AIM: To evaluate if static stretching influences peak and end-range functional hamstring-to-quadriceps(H/Q) strength ratios in elite women athletes. METHODS: Eleven healthy female athletes in an elite competitive leve...AIM: To evaluate if static stretching influences peak and end-range functional hamstring-to-quadriceps(H/Q) strength ratios in elite women athletes. METHODS: Eleven healthy female athletes in an elite competitive level participated to the study. All the participants fulfilled the static stretching or non-stretching(control) intervention protocol in a randomized design on different days. Two static unassisted stretching exercises, one in standing and one in sitting position, were used to stretch both the hamstring and quadriceps muscles during these protocols. The total time for the static stretching was 6 ± 1 min. The isokinetic peak torque measurements for the hamstring and quadriceps muscles in eccentric and concentric modes and the calculations for the functional H/Q strength ratios at angular velocities of 60°/s and 180°/s were made before(pre) and after(post) the control or stretching intervention. The strength measurements and functional strength ratio calculations were based during the entire- and end-range of knee extension.RESULTS: The pre-test scores for quadriceps and hamstring peak torque and end range values were not significantly different between the groups(P > 0.05). Subsequently, although the control group did notexhibit significant changes in quadriceps and hamstring muscle strength(P > 0.05), static stretching decreased eccentric and concentric quadriceps muscle strength at both the 60°/s and 180°/s test speeds(P < 0.01). Similarly, static stretching also decreased eccentric and concentric hamstring muscle strength at both the 60°/s and 180°/s test speeds(P < 0.01). On the other hand, when the functional H/Q strength ratios were taken into consideration, the pre-intervention values were not significant different between the groups both during the entire and end range of knee extension(P > 0.05). Furthermore, the functional H/Q strength ratios exhibited no significant alterations during the entire and end ranges of knee extension both in the static stretching or the control intervention(P > 0.05). CONCLUSION: According to our results, static stretching routine does not influence functional H/Q ratio. Athletes can confidently perform static stretching during their warm-up routines.展开更多
This research work was designed to explore the effect of different washing processes (enzyme wash, enzyme stone wash, enzyme stone wash with bleaching, heavy enzyme stone wash with bleaching) on various properties of ...This research work was designed to explore the effect of different washing processes (enzyme wash, enzyme stone wash, enzyme stone wash with bleaching, heavy enzyme stone wash with bleaching) on various properties of stretch denim fabric. Different properties like tensile strength, tear strength, dimensional stability to washing, color fastness to washing, color fastness to water, color fastness to perspiration, color fastness to light, color fastness to rubbing, changes in fabric weight were investigated in context with different washing processes for stretch denim fabric. All tests were carried out according to the ISO (International Organization for Standardization). Enzyme washed fabric illustrated better performance regarding tear strength, tensile strength and dimensional stability;but showed moderate performance in different color fastness properties. But the color fastness to rubbing of heavy enzyme stone wash was excellent. No significant change was observed regarding the grade of color change and color staining for color fastness to wash, color fastness to perspiration and color fastness to light with respect to different types of washing processes like enzyme wash, enzyme stone wash, enzyme stone wash with bleaching and heavy enzyme stone wash with bleaching. The grade for dry rubbing and wet rubbing was comparatively better for enzyme wash rather than other washing processes. The GSM (gram per square meter) of stretch denim fabric also increased accordingly after different kinds of washing process rather than untreated stretch denim fabric. The dimensional stability of stretch denim fabric also altered after going through different washing process. The highest shrinkage was occurred in weft direction for heavy enzyme stone wash with bleaching.展开更多
Comprehensive performances of polytetrafluoroethylene(PTFE) flat filaments used as suture materials in medical field can be affected significantly by morphological and mechanical characteristics.Due to low tensile str...Comprehensive performances of polytetrafluoroethylene(PTFE) flat filaments used as suture materials in medical field can be affected significantly by morphological and mechanical characteristics.Due to low tensile strength and non-uniform morphology,PTFE flat filaments cannot be applied widely as medical sutures.In order to solve flaws above,PTFE flat filaments with constant linear density,550 dtex,are manufactured and dependences of morphology,frictional features and mechanical behaviors on stretching ratio and temperature are also analyzed.The results indicate that PTFE flat filaments with high tensile strength(1 922.0 cN) and excellent apparent performance can be manufactured at optimal stretching ratio and temperature,18.0 and350 ℃,respectively.展开更多
文摘AIM: To evaluate if static stretching influences peak and end-range functional hamstring-to-quadriceps(H/Q) strength ratios in elite women athletes. METHODS: Eleven healthy female athletes in an elite competitive level participated to the study. All the participants fulfilled the static stretching or non-stretching(control) intervention protocol in a randomized design on different days. Two static unassisted stretching exercises, one in standing and one in sitting position, were used to stretch both the hamstring and quadriceps muscles during these protocols. The total time for the static stretching was 6 ± 1 min. The isokinetic peak torque measurements for the hamstring and quadriceps muscles in eccentric and concentric modes and the calculations for the functional H/Q strength ratios at angular velocities of 60°/s and 180°/s were made before(pre) and after(post) the control or stretching intervention. The strength measurements and functional strength ratio calculations were based during the entire- and end-range of knee extension.RESULTS: The pre-test scores for quadriceps and hamstring peak torque and end range values were not significantly different between the groups(P > 0.05). Subsequently, although the control group did notexhibit significant changes in quadriceps and hamstring muscle strength(P > 0.05), static stretching decreased eccentric and concentric quadriceps muscle strength at both the 60°/s and 180°/s test speeds(P < 0.01). Similarly, static stretching also decreased eccentric and concentric hamstring muscle strength at both the 60°/s and 180°/s test speeds(P < 0.01). On the other hand, when the functional H/Q strength ratios were taken into consideration, the pre-intervention values were not significant different between the groups both during the entire and end range of knee extension(P > 0.05). Furthermore, the functional H/Q strength ratios exhibited no significant alterations during the entire and end ranges of knee extension both in the static stretching or the control intervention(P > 0.05). CONCLUSION: According to our results, static stretching routine does not influence functional H/Q ratio. Athletes can confidently perform static stretching during their warm-up routines.
文摘This research work was designed to explore the effect of different washing processes (enzyme wash, enzyme stone wash, enzyme stone wash with bleaching, heavy enzyme stone wash with bleaching) on various properties of stretch denim fabric. Different properties like tensile strength, tear strength, dimensional stability to washing, color fastness to washing, color fastness to water, color fastness to perspiration, color fastness to light, color fastness to rubbing, changes in fabric weight were investigated in context with different washing processes for stretch denim fabric. All tests were carried out according to the ISO (International Organization for Standardization). Enzyme washed fabric illustrated better performance regarding tear strength, tensile strength and dimensional stability;but showed moderate performance in different color fastness properties. But the color fastness to rubbing of heavy enzyme stone wash was excellent. No significant change was observed regarding the grade of color change and color staining for color fastness to wash, color fastness to perspiration and color fastness to light with respect to different types of washing processes like enzyme wash, enzyme stone wash, enzyme stone wash with bleaching and heavy enzyme stone wash with bleaching. The grade for dry rubbing and wet rubbing was comparatively better for enzyme wash rather than other washing processes. The GSM (gram per square meter) of stretch denim fabric also increased accordingly after different kinds of washing process rather than untreated stretch denim fabric. The dimensional stability of stretch denim fabric also altered after going through different washing process. The highest shrinkage was occurred in weft direction for heavy enzyme stone wash with bleaching.
基金the Doctoral Fund of Ministry of Education of China(No.CUSF-DH-D-2015012)National Natural Science Foundation of China(No.51403033)Fundamental Research Funds for the Central Universities,China(No.2232014D3-15)
文摘Comprehensive performances of polytetrafluoroethylene(PTFE) flat filaments used as suture materials in medical field can be affected significantly by morphological and mechanical characteristics.Due to low tensile strength and non-uniform morphology,PTFE flat filaments cannot be applied widely as medical sutures.In order to solve flaws above,PTFE flat filaments with constant linear density,550 dtex,are manufactured and dependences of morphology,frictional features and mechanical behaviors on stretching ratio and temperature are also analyzed.The results indicate that PTFE flat filaments with high tensile strength(1 922.0 cN) and excellent apparent performance can be manufactured at optimal stretching ratio and temperature,18.0 and350 ℃,respectively.
