhance the flexibility of PVC compounds. Increasing the plasticizer loading level improved elongation at break of PVC compounds, whereas the tensile strength, hardness and specific gravity deteriorated. In addition, DOA added to PVC compounds exhibited the highest plasticizing effect with the highest elongation at break results at lower percentages of plasticizer (≤50%). This is due to the linear chain of the DOA plasticizer promoting the slippage effect of polymer chains during stretching and thus imparting a higher flexibility. In addition, a higher loading level of plasticizer in PVC compounds also produced a marginal increment on the crystallinity and thermal stability of PVC compounds. Overall, DINP/DOA added to PVC compounds exhibited the highest flexibility effect (elongation at break) at higher percentages, but lowered tensile strength and crystallinity.