Background:Residual force enhancement(rFE),defined as increased isometric force following active lengthening compared to a fixed-end isometric contraction at the same muscle length and level of activation,is present a...Background:Residual force enhancement(rFE),defined as increased isometric force following active lengthening compared to a fixed-end isometric contraction at the same muscle length and level of activation,is present across all scales of muscle.While rFE is always present at the cellular level,often rFE"non-re sponders"are observed during joint-level voluntary contractions.Methods:We compared rFE between the joint level and single fiber level(vastus lateralis biopsies)in 16 young males.In vivo voluntary kneeextensor rFE was measured by comparing steady-state isometric torque between a stretch-hold(maximal activation at 150°,stretch to 70°,hold)and a fixed-end isometric contraction,with ultrasonographic recording of vastus lateralis fascicle length(FL).Fixed-end contractions were performed at 67.5°,70.0°,72.5°,and 75.0°;the joint angle that most closely matched FL of the stretch-hold contraction's isometric steady-state was used to calculate rFE.The starting and ending FLs of the stretch-hold contraction were expressed as%optimal FL,determined via torqueangle relationship.Resu lts:In single fiber experiments,the starting and ending fiber lengths were matched relative to optimal length determined from in vivo testing,yielding an average sarcomere excursion of~2.2-3.4μm.There was a greater magnitude of rFE at the single fiber(~20%)than joint level(~5%)(p=0.004),with"non-re sponders"only observed at the joint level.Conclusion:By comparing rFE across scales within the same participants,we show the development of the rFE non-responder phenomenon is upstream of rFE's cellular mechanisms,with rFE only lost rather than gained when scaling from single fibers to the joint level.展开更多
To the editor:Peer workers-people with personal experiences of using mental health services,trained to provide support to others currently using similar services--are increasingly integrated into the workforce of ment...To the editor:Peer workers-people with personal experiences of using mental health services,trained to provide support to others currently using similar services--are increasingly integrated into the workforce of mental health systems internationally.展开更多
The aging of the global population is accelerating,and the ques-tion of how to extend the human life span-especially a healthy life span-has become a hot research topic at home and abroad.As people age,the structure a...The aging of the global population is accelerating,and the ques-tion of how to extend the human life span-especially a healthy life span-has become a hot research topic at home and abroad.As people age,the structure and function of various tissues and organs in the body will successively undergo varying degrees of decline;the rate and manifestation of the aging of each tissue and organ also differ.This decline is the root cause of the poor disease resis-tance of older people,making them prone to infections and various chronic diseases.Although studies have reported the 12 classic hallmarks of aging,and many cutting-edge research methods have been used to map the cellular atlas of aging,scholars have not been able to elucidate the specific changes in and molecular mecha-nisms of the aging of specific organs or the interactions between various tissues and organs,limiting the implementation of precise interventions against aging.展开更多
The advent of the metaverse,including virtual reality,augmented reality,andartificial intelligence,is an undeniable issue that health care scientists need toupdate.It influences all fields of knowledge,interpersonal r...The advent of the metaverse,including virtual reality,augmented reality,andartificial intelligence,is an undeniable issue that health care scientists need toupdate.It influences all fields of knowledge,interpersonal relationships,andhealth.Regarding mental health since the post-coronavirus disease 2019 pandemic,it is necessary to consider and understand the potential,possibilities,weaknesses,and consequences arising from and provided by this new scenario.Due tothe increasing need for mental health monitoring and care,mental health treatmentsrequire in-depth training and preparation to achieve the maximum use of themetaverse advantages and possibilities.Currently,very little is known about theeffectiveness of remote mental health treatment,but it is certainly suggested thataccessibility and the characteristics associated with the use of metaverse technologiesmay represent new horizons for accessibility and approach tools,as long asmore studies are carried out and more evidence is collected to develop accurateguidelines,safe training,solve ethical concerns,and overcome limitations.展开更多
基金supported by the Natural Sciences and Engineering Research Council of Canada(NSERC,Grant No.RGPIN-2024-03782).
文摘Background:Residual force enhancement(rFE),defined as increased isometric force following active lengthening compared to a fixed-end isometric contraction at the same muscle length and level of activation,is present across all scales of muscle.While rFE is always present at the cellular level,often rFE"non-re sponders"are observed during joint-level voluntary contractions.Methods:We compared rFE between the joint level and single fiber level(vastus lateralis biopsies)in 16 young males.In vivo voluntary kneeextensor rFE was measured by comparing steady-state isometric torque between a stretch-hold(maximal activation at 150°,stretch to 70°,hold)and a fixed-end isometric contraction,with ultrasonographic recording of vastus lateralis fascicle length(FL).Fixed-end contractions were performed at 67.5°,70.0°,72.5°,and 75.0°;the joint angle that most closely matched FL of the stretch-hold contraction's isometric steady-state was used to calculate rFE.The starting and ending FLs of the stretch-hold contraction were expressed as%optimal FL,determined via torqueangle relationship.Resu lts:In single fiber experiments,the starting and ending fiber lengths were matched relative to optimal length determined from in vivo testing,yielding an average sarcomere excursion of~2.2-3.4μm.There was a greater magnitude of rFE at the single fiber(~20%)than joint level(~5%)(p=0.004),with"non-re sponders"only observed at the joint level.Conclusion:By comparing rFE across scales within the same participants,we show the development of the rFE non-responder phenomenon is upstream of rFE's cellular mechanisms,with rFE only lost rather than gained when scaling from single fibers to the joint level.
基金funded by National Institute for Health Research(NIHR)(RP-PG-1212-20019)。
文摘To the editor:Peer workers-people with personal experiences of using mental health services,trained to provide support to others currently using similar services--are increasingly integrated into the workforce of mental health systems internationally.
文摘The aging of the global population is accelerating,and the ques-tion of how to extend the human life span-especially a healthy life span-has become a hot research topic at home and abroad.As people age,the structure and function of various tissues and organs in the body will successively undergo varying degrees of decline;the rate and manifestation of the aging of each tissue and organ also differ.This decline is the root cause of the poor disease resis-tance of older people,making them prone to infections and various chronic diseases.Although studies have reported the 12 classic hallmarks of aging,and many cutting-edge research methods have been used to map the cellular atlas of aging,scholars have not been able to elucidate the specific changes in and molecular mecha-nisms of the aging of specific organs or the interactions between various tissues and organs,limiting the implementation of precise interventions against aging.
文摘The advent of the metaverse,including virtual reality,augmented reality,andartificial intelligence,is an undeniable issue that health care scientists need toupdate.It influences all fields of knowledge,interpersonal relationships,andhealth.Regarding mental health since the post-coronavirus disease 2019 pandemic,it is necessary to consider and understand the potential,possibilities,weaknesses,and consequences arising from and provided by this new scenario.Due tothe increasing need for mental health monitoring and care,mental health treatmentsrequire in-depth training and preparation to achieve the maximum use of themetaverse advantages and possibilities.Currently,very little is known about theeffectiveness of remote mental health treatment,but it is certainly suggested thataccessibility and the characteristics associated with the use of metaverse technologiesmay represent new horizons for accessibility and approach tools,as long asmore studies are carried out and more evidence is collected to develop accurateguidelines,safe training,solve ethical concerns,and overcome limitations.
