Laser-induced breakdown spectroscopy （LIBS） has attracted many academic and industrial interests world-wide due to its unique advantages, such as little or no sample preparation requirement, in-situ/online and multi...Laser-induced breakdown spectroscopy （LIBS） has attracted many academic and industrial interests world-wide due to its unique advantages, such as little or no sample preparation requirement, in-situ/online and multi-elemental analysis, and remote sensing etc., and it has been regarded as a ＂future super star＂ for chemical analysis for many years . In China,展开更多
The developmental status of productivity in Chinese rural area is introduced. Since the implementation of the agriculture supporting policies in 2004, the productive forces in rural areas have been improved greatly. I...The developmental status of productivity in Chinese rural area is introduced. Since the implementation of the agriculture supporting policies in 2004, the productive forces in rural areas have been improved greatly. It is reflected on the following aspects: great enhancement of rural labors' cultural quality; the quantity of agricultural machines has been increased; the level of production management and decision has been increased greatly. The paper analyzes the promotion role played by the development of productive forces to rural residents' consumption conception. The development of productive forces has laid a solid foundation for changing rural residents' consumption concept; changed rural residents' consumption structure and improved the socialized degree of rural residents' consumption. Countermeasures on cultivating new consumption fields in rural areas are put forward including leading rural residents to foster the modern consumption conception; intensifying the governmental support and leading rural residents to set up healthy consumption concept.展开更多
There is an intrinsic traction force in the technological development which has various manifestations. It is from nonlinear interaction that occurs among the essential elements of technology and among the relevant te...There is an intrinsic traction force in the technological development which has various manifestations. It is from nonlinear interaction that occurs among the essential elements of technology and among the relevant technology. It is not the only decisive factor but to interweave with other tensions in the development of technology.展开更多
The paper aims to defme the lawfulness （model）, by which one can reliably estimate the distribution of motor units＇ force from the moment when leg extensor muscles start to generate the force until the moment when ...The paper aims to defme the lawfulness （model）, by which one can reliably estimate the distribution of motor units＇ force from the moment when leg extensor muscles start to generate the force until the moment when the maximal level is achieved. The study included 110 participants. To assess the contractile characteristics of leg extensors, standardized equipment and standardized isometric test in sitting position with the angle of the knee joint of 125° were used. The participants were instructed to exert their maximal force as quickly as possible. Using descriptive statistics, cluster analysis and fitting the exponential model of the distribution of force of leg extensor motor units in the whole range of force generation is defined. The model has the following form： y = 0.2051e3.3855x, where y is the motor units force expressed in daN （decanewtons）, x is the time expressed in s （seconds）. It provides an understanding of the control of multivariate motor unit recruitment and distribution of their force during sports movements as well as training programming for the adoption of forms for conlrolling force distribution of motor units, the development of their maximum force and their involvement speed.展开更多
Based on the two-energy equation model, taking into account viscous dissipation due to the interaction between solid skeleton and pore fluid flow, temperature expressions of the solid skeleton and pore fluid flow are ...Based on the two-energy equation model, taking into account viscous dissipation due to the interaction between solid skeleton and pore fluid flow, temperature expressions of the solid skeleton and pore fluid flow are obtained analytically for the thermally developing forced convection in a saturated porous medium parallel plate channel, with walls being at constant temperature. It is proved that the temperatures of the two phases for the local thermal nonequilibrium approach to the temperature derived from the one-energy equation model for the local thermal equilibrium when the heat exchange coefficient goes to infinite. The temperature profiles are shown in figures for different dimensionless parameters and the effects of the parameters on the local thermal nonequilibrium are revealed by parameter study.展开更多
At first, this article gives the calculating formulas about the mutual-motive mechanism of the economy development and its resource, environmental influence. And then it gives out relevant ideas about the sustainable ...At first, this article gives the calculating formulas about the mutual-motive mechanism of the economy development and its resource, environmental influence. And then it gives out relevant ideas about the sustainable development＇s realizing means, motive force and economic model.展开更多
Increased neck strength has been linked to a potential decrease in traumatic brain injuries(TBI).The purpose was to determine the efficacy of a neck-strengthening protocol using a novel neck-strengthening device to in...Increased neck strength has been linked to a potential decrease in traumatic brain injuries(TBI).The purpose was to determine the efficacy of a neck-strengthening protocol using a novel neck-strengthening device to increase isometric neck strength and rate of force development(RFD).Utilizing self-generated centripetal force,participants trained for 14 weeks.A linear mixed model was used to analyze the relationship between post-assessment measurements and pre-assessments measurements,while accounting for repeated measure random effect at the individual level,and a regular random error term.RFD values were 4.344 times higher in the clockwise direction and 5.978 times higher in the counterclockwise direction when comparing pre and post assessment measurements.Isometric neck strength increased significantly(p<0.05)in the cervical extension(p=0.010)and left lateral flexion(p=0.009)directions.The results can be used in strength training and clinical settings to potentially reduce the incidence of TBI.展开更多
The NCEP/NCAR R1 reanalysis data are employed to investigate the impact of forced and inertial instability in the lower troposphere over the Arabian Sea on the onset process of Indian summer monsoon(ISM),and to reveal...The NCEP/NCAR R1 reanalysis data are employed to investigate the impact of forced and inertial instability in the lower troposphere over the Arabian Sea on the onset process of Indian summer monsoon(ISM),and to reveal the important role of zonal advection of zonal geostrophic momentum played in the forced unstable convection.Results show that during the ISM onset the zero absolute vorticity contour(??=0)shifts northward due to the strong cross-equatorial pressure gradient in the lower troposphere over southern Arabian Sea.Thus a region with negative absolute vorticity is generated near the equator in the northern hemisphere,manifesting the evident free inertial instability.When a southerly passes through this region,under the influence of friction a lower convergence that facilitates the convection flourishing at the lower latitudes appears to the north of zero absolute vorticity contour.However,owing to such a traditional inertial instability,the convection is confined near the equator which does not have direct influence on the ISM onset.On the contrary in the region to the north of the zero absolute vorticity contour and to the south of the low pressure center near the surface,although the atmosphere there is inertially stable,the lower westerly jet can develop and bring on the apparent zonal advection of zonal geostrophic momentum.Both theoretical study and diagnosing analysis present that such a zonal advection of geostrophic momentum is closely associated with the zonal asymmetric distribution of meridional land-sea thermal contrast,which induces a convergence center near and further north of the westerly jet in the lower troposphere over the southwestern coast of the Indian Peninsula,providing a favorable lower circulation for the ISM onset.It illustrates that the development of convection over the Arabian Sea in late spring and early summer is not only due to the frictional inertial instability but also strongly affected by the zonal asymmetric distribution of land-sea thermal contrast.Moreover,before the ISM onset due to the eastward development of the South Asian High(SAH)in the upper troposphere,high potential vorticity is transported to the region over the Arabian Sea.Then a local trumpet-shaped stream field is generated to cause the evident upper divergence-pumping effect which favors the ISM onset.When the upper divergence is vertically coupled with the lower convergence resulted from the aforementioned forced unstable convection development near the southwestern coast of Indian Peninsula,the atmospheric baroclinic unstable development is stimulated and the ISM onset is triggered.展开更多
Purpose： The present study aimed to examine the effect of static stretching （SS） and a sport-specific dynamic stretching （DS） session at two specific post-stretch time intervals in highly trained female athletes ...Purpose： The present study aimed to examine the effect of static stretching （SS） and a sport-specific dynamic stretching （DS） session at two specific post-stretch time intervals in highly trained female athletes （age 19.90 ± 1.60 years; height 1.80 ±0.06 m; mass 76.87 ± 9.95 kg） on kinetic parameters of peak force, time-to-takeoff, and rate of force development. Methods： The data were collected over 3 days （randomized within subject design with control session）. Following each stretch session （SS vs. DS vs. control） of equal duration （7 min total： 30 s per targeted muscle group） participants performed countermovement jumping on a force platform at 1 and 15 rain after stretching. Results： The DS session significantly improved upon kinetic variables of rate of force development, peak force, and time-to-takeoffrelative to SS at 1 min after stretching. No significant effect was found at 15 min. Conclusion： Together these findings suggest that when training and competing to jump quickly and maximally the female athlete should incorporate DS instead of SS as part of their pre-competition warm-up, but conduct performance within 15 min of their warm-up to elicit maximal gains展开更多
Purpose： Long-term training specificity is thought to alter performance in tests evaluating strength and power production capability. The aim of the present study was to provide additional information to the limited ...Purpose： Long-term training specificity is thought to alter performance in tests evaluating strength and power production capability. The aim of the present study was to provide additional information to the limited existing knowledge concerning the possible differences of the force/time profile of squat jumping among different groups of young female athletes. Methods： One hundred and seventy-three adult women （20.1 ± 2.8 years, 1.71 ± 0.09 m, 65.6 ± 10.3 kg, mean± SD for age, height, and mass, respectively） engaged in track and field （TF）, volleyball （VO）, handball （HA）, basketball （BA）, and physical education students （PE） executed maximal squat jumps （SQJ） on a force plate. Pearson＇s correlation was used to identify the relationship between SQJ performance, the anthropometric characteristics and the biomechanical parameters. Differences concerning the biomechanical parameters among groups were investigated with analysis of variance, while the force- （FPD） or time- （TPD） dependency of SQJ execution was examined using principal components analysis （PCA）. Results： SQJ was unrelated to body height but significantly correlated with body mass （r = -0.26, p = 0.001）. TF jumped higher and produced larger peak body power output compared to all the other groups （p 〈 0.05）. All athletes were superior to PE since they performed the SQJ with a longer （p 〈 0.05） vertical body center of mass trajectory during the propulsion phase. PCA results revealed that TF significantly differentiated than the other groups by relying on FPD. Conclusion： Various different profiles of FPD and TPD were detected due to different sporting background in young female athletes. Since TF superiority in SQJ was relied on the larger power production and a greater FPD, female indoor team sport athletes are suggested to execute jumping exercises adopting the jumping strategies utilized by TE展开更多
The authors of the original research entitled“Acute Effects of a Fatiguing Protocol on Peak Force and Rate of Force Development of the Hamstring Muscles in Soccer Players”[2]thank the authors for diligently examinin...The authors of the original research entitled“Acute Effects of a Fatiguing Protocol on Peak Force and Rate of Force Development of the Hamstring Muscles in Soccer Players”[2]thank the authors for diligently examining our manuscript and raising some key points in their letter to the Editor.展开更多
Although the ability to produce force rapidly is an indispensable characteristic of optimal health and performance, screening for this very critical parameter of strength is difficult because of clinician time constra...Although the ability to produce force rapidly is an indispensable characteristic of optimal health and performance, screening for this very critical parameter of strength is difficult because of clinician time constraints. The purpose this study was to investigate relationships between peak torque （PT） and rate of torque development （RTD） at 0-30, 0-50, 0-100, and 0-200 ms in female collegiate soccer athletes. Seventeen female collegiate soccer athletes were recruited. Isometric PT and RTD were collected at the hip abductors （AB）, hip adductors （AD）, knee extensors （KE） and knee flexors （KF）. The coefficients of determination were calculated to evaluate the association between PT and RTD. Normalized AB, AD and KF PT were significantly correlated to RTD at 0-30, 0-50, 0-100 and 0-200 ms, while KEPT was only significantly correlated to RTD at 0-100 and 0-200 ms. The results of this study indicate that PT is a viable, indirect indicator of early late phase RTD at separate time intervals at the AB, AD and KF. However, it is likely that other physiological factors coupled with PT are required to provide information on the rapid force production capabilities of the KFs and KEs based on the percent of common variance observed.展开更多
We compared the effects of low intensity concentric(CON)and eccentric(ECC)exercise on the force and neural responses of the dominant(exercised)elbow flexors(EFs),and studied if these conditions could induce cross-over...We compared the effects of low intensity concentric(CON)and eccentric(ECC)exercise on the force and neural responses of the dominant(exercised)elbow flexors(EFs),and studied if these conditions could induce cross-over effects to the contralateral(non-exercised)EFs.Fifteen subjects(8 males)completed all conditions(CON and ECC:6 sets of low intensity exercise to failure;control:rest)in separate visits with a randomized order.Maximal isometric force and electromyography(EMG)of the dominant and contralateral EFs were assessed at pre,immediate-,24-,and 48-h-post.Two-factor(condition and time)linear mixed-model analyses were performed to examine the force and EMG responses.Immediately post CON,contralateral EFs force was significantly(p=0.026)higher(12.41%)than control,but no cross-over effects regarding the neural responses were observed.Immediately post ECC,dominant EFs force was significantly lower in ECC,compared to CON(p=0.003)and control(p<0.001).This force remained depressed at 24-and 48-h post ECC,when compared to CON(p<0.001)and control(p<0.001).Our data suggests that submaximal unilateral exercises are not likely to impair contralateral muscle strength performance.Instead,concentric exercises may acutely improve muscle strength for the contralateral limb.However,this effect is not explained by changes in muscle excitation.展开更多
Rate of force development(RFD)and impulse(IMP)are important mechanical measures of muscular performance but are relatively unused within the rehabilitation and performance community.Due principally to access to low-co...Rate of force development(RFD)and impulse(IMP)are important mechanical measures of muscular performance but are relatively unused within the rehabilitation and performance community.Due principally to access to low-cost testing devices and understanding the utility of these measures.The aim of this study therefore was to quantify the reliability of various force-time variables using load-cell technology collected via isometric knee extension whilst constrained in an isokinetic device(CON90)or unconstrained on a physiotherapy plinth at 60 and 90 degree angles(UNCON60 and UNCON90).Thirty-two volunteers had their peak force(PF),RFD,peak RFD(PRFD),and IMP assessed across three protocols.For all variables,UNCON60 had the largest variability across all measures.PF and PRFD were found to have small variability(ICC>0.67 and CV<10%).With regards to RFD 2080 all three protocols were found to have moderate variability all ICCs above 0.75,however,all CVs were greater than 10%ranging from~11%-22%.Finally,IMP 2080 was found to have moderate variability for both CON90 and UNCON90,the absolute consistency once more greater than 10%(~11%-25%).Using the constrained and unconstrained protocols,PF and PRFD can be measured reliably between trials with 90 degree knee position.展开更多
Science and technology are foremost productive forces,while industry is the cornerstone of the national economy.The pursuit of integrated advancement in technological and industrial innovation is,therefore,critical to...Science and technology are foremost productive forces,while industry is the cornerstone of the national economy.The pursuit of integrated advancement in technological and industrial innovation is,therefore,critical to the development of new quality productive forces and the entire Chinese modernization agenda.展开更多
In developing society＇s productive forces, the construction of an ecological civilization must conform to nature, stress civilized development, protect natural ecosystems, pursue social reproduction in accordance wit...In developing society＇s productive forces, the construction of an ecological civilization must conform to nature, stress civilized development, protect natural ecosystems, pursue social reproduction in accordance with the rules of ecological economy, gradually change the traditional high-carbon and linear mode of production of large-scale machine industry into a low-carbon and circular mode of production, and satisfy the demands of a virtuous cycle of man-made ecosystems through scientific development.展开更多
文摘Laser-induced breakdown spectroscopy （LIBS） has attracted many academic and industrial interests world-wide due to its unique advantages, such as little or no sample preparation requirement, in-situ/online and multi-elemental analysis, and remote sensing etc., and it has been regarded as a ＂future super star＂ for chemical analysis for many years . In China,
基金Supported by Judge Committee of Philosophy and Science Research Results of Hunan Province (1011254B)
文摘The developmental status of productivity in Chinese rural area is introduced. Since the implementation of the agriculture supporting policies in 2004, the productive forces in rural areas have been improved greatly. It is reflected on the following aspects: great enhancement of rural labors' cultural quality; the quantity of agricultural machines has been increased; the level of production management and decision has been increased greatly. The paper analyzes the promotion role played by the development of productive forces to rural residents' consumption conception. The development of productive forces has laid a solid foundation for changing rural residents' consumption concept; changed rural residents' consumption structure and improved the socialized degree of rural residents' consumption. Countermeasures on cultivating new consumption fields in rural areas are put forward including leading rural residents to foster the modern consumption conception; intensifying the governmental support and leading rural residents to set up healthy consumption concept.
文摘There is an intrinsic traction force in the technological development which has various manifestations. It is from nonlinear interaction that occurs among the essential elements of technology and among the relevant technology. It is not the only decisive factor but to interweave with other tensions in the development of technology.
文摘The paper aims to defme the lawfulness （model）, by which one can reliably estimate the distribution of motor units＇ force from the moment when leg extensor muscles start to generate the force until the moment when the maximal level is achieved. The study included 110 participants. To assess the contractile characteristics of leg extensors, standardized equipment and standardized isometric test in sitting position with the angle of the knee joint of 125° were used. The participants were instructed to exert their maximal force as quickly as possible. Using descriptive statistics, cluster analysis and fitting the exponential model of the distribution of force of leg extensor motor units in the whole range of force generation is defined. The model has the following form： y = 0.2051e3.3855x, where y is the motor units force expressed in daN （decanewtons）, x is the time expressed in s （seconds）. It provides an understanding of the control of multivariate motor unit recruitment and distribution of their force during sports movements as well as training programming for the adoption of forms for conlrolling force distribution of motor units, the development of their maximum force and their involvement speed.
基金Project supported by the National Natural Science Foundation of China (No. 10272070) and the Shanghai Leading Academic Discipline Project (No.Y0103)
文摘Based on the two-energy equation model, taking into account viscous dissipation due to the interaction between solid skeleton and pore fluid flow, temperature expressions of the solid skeleton and pore fluid flow are obtained analytically for the thermally developing forced convection in a saturated porous medium parallel plate channel, with walls being at constant temperature. It is proved that the temperatures of the two phases for the local thermal nonequilibrium approach to the temperature derived from the one-energy equation model for the local thermal equilibrium when the heat exchange coefficient goes to infinite. The temperature profiles are shown in figures for different dimensionless parameters and the effects of the parameters on the local thermal nonequilibrium are revealed by parameter study.
文摘At first, this article gives the calculating formulas about the mutual-motive mechanism of the economy development and its resource, environmental influence. And then it gives out relevant ideas about the sustainable development＇s realizing means, motive force and economic model.
文摘Increased neck strength has been linked to a potential decrease in traumatic brain injuries(TBI).The purpose was to determine the efficacy of a neck-strengthening protocol using a novel neck-strengthening device to increase isometric neck strength and rate of force development(RFD).Utilizing self-generated centripetal force,participants trained for 14 weeks.A linear mixed model was used to analyze the relationship between post-assessment measurements and pre-assessments measurements,while accounting for repeated measure random effect at the individual level,and a regular random error term.RFD values were 4.344 times higher in the clockwise direction and 5.978 times higher in the counterclockwise direction when comparing pre and post assessment measurements.Isometric neck strength increased significantly(p<0.05)in the cervical extension(p=0.010)and left lateral flexion(p=0.009)directions.The results can be used in strength training and clinical settings to potentially reduce the incidence of TBI.
基金supported jointly by the CAS Programme (Grant No. XDA11010402)the National Basic Research Program of China (Grant Nos. 2010CB950403, 2012CB417203)+1 种基金the National Natural Science Foundation of China (Grant No. 41275088)the Project founded by China Postdoctoral Science Foundation.
文摘The NCEP/NCAR R1 reanalysis data are employed to investigate the impact of forced and inertial instability in the lower troposphere over the Arabian Sea on the onset process of Indian summer monsoon(ISM),and to reveal the important role of zonal advection of zonal geostrophic momentum played in the forced unstable convection.Results show that during the ISM onset the zero absolute vorticity contour(??=0)shifts northward due to the strong cross-equatorial pressure gradient in the lower troposphere over southern Arabian Sea.Thus a region with negative absolute vorticity is generated near the equator in the northern hemisphere,manifesting the evident free inertial instability.When a southerly passes through this region,under the influence of friction a lower convergence that facilitates the convection flourishing at the lower latitudes appears to the north of zero absolute vorticity contour.However,owing to such a traditional inertial instability,the convection is confined near the equator which does not have direct influence on the ISM onset.On the contrary in the region to the north of the zero absolute vorticity contour and to the south of the low pressure center near the surface,although the atmosphere there is inertially stable,the lower westerly jet can develop and bring on the apparent zonal advection of zonal geostrophic momentum.Both theoretical study and diagnosing analysis present that such a zonal advection of geostrophic momentum is closely associated with the zonal asymmetric distribution of meridional land-sea thermal contrast,which induces a convergence center near and further north of the westerly jet in the lower troposphere over the southwestern coast of the Indian Peninsula,providing a favorable lower circulation for the ISM onset.It illustrates that the development of convection over the Arabian Sea in late spring and early summer is not only due to the frictional inertial instability but also strongly affected by the zonal asymmetric distribution of land-sea thermal contrast.Moreover,before the ISM onset due to the eastward development of the South Asian High(SAH)in the upper troposphere,high potential vorticity is transported to the region over the Arabian Sea.Then a local trumpet-shaped stream field is generated to cause the evident upper divergence-pumping effect which favors the ISM onset.When the upper divergence is vertically coupled with the lower convergence resulted from the aforementioned forced unstable convection development near the southwestern coast of Indian Peninsula,the atmospheric baroclinic unstable development is stimulated and the ISM onset is triggered.
文摘Purpose： The present study aimed to examine the effect of static stretching （SS） and a sport-specific dynamic stretching （DS） session at two specific post-stretch time intervals in highly trained female athletes （age 19.90 ± 1.60 years; height 1.80 ±0.06 m; mass 76.87 ± 9.95 kg） on kinetic parameters of peak force, time-to-takeoff, and rate of force development. Methods： The data were collected over 3 days （randomized within subject design with control session）. Following each stretch session （SS vs. DS vs. control） of equal duration （7 min total： 30 s per targeted muscle group） participants performed countermovement jumping on a force platform at 1 and 15 rain after stretching. Results： The DS session significantly improved upon kinetic variables of rate of force development, peak force, and time-to-takeoffrelative to SS at 1 min after stretching. No significant effect was found at 15 min. Conclusion： Together these findings suggest that when training and competing to jump quickly and maximally the female athlete should incorporate DS instead of SS as part of their pre-competition warm-up, but conduct performance within 15 min of their warm-up to elicit maximal gains
文摘Purpose： Long-term training specificity is thought to alter performance in tests evaluating strength and power production capability. The aim of the present study was to provide additional information to the limited existing knowledge concerning the possible differences of the force/time profile of squat jumping among different groups of young female athletes. Methods： One hundred and seventy-three adult women （20.1 ± 2.8 years, 1.71 ± 0.09 m, 65.6 ± 10.3 kg, mean± SD for age, height, and mass, respectively） engaged in track and field （TF）, volleyball （VO）, handball （HA）, basketball （BA）, and physical education students （PE） executed maximal squat jumps （SQJ） on a force plate. Pearson＇s correlation was used to identify the relationship between SQJ performance, the anthropometric characteristics and the biomechanical parameters. Differences concerning the biomechanical parameters among groups were investigated with analysis of variance, while the force- （FPD） or time- （TPD） dependency of SQJ execution was examined using principal components analysis （PCA）. Results： SQJ was unrelated to body height but significantly correlated with body mass （r = -0.26, p = 0.001）. TF jumped higher and produced larger peak body power output compared to all the other groups （p 〈 0.05）. All athletes were superior to PE since they performed the SQJ with a longer （p 〈 0.05） vertical body center of mass trajectory during the propulsion phase. PCA results revealed that TF significantly differentiated than the other groups by relying on FPD. Conclusion： Various different profiles of FPD and TPD were detected due to different sporting background in young female athletes. Since TF superiority in SQJ was relied on the larger power production and a greater FPD, female indoor team sport athletes are suggested to execute jumping exercises adopting the jumping strategies utilized by TE
文摘The authors of the original research entitled“Acute Effects of a Fatiguing Protocol on Peak Force and Rate of Force Development of the Hamstring Muscles in Soccer Players”[2]thank the authors for diligently examining our manuscript and raising some key points in their letter to the Editor.
文摘Although the ability to produce force rapidly is an indispensable characteristic of optimal health and performance, screening for this very critical parameter of strength is difficult because of clinician time constraints. The purpose this study was to investigate relationships between peak torque （PT） and rate of torque development （RTD） at 0-30, 0-50, 0-100, and 0-200 ms in female collegiate soccer athletes. Seventeen female collegiate soccer athletes were recruited. Isometric PT and RTD were collected at the hip abductors （AB）, hip adductors （AD）, knee extensors （KE） and knee flexors （KF）. The coefficients of determination were calculated to evaluate the association between PT and RTD. Normalized AB, AD and KF PT were significantly correlated to RTD at 0-30, 0-50, 0-100 and 0-200 ms, while KEPT was only significantly correlated to RTD at 0-100 and 0-200 ms. The results of this study indicate that PT is a viable, indirect indicator of early late phase RTD at separate time intervals at the AB, AD and KF. However, it is likely that other physiological factors coupled with PT are required to provide information on the rapid force production capabilities of the KFs and KEs based on the percent of common variance observed.
文摘We compared the effects of low intensity concentric(CON)and eccentric(ECC)exercise on the force and neural responses of the dominant(exercised)elbow flexors(EFs),and studied if these conditions could induce cross-over effects to the contralateral(non-exercised)EFs.Fifteen subjects(8 males)completed all conditions(CON and ECC:6 sets of low intensity exercise to failure;control:rest)in separate visits with a randomized order.Maximal isometric force and electromyography(EMG)of the dominant and contralateral EFs were assessed at pre,immediate-,24-,and 48-h-post.Two-factor(condition and time)linear mixed-model analyses were performed to examine the force and EMG responses.Immediately post CON,contralateral EFs force was significantly(p=0.026)higher(12.41%)than control,but no cross-over effects regarding the neural responses were observed.Immediately post ECC,dominant EFs force was significantly lower in ECC,compared to CON(p=0.003)and control(p<0.001).This force remained depressed at 24-and 48-h post ECC,when compared to CON(p<0.001)and control(p<0.001).Our data suggests that submaximal unilateral exercises are not likely to impair contralateral muscle strength performance.Instead,concentric exercises may acutely improve muscle strength for the contralateral limb.However,this effect is not explained by changes in muscle excitation.
文摘Rate of force development(RFD)and impulse(IMP)are important mechanical measures of muscular performance but are relatively unused within the rehabilitation and performance community.Due principally to access to low-cost testing devices and understanding the utility of these measures.The aim of this study therefore was to quantify the reliability of various force-time variables using load-cell technology collected via isometric knee extension whilst constrained in an isokinetic device(CON90)or unconstrained on a physiotherapy plinth at 60 and 90 degree angles(UNCON60 and UNCON90).Thirty-two volunteers had their peak force(PF),RFD,peak RFD(PRFD),and IMP assessed across three protocols.For all variables,UNCON60 had the largest variability across all measures.PF and PRFD were found to have small variability(ICC>0.67 and CV<10%).With regards to RFD 2080 all three protocols were found to have moderate variability all ICCs above 0.75,however,all CVs were greater than 10%ranging from~11%-22%.Finally,IMP 2080 was found to have moderate variability for both CON90 and UNCON90,the absolute consistency once more greater than 10%(~11%-25%).Using the constrained and unconstrained protocols,PF and PRFD can be measured reliably between trials with 90 degree knee position.
文摘Science and technology are foremost productive forces,while industry is the cornerstone of the national economy.The pursuit of integrated advancement in technological and industrial innovation is,therefore,critical to the development of new quality productive forces and the entire Chinese modernization agenda.
文摘In developing society＇s productive forces, the construction of an ecological civilization must conform to nature, stress civilized development, protect natural ecosystems, pursue social reproduction in accordance with the rules of ecological economy, gradually change the traditional high-carbon and linear mode of production of large-scale machine industry into a low-carbon and circular mode of production, and satisfy the demands of a virtuous cycle of man-made ecosystems through scientific development.
