髋关节屈肌力矩与髋角关系属于肌肉收缩长度与力量关系的研究范畴。肌肉力量与肌肉长度的关系,最早是在动物实验中被证实的,后来在人体上获得证实。但到目前为止,我国运动解剖学和运动生物力学的教材与科研中,尚无一套系统完整的经过实...髋关节屈肌力矩与髋角关系属于肌肉收缩长度与力量关系的研究范畴。肌肉力量与肌肉长度的关系,最早是在动物实验中被证实的,后来在人体上获得证实。但到目前为止,我国运动解剖学和运动生物力学的教材与科研中,尚无一套系统完整的经过实验而得出的有关肌肉长度——力量关系的数据来具体说明肌肉初长度理论。国外Jensen et al[1]CL arkeet al[2),Elkihs et al[3],Williams and Stutzman[4]先后用不同方法对髋关节力量与髋角关系进行了研究。展开更多
Background:Hamstring muscle strain injury(hamstring injury) due to excessive muscle strain is one of the most common injuries in sports.The relationships among hamstring muscle optimal lengths and hamstring flexibilit...Background:Hamstring muscle strain injury(hamstring injury) due to excessive muscle strain is one of the most common injuries in sports.The relationships among hamstring muscle optimal lengths and hamstring flexibility and strength were unknown,which limited our understanding of risk factors for hamstring injury.This study was aimed at examining the relationships among hamstring muscle optimal length and flexibility and strength.Methods:Hamstring flexibility and isokinetic strength data and three-dimensional kinematic data for hamstring isokinetic tests were collected for11 male and 10 female recreational athletes.The maximal hamstring muscle forces,optimal lengths,and muscle lengths in standing were determined for each participant.Results:Hamstring muscle optimal lengths were significantly correlated to hamstring flexibility score and gender,but not to hamstring strength.The greater the flexibility score,the longer the hamstring muscle optimal length.With the same flexibility score,females tend to have shorter hamstring optimal muscle lengths compared to males.Hamstring flexibility score and hamstring strength were not correlated.Hamstring muscle optimal lengths were longer than but not significantly correlated to corresponding hamstring muscle lengths in standing.Conclusion:Hamstring flexibility may affect hamstring muscle maximum strain in movements.With similar hamstring flexibility,hamstring muscle maximal strain in a given movement may be different between genders.Hamstring muscle lengths in standing should not be used as an approximation of their optimal lengths in calculation of hamstring muscle strain in musculoskeletal system modeling.展开更多
μ-calpain activities and shear force values of bovine M. longissimus from Chinese Yellow crossbred bulls were analyzed,and the effect of delay chilling on μ-calpain activities and the tenderness of beef during postm...μ-calpain activities and shear force values of bovine M. longissimus from Chinese Yellow crossbred bulls were analyzed,and the effect of delay chilling on μ-calpain activities and the tenderness of beef during postmortem aging were studied. The results showed that delay chilling significantly improved μ-calpain activities (P<0.05) and enhanced the tenderness of bovine M. longissimus during earlier aging periods compared with conventional chilling. But in later aging periods,delay chilling weakened the effect on the tenderness of beef because of premature consumption of μ-calpain. The experiment results confirmed that delay chilling improved the rate of postmortem aging of beef and remarkably enhanced the tenderness of beef through the effect of delay chilling on μ-calpain activities.展开更多
Micro- injury （exercise-induced muscle damage, EIMD） will cause a temporary decline in muscle function, if not handled properly, it could cause more serious injury or overtraining, and even lead to the end of the at...Micro- injury （exercise-induced muscle damage, EIMD） will cause a temporary decline in muscle function, if not handled properly, it could cause more serious injury or overtraining, and even lead to the end of the athletes ＇ sports life. However, some studies have shown that an appropriate period of eccentric exercise training resulted in EIMD while promoted heart muscle fiber hypertrophy and corresponding muscle growth faster than exercise training, and there are the typical ＂ repetitive training effect＂ , ie after a period of the EIMD recovery, the muscle＇ s injury or delayed onset muscle soreness （DOMS） caused by the same movement is significantly reduced. So its deep study could help to guide the athlete to avoid or mitigate the negative effects which brought by EIMD, while could help to further clarify the process of the body to adapt to exercise training or mechanism.展开更多
A prominent example of seasonal phenotypic flexibility is the winter increase in thermogenic capacity （=summit metabolism, Msurn） in small birds, which is often accompanied by increases in pectoralis muscle mass and...A prominent example of seasonal phenotypic flexibility is the winter increase in thermogenic capacity （=summit metabolism, Msurn） in small birds, which is often accompanied by increases in pectoralis muscle mass and lipid catabolic capacity. Temperature or photoperiod may be drivers of the winter phenotype, but their relative impacts on muscle remodeling or lipid transport pathways are little known. We examined photoperiod and temperature effects on pectoralis muscle expres- sion of myostatin, a muscle growth inhibitor, and its tolloid-like protein activators （TLL-1 and TLL- 2）, and sarcolemmal and intracellular lipid transporters in dark-eyed juncos Junco hyemalis. We acclimated winter juncos to four temperature （3~C or 24~C） and photoperiod [short-day （SD） = 8L：16D; long-day （LD） = 16L：8D] treatments. We found that myostatin, TLL-I, TLL-2, and lipid transporter mRNA expression and myostatin protein expression did not differ among treatments, but treatments interacted to influence lipid transporter proteinexpression. Fatty acid translocase （FAT/CD36） levels were higher for cold SD than for other treatments. Membrane-bound fatty acid binding protein （FABPpm） levels, however, were higher for the cold LD treatment than for cold SD and warm LD treatments. Cytosolic fatty acid binding protein （FABPc） levels were higher on LD than on SD at 3℃, but higher on SD than on LD at 24℃. Cold temperature groups showed upregulation of these lipid transporters, which could contribute to elevated Msum compared to warm groups on the same photoperiod. However, interactions of temperature or photoperiod effects on muscle remodeling and lipid transport pathways suggest that these effects are context-dependent.展开更多
文摘髋关节屈肌力矩与髋角关系属于肌肉收缩长度与力量关系的研究范畴。肌肉力量与肌肉长度的关系,最早是在动物实验中被证实的,后来在人体上获得证实。但到目前为止,我国运动解剖学和运动生物力学的教材与科研中,尚无一套系统完整的经过实验而得出的有关肌肉长度——力量关系的数据来具体说明肌肉初长度理论。国外Jensen et al[1]CL arkeet al[2),Elkihs et al[3],Williams and Stutzman[4]先后用不同方法对髋关节力量与髋角关系进行了研究。
基金supported by the National Natural Science Foundation of China(No.81572212)the Fundamental Research Funds for the Central Universities of China(No.2016BS013)
文摘Background:Hamstring muscle strain injury(hamstring injury) due to excessive muscle strain is one of the most common injuries in sports.The relationships among hamstring muscle optimal lengths and hamstring flexibility and strength were unknown,which limited our understanding of risk factors for hamstring injury.This study was aimed at examining the relationships among hamstring muscle optimal length and flexibility and strength.Methods:Hamstring flexibility and isokinetic strength data and three-dimensional kinematic data for hamstring isokinetic tests were collected for11 male and 10 female recreational athletes.The maximal hamstring muscle forces,optimal lengths,and muscle lengths in standing were determined for each participant.Results:Hamstring muscle optimal lengths were significantly correlated to hamstring flexibility score and gender,but not to hamstring strength.The greater the flexibility score,the longer the hamstring muscle optimal length.With the same flexibility score,females tend to have shorter hamstring optimal muscle lengths compared to males.Hamstring flexibility score and hamstring strength were not correlated.Hamstring muscle optimal lengths were longer than but not significantly correlated to corresponding hamstring muscle lengths in standing.Conclusion:Hamstring flexibility may affect hamstring muscle maximum strain in movements.With similar hamstring flexibility,hamstring muscle maximal strain in a given movement may be different between genders.Hamstring muscle lengths in standing should not be used as an approximation of their optimal lengths in calculation of hamstring muscle strain in musculoskeletal system modeling.
基金Supported by the National High Technology Research and Development Program of China(2006BAD05A03)~~
文摘μ-calpain activities and shear force values of bovine M. longissimus from Chinese Yellow crossbred bulls were analyzed,and the effect of delay chilling on μ-calpain activities and the tenderness of beef during postmortem aging were studied. The results showed that delay chilling significantly improved μ-calpain activities (P<0.05) and enhanced the tenderness of bovine M. longissimus during earlier aging periods compared with conventional chilling. But in later aging periods,delay chilling weakened the effect on the tenderness of beef because of premature consumption of μ-calpain. The experiment results confirmed that delay chilling improved the rate of postmortem aging of beef and remarkably enhanced the tenderness of beef through the effect of delay chilling on μ-calpain activities.
文摘Micro- injury （exercise-induced muscle damage, EIMD） will cause a temporary decline in muscle function, if not handled properly, it could cause more serious injury or overtraining, and even lead to the end of the athletes ＇ sports life. However, some studies have shown that an appropriate period of eccentric exercise training resulted in EIMD while promoted heart muscle fiber hypertrophy and corresponding muscle growth faster than exercise training, and there are the typical ＂ repetitive training effect＂ , ie after a period of the EIMD recovery, the muscle＇ s injury or delayed onset muscle soreness （DOMS） caused by the same movement is significantly reduced. So its deep study could help to guide the athlete to avoid or mitigate the negative effects which brought by EIMD, while could help to further clarify the process of the body to adapt to exercise training or mechanism.
文摘A prominent example of seasonal phenotypic flexibility is the winter increase in thermogenic capacity （=summit metabolism, Msurn） in small birds, which is often accompanied by increases in pectoralis muscle mass and lipid catabolic capacity. Temperature or photoperiod may be drivers of the winter phenotype, but their relative impacts on muscle remodeling or lipid transport pathways are little known. We examined photoperiod and temperature effects on pectoralis muscle expres- sion of myostatin, a muscle growth inhibitor, and its tolloid-like protein activators （TLL-1 and TLL- 2）, and sarcolemmal and intracellular lipid transporters in dark-eyed juncos Junco hyemalis. We acclimated winter juncos to four temperature （3~C or 24~C） and photoperiod [short-day （SD） = 8L：16D; long-day （LD） = 16L：8D] treatments. We found that myostatin, TLL-I, TLL-2, and lipid transporter mRNA expression and myostatin protein expression did not differ among treatments, but treatments interacted to influence lipid transporter proteinexpression. Fatty acid translocase （FAT/CD36） levels were higher for cold SD than for other treatments. Membrane-bound fatty acid binding protein （FABPpm） levels, however, were higher for the cold LD treatment than for cold SD and warm LD treatments. Cytosolic fatty acid binding protein （FABPc） levels were higher on LD than on SD at 3℃, but higher on SD than on LD at 24℃. Cold temperature groups showed upregulation of these lipid transporters, which could contribute to elevated Msum compared to warm groups on the same photoperiod. However, interactions of temperature or photoperiod effects on muscle remodeling and lipid transport pathways suggest that these effects are context-dependent.
