Sarcomerogenesis,the addition of serial sarcomeres in skeletal muscle myofibrils and fibres,is a natural occurrence during growth and maturation of animals,including humans.However,the detailed mechanisms that allow f...Sarcomerogenesis,the addition of serial sarcomeres in skeletal muscle myofibrils and fibres,is a natural occurrence during growth and maturation of animals,including humans.However,the detailed mechanisms that allow for sarcomerogenesis are not fully understood.In some diseases,such as cerebral palsy in children,sarcomerogenesis appears to be inhibited or at least reduced,1,2 often causing severe restrictions in muscle and joint function.展开更多
Background:Insufficient physical activity and prolonged sedentary behavior have emerged as major global public health challenges.Short bouts(≤10 min)of accumulated exercise(SBAE)throughout the day may be a promising ...Background:Insufficient physical activity and prolonged sedentary behavior have emerged as major global public health challenges.Short bouts(≤10 min)of accumulated exercise(SBAE)throughout the day may be a promising strategy to mitigate the adverse effects of prolonged sitting and promote physical activity,ultimately promoting overall health.However,previous ambiguity in defining this concept has resulted in a fragmented and inconsistent evidence base,impeding practical applications,the development of guidelines,and policymaking.The purpose of this study is to establish an operational definition of SBAE by synthesizing systematic reviews and research trials alongside an expert consensus.Additionally,it seeks to evaluate acute and long-term efficacy and feasibility,providing evidence-based recommendations for practice and future research directions.Methods:A literature search was performed across PubMed and Web of Science,followed by systematic screening and summarization of eligible studies based on predefined inclusion criteria.Inclusion criteria encompassed various modes/types of SBAE(bouts lasting≤10 min,performed multiple times daily with≥30 min intervals);both aerobic and resistance exercise were considered.Relevant systematic reviews and research trials were included.Methodological quality,risk of bias,and evidence certainty were assessed.Expert consensus was obtained through a survey to evaluate recommendations and agreement levels on findings.Results:After analyzing 27 systematic reviews,135 research studies,and an expert consensus involving 48 researchers from 11 countries,SBAE is defined as any exercise mode of activity,regardless of intensity,that is accumulated in either continuous or intermittent bouts lasting≤10 min per session(including multiple intermittent sets)that are performed multiple times(≥2 sessions/day)per day,with intervals of≥30 min between bouts or otherwise sufficient time for recovery.When used to interrupt prolonged periods of sedentary time,SBAE mitigates the acute adverse effects of sedentary behavior on more than 10 clinical biomarkers of endocrine,cardiovascular,and brain health/function among adults of diverse ages and conditions.Moreover,SBAE was superior for improving acute glycemic control compared to a single continuous exercise session.As a long-term intervention(average of 11 weeks),SBAE can improve over 20 health outcomes,including peak oxygen uptake,resting blood pressure,and metabolic health.Additionally,SBAE might be more effective than continuous exercise for improving longer-term glycemic control and body composition.Long-term completion rates for SBAE interventions are generally high(95%),with low dropout rates(12%)and high adherence rates even without supervision(85%),and its safety has been preliminarily validated.Conclusion:An operational definition of SBAE is provided along with its classification and acute and long-term efficacy.Practical exercise prescription recommendations and evidence-based strategies for various populations and contexts are provided.Future research should focus on generating high-quality evidence for SBAE in 5 key areas:quantification and monitoring,population-specific responses,optimization of exercise prescriptions,intervention efficacy,and practical implementation.Additionally,addressing policy,environmental,and promotional barriers is crucial for transitioning from expert consensus to public consensus,and for facilitating the application of this strategy in real-world environments.展开更多
Endurance athletic performance is highly related to a number of fiactors that can be altered through altitude and hypoxic training including increases in erythrocyte volume, maximal aerobic exercise capacity, capillar...Endurance athletic performance is highly related to a number of fiactors that can be altered through altitude and hypoxic training including increases in erythrocyte volume, maximal aerobic exercise capacity, capillary density, and economy. Physiological adaptations in response to acute and chronic exposure to hypoxic environments are well documented and range from short-term detrimental effects to longer-term adaptations that can improve performance at altitude and in sea-level competitions. Many altitude and hypoxic training protocols have been developed, employing various combinations of living and training at sea-level, low, moderate, and high altitudes and utilizing natural and artificial altitudes, with varying degrees of effectiveness. Several factors have been identified that are associated with individual responses to hypoxic training, and techniques for identifying those athletes most likely to benefit from hypoxic trairdng continue to be investigated. Exposure to sufficiently high altitude （2000-3000 m） for more than 12 h/day, while training at lower altitudes, for a minimum of 21 days is recommended. Timing of altitude training related to competition remains under debate, although general recommendations can be considered.展开更多
Natural adult aging is associated with many functional impairments of the human neuromuscular system.One of the more observable alterations is the loss of contractile muscle mass,termed sarcopenia.The loss of muscle m...Natural adult aging is associated with many functional impairments of the human neuromuscular system.One of the more observable alterations is the loss of contractile muscle mass,termed sarcopenia.The loss of muscle mass occurs primarily due to a progressive loss of viable motor units,and accompanying atrophy of remaining muscle fibers.Not only does the loss of muscle mass contribute to impaired function in old age,but alterations in fiber type and myosin heavy chain isoform expression also contribute to weaker,slower,and less powerful contracting muscles.This review will focus on motor unit loss associated with natural adult aging,age-related fatigability,and the age-related differences in strength across contractile muscle actions.展开更多
Space travel since the 1960s has led to a number of physiological alterations to homeostasis in astronauts. Extensive variation in the pattern of responses observed has led a concerted effort to develop countermeasure...Space travel since the 1960s has led to a number of physiological alterations to homeostasis in astronauts. Extensive variation in the pattern of responses observed has led a concerted effort to develop countermeasures to overcome such changes and restore homeostasis, and thus “health” is defined as more “Earth-like”. These adaptations to a space environment by a species which evolved and normally exists in the 1 g environment, the geomagnetic field, and background radiation of Earth are viewed as threats to health as defined by the conditions of Earth. Exposure to space can lead to alterations in genomic stability and epigenetic signatures, alterations which could redefine “health” and responses to risks for loss of health for those who will return to Earth. In contrast, in the future individuals born in non-Earth space environments will likely develop an integrated metabolic set point defined by those conditions. They will thus be shaped by both the local environments, and space-associated genomic/epigenomic alterations to their parents. Therefore, such an altered set point for those born and raised in non-Earth space environments will potentially have physiological and molecular consequences which may lead to either new evolutionary adaptation, or to compromise of long term health due to drastically altered set points for integrated physiologic function which is at odds with the evolutionary history of humans. The implications of the two options will be critical for defining “health” in altered environments encountered during space ventures, as well as providing insights into the regulation of human integrity at the physiological level. Therefore, the definition of “health” is dependent on the boundary conditions surrounding development and maturation, and is a dynamic concept.展开更多
Sports equipment such as athletic footwear is designed to prevent injury and/or improve performance. There is limited research about the effects of foot orthoses or shoe insoles on performance improvement via enhanced...Sports equipment such as athletic footwear is designed to prevent injury and/or improve performance. There is limited research about the effects of foot orthoses or shoe insoles on performance improvement via enhanced energetics. One possible solution to improve the energy storage and return of athletic footwear is to utilize a carbon fiber shoe insole （CFI） optimally tuned for the human body-footwear system. The purpose of this study was to examine the effects of a CFI on athletic performance. Thirty-four （15 males, 19 females） collegiate athletes performed a vertical jump, a pro agility test, and a 10-yard sprint while wearing normal athletic footwear and footwear incorporating a CFI. Vertical jump height was measured using a commercial Vertec device; pro agility test and 10-yard sprint times were measured using a laser timing system. The use of a CFI resulted in significant improvements in the vertical jump （＋2.5%, p = 0.012） and the 10-yard sprint （＋1.5%, p = 0.020）, but not in the pro agility test. These results demonstrated a CFI can enhance speed/acceleration and power in collegiate athletes. Individual anatomical and biomechanical differences may influence the appropriate CFI stiffness required for each athlete to achieve maximal performance in sports involving running, jumping, and change-of-direction.展开更多
With the Rio Olympics just a few months past,we remember the excitement,the incredible performances,and the controversies.As happens so often,the Olympic Games focus attention not only on athletic achievements but als...With the Rio Olympics just a few months past,we remember the excitement,the incredible performances,and the controversies.As happens so often,the Olympic Games focus attention not only on athletic achievements but also on how athletes may reach ever-increasing levels of performance.Doping,medical展开更多
Objective:We reviewed and appraised the existing evidence of in vivo manifestations of residual force enhancement in human skeletal muscles and assessed,through a meta-analysis,the effect of an immediate history of ec...Objective:We reviewed and appraised the existing evidence of in vivo manifestations of residual force enhancement in human skeletal muscles and assessed,through a meta-analysis,the effect of an immediate history of eccentric contraction on the subsequent torque capacity of voluntary and electrically evoked muscle contractions.Methods:Our search was conducted from database inception to May 2020.Descriptive information was extracted from,and quality was assessed for,45 studies.Meta-analyses and metaregressions were used to analyze residual torque enhancement and its dependence on the angular amplitude of the preceding eccentric contraction.Results:Procedures varied across studies with regards to muscle group tested,angular stretch amplitude,randomization of contractions,time window analyzed,and verbal command.Torque capacity in isometric(constant muscle tendon unit length and joint angle)contractions preceded by an eccentric contraction was typically greater compared to purely isometric contractions,and this effect was greater for electrically evoked muscle contractions than voluntary contractions.Residual torque enhancement differed across muscle groups for the voluntary contractions,with a significant enhancement in torque observed for the adductor pollicis,ankle dorsiflexors,ankle plantar flexors,and knee extensors,but not for the elbow and knee flexors.Meta-regressions revealed that the angular amplitude of the eccentric contraction(normalized to the respective joints full range of motion)was not associated with the residual torque enhancement observed.Conclusion:There is evidence of residual torque enhancement for most,but not all,muscle groups,and residual torque enhancement is greater for electrically evoked than for voluntary contractions.Contrary to our hypothesis,and contrary to generally accepted findings on isolated muscle preparations,residual torque enhancement in voluntary and electrically evoked contractions does not seem to depend on the angular amplitude of the preceding eccentric contraction.展开更多
1.Background When searching for the term“muscle power”on Google Scholar,about 3.7 million hits come up in 60 ms,and for the past 3 years,there were approximately 225 yearly peer-reviewed publications dealing with mu...1.Background When searching for the term“muscle power”on Google Scholar,about 3.7 million hits come up in 60 ms,and for the past 3 years,there were approximately 225 yearly peer-reviewed publications dealing with muscle power.Muscle power has been used to assess and predict athletic performance,to determine muscle rehabilitation following injury or disease,to measure functional decline as occurs in aging,and many other topics.展开更多
Purpose:This study aimed to examine the linkage between gut microbiome taxa and exercise-induced inflammation.Methods:Twenty-five cyclists provided 4 stool samples during a 10-week period and cycled vigorously for 2.25...Purpose:This study aimed to examine the linkage between gut microbiome taxa and exercise-induced inflammation.Methods:Twenty-five cyclists provided 4 stool samples during a 10-week period and cycled vigorously for 2.25 h at 67%maximal oxygen uptake(VO2max)in a laboratory setting.Blood samples were collected pre-and post-exercise,with additional samples collected at 1.5-h,3-h,and 24-h post exercise.Primary outcomes included stool microbiome composition and alpha diversity via whole genome shotgun(WGS)sequencing(averaged from 4 stool samples)and a targeted panel of 75 plasma oxylipins.A total of 5719 taxa were identified,and the 339 that were present in more than 20%of stool samples were used in the analysis.Alpha diversity was calculated by evenness,and the Analysis of Composition of Microbiomes(ANCOM)differential abundance analysis was performed using Quantitative Insights Into Microbial Ecology-2(QIIME2).A composite variable was calculated from 8 pro-inflammatory oxylipins generated from arachidonic acid(ARA)and cytochrome P-450(CYP).Results:ARA-CYP oxylipins were significantly elevated for at least 3-h post-exercise(p<0.001);they were strongly and positively related to Prevotella copri(P.copri)abundance(R2=0.676,p<0.001)and negatively related to gut microbiome alpha diversity(R2=0.771,p<0.001).Conclusion:This analysis revealed for thefirst time a novel,positive relationship between gut microbiome P.copri abundance in cyclists and post-exercise pro-inflammatory oxylipins.These data demonstrate that about two-thirds of the wide variance in inflammation following prolonged and intensive exercise is largely explained by the abundance of a single gut bacterial species:P.copri.展开更多
Purpose:This study aimed to evaluate the relationship between peak tibial acceleration and peak ankle joint contact forces in response to stride length manipulation during level-ground running.Methods:Twenty-seven phy...Purpose:This study aimed to evaluate the relationship between peak tibial acceleration and peak ankle joint contact forces in response to stride length manipulation during level-ground running.Methods:Twenty-seven physically active participants ran 10 trials at preferred speed in each of 5 stride length conditions:preferred,±5%,and±10%of preferred stride length.Motion capture,force platform,and tibial acceleration data were directly measured,and ankle joint contact forces were estimated using an inverse-dynamics-based static optimization routine.Results:In general,peak axial tibial accelerations(p<0.001)as well as axial(p<0.001)and resultant(p<0.001)ankle joint contact forces increased with stride length.When averaged within the 10 strides of each stride condition,moderate positive correlations were observed between peak axial acceleration and joint contact force(r=0.49)as well as peak resultant acceleration and joint contact force(r=0.51).However,37%of participants illustrated either no relationship or negative correlations.Only weak correlations across participants existed between peak axial acceleration and joint contact force(r=0.12)as well as peak resultant acceleration and ankle joint contact force(r=0.18)when examined on a step-by-step basis.Conclusion:These results suggest that tibial acceleration should not be used as a surrogate for ankle joint contact force on a step-by-step basis in response to stride length manipulations during level-ground running.A 10-step averaged tibial acceleration metric may be useful for some runners,but an initial laboratory assessment would be required to identify these individuals.展开更多
This study retrospectively evaluated data from an athlete management system on the impact of a 6-week,12-session risk-reduction athletic development training program on maximal isometric strength in post-rehabilitativ...This study retrospectively evaluated data from an athlete management system on the impact of a 6-week,12-session risk-reduction athletic development training program on maximal isometric strength in post-rehabilitative and healthy men and women.Maximal isometric quadriceps and hamstrings strength were evaluated bilaterally before and after the training program.Out of 55 athletes that had participated in the program,a total of 37 athletes'(13-28 years old)recorded outcomes were utilized in analyses.Thirty-one athletes had undergone rehabilitation(post-rehabilitative athletes)after orthopedic knee surgeries.Six athletes with no previous surgeries performed(healthy athletes)also completed the 6-week program.Repeated measures analyses of variance(leg×time)assessed changes in quadriceps and hamstrings strength at an alpha of p≤0.05.There was a main effect for time where the post-rehabilitative athletes’quadriceps and hamstrings strength increased by(mean difference±standard error)(4.2±0.7)kg(p<0.01)and(4.5±0.9)kg(p<0.01)respectively,with legs(operative[OP])and (non-operative[NOP])combined.With time points combined,the OP limb was weaker than the NOP limb for quadriceps strength by(2.9±0.7)kg(p<0.01)with no differences in hamstrings strength.For the healthy athletes,there were no changes for quadriceps strength and hamstring strength improved across time by(5.3±1.4)kg(p=0.01)with legs combined.In conclusion,there were improvements in post-rehabilitative and healthy athletes’isometric strength after the training program.However,between-limb strength asymmetries were still apparent in the post-rehabilitation cohort.展开更多
This review summarizes research discoveries within 4 areas of exercise immunology that have received the most attention from investigators :(1) acute and chronic effects of exercise on the immune system,(2) clinical b...This review summarizes research discoveries within 4 areas of exercise immunology that have received the most attention from investigators :(1) acute and chronic effects of exercise on the immune system,(2) clinical benefits of the exercise—immune relationship,(3) nutritional influen?ces on the immune response to exercise, and(4) the effect of exercise on immunosenescence. These scientific discoveries can be organized into distinctive time periods: 1900-1979, which focused on exercise-induced changes in basic immune cell counts and function; 1980-1989, during which seminal papers were published with evidence that heavy exertion was associated with transient immune dysfunction, elevated inflammatory biomarkers,and increased risk of upper respiratory tract infections; 1990-2009, when additional focus areas were added to the field of exercise immunology including the interactive effect of nutrition, effects on the aging immune system, and inflammatory cytokines; and 2010 to the present, when technological advances in mass spectrometry allowed system biology approaches(i.e., metabolomics, proteomics, lipidomics, and microbiome characterization) to be applied to exercise immunology studies. The future of exercise irmmunology will take advantage of these technologies to provide new insights on the interactions between exercise, nutrition, and immune function, with application down to the person?alized level. Additionally, these methodologies will improve mechanistic understanding of how exercise-induced immune perturbations reduce the risk of common chronic diseases.展开更多
Several decades of research in the area of exercise immunology have shown that the immune system is highly responsive to acute and chronic exercise training.Moderate exercise bouts enhance immunosurveillance and when ...Several decades of research in the area of exercise immunology have shown that the immune system is highly responsive to acute and chronic exercise training.Moderate exercise bouts enhance immunosurveillance and when repeated over time mediate multiple health benefits.Most of the studies prior to 2010 relied on a few targeted outcomes related to immune function.During the past decade,technologic advances have created opportunities for a multi-omics and systems biology approach to exercise immunology.This article provides an overview of metabolomics,lipidomics,and proteomics as they pertain to exercise immunology,with a focus on immunometabolism.This review also summarizes how the composition and diversity of the gut microbiota can be influenced by exercise,with applications to human health and immunity.Exercise-induced improvements in immune function may play a critical role in countering immunosenescence and the development of chronic diseases,and emerging omics technologies will more clearly define the underlying mechanisms.This review summarizes what is currently known regarding a multi-omics approach to exercise immunology and provides future directions for investigators.展开更多
Physical inactivity is a well-established risk factor for chronic diseases,such as cardiovascular disease,cancer,and diabetes mellitus.There is a growing awareness that physical inactivity should also be regarded as a...Physical inactivity is a well-established risk factor for chronic diseases,such as cardiovascular disease,cancer,and diabetes mellitus.There is a growing awareness that physical inactivity should also be regarded as a risk factor for acute respiratory infections(ARIs).ARIs,such as the common cold,influenza,pneumonia,and coronavirus disease 2019(COVID-19),are among the most pervasive diseases on earth and cause widespread morbidity and mortality.Evidence in support of the linkage between ARIs and physical inactivity has been strengthened during the COVID-19 pandemic because of increased scientific scrutiny.Large-scale studies have consistently reported that the risk for severe COVID-19 outcomes is elevated in cohorts with low physical activity and/or physical fitness,even after adjusting for other risk factors.The lowered risk for severe COVID-19 and other ARIs in physically active groups is attributed to exercise-induced immunoprotective effects,including enhanced surveillance of key immune cells and reduced chronic inflammation.Scientific consensus groups,including those who submitted the Physical Activity Guidelines for Americans,have not yet given this area of research the respect that is due.It is time to add“reduced risk for ARIs”to the“Exercise is Medicine”list of physical activity-related health benefits.展开更多
Maintaining leanness and a physically active lifestyle during adulthood reduces systemic inflammation,an underlying factor in multiple chronic diseases.The anti-inflammatory influence of near-daily physical activity i...Maintaining leanness and a physically active lifestyle during adulthood reduces systemic inflammation,an underlying factor in multiple chronic diseases.The anti-inflammatory influence of near-daily physical activity in lowering C-reactive protein,total blood leukocytes,interleukin-6,and other inflammatory cytokines may play a key role in lowering risk of cardiovascular disease,certain types of cancer,type 2 diabetes,sarcopenia,and dementia.Moderate exercise training causes favorable perturbations in immunity and a reduction in incidence of upper respiratory tract infection(URTI).During each bout of moderate exercise,an enhanced recirculation of immunoglobulins,neutrophils,and natural killer cells occurs that persists for up to 3-h post-exercise.This exercise-induced surge in immune cells from the innate immune system is transient but improves overall surveillance against pathogens.As moderate exercise continues on a near-daily basis for 12-15 weeks,the number of symptoms days with URTI is decreased 25％-50％ compared to randomized sedentary controls.Epidemiologic and animal studies support this inverse relationship between URTI risk and increased physical activity.Copyright(c)2012,Shanghai University of Sport.Production and hosting by Elsevier B.V.All rights reserved.展开更多
In their recent papers in the Journal of Sport and Health Science on hamstring injuries in sprinting,^(1,2)and their corresponding commentaries on each other's research,3,4Yu et al.and Liu et al.proposed different...In their recent papers in the Journal of Sport and Health Science on hamstring injuries in sprinting,^(1,2)and their corresponding commentaries on each other's research,3,4Yu et al.and Liu et al.proposed different views of the mechanisms of muscle injuries in general,and hamstring injuries in sprinting specifically.While Yu et al.^(1,3)argued that muscle injuries are primarily,if not exclusively,caused by muscle strain magnitude in eccentric contractions,and thus hamstring injuries occur primarily展开更多
It is well acknowledged that muscles that are elongated while activated(i.e.,eccentric muscle action)are stronger and require less energy(per unit of force)than muscles that are shortening(i.e.,concentric contraction)...It is well acknowledged that muscles that are elongated while activated(i.e.,eccentric muscle action)are stronger and require less energy(per unit of force)than muscles that are shortening(i.e.,concentric contraction)or that remain at a constant length(i.e.,isometric contraction).Although the cross-bridge theory of muscle contraction provides a good explanation for the increase in force in active muscle lengthening,it does not explain the residual increase in force following active lengthening(residual force enhancement),or except with additional assumptions,the reduced metabolic requirement of muscle during and following active stretch.Aside from the cross-bridge theory,2 other primary explanations for the mechanical properties of actively stretched muscles have emerged:(1)the so-called sarcomere length nonuniformity theory and(2)the engagement of a passive structural element theory.In this article,these theories are discussed,and it is shown that the last of these—the engagement of a passive structural element in eccentric muscle action—offers a simple and complete explanation for many hitherto unexplained observations in actively lengthening muscle.Although by no means fully proven,the theory has great appeal for its simplicity and beauty,and even if over time it is shown to be wrong,it nevertheless forms a useful framework for direct hypothesis testing.展开更多
In many countries,sedentary lifestyle has led to a number of epidemic health problems,including obesity,metabolic syndrome,and associated comorbidities.Countries have performed self-evaluations of the fitness status o...In many countries,sedentary lifestyle has led to a number of epidemic health problems,including obesity,metabolic syndrome,and associated comorbidities.Countries have performed self-evaluations of the fitness status of their people:children,young adults,and the elderly.Policies for increased school-based physical education,and financial展开更多
Purpose This study aimed to investigate if changing the midsole bending stiffness of athletic footwear can affect the onset of lower limb joint work redistribution during a prolonged run.Methods Fifteen trained male r...Purpose This study aimed to investigate if changing the midsole bending stiffness of athletic footwear can affect the onset of lower limb joint work redistribution during a prolonged run.Methods Fifteen trained male runners(10-km time of<44 min)performed 10-km runs at 90%of their individual speed at lactate threshold(i.e.,when change in lactate exceeded 1 mmol/L during an incremental running test)in a control and stiff shoe condition on 2 occasions.Lower limb joint kinematics and kinetics were measured using a motion capture system and a force-instrumented treadmill.Data were acquired every 500 m.Results Prolonged running resulted in a redistribution of positive joint work from distal to proximal joints in both shoe conditions.Compared to the beginning of the run,less positive work was performed at the ankle(approximately 9%;p≤0.001)and more positive work was performed at the knee joint(approximately 17%;p≤0.001)at the end of the run.When running in the stiff shoe condition,the onset of joint work redistribution at the ankle and knee joints occurred at a later point during the run.Conclusion A delayed onset of joint work redistribution in the stiff condition may result in less activated muscle volume,because ankle plantar flexor muscles have shorter muscles fascicles and smaller cross-sectional areas compared to knee extensor muscles.Less active muscle volume could be related to previously reported decreases in metabolic cost when running in stiff footwear.These results contribute to the notion that footwear with increased stiffness likely results in reductions in metabolic cost by delaying joint work redistribution from distal to proximal joints.展开更多
文摘Sarcomerogenesis,the addition of serial sarcomeres in skeletal muscle myofibrils and fibres,is a natural occurrence during growth and maturation of animals,including humans.However,the detailed mechanisms that allow for sarcomerogenesis are not fully understood.In some diseases,such as cerebral palsy in children,sarcomerogenesis appears to be inhibited or at least reduced,1,2 often causing severe restrictions in muscle and joint function.
文摘Background:Insufficient physical activity and prolonged sedentary behavior have emerged as major global public health challenges.Short bouts(≤10 min)of accumulated exercise(SBAE)throughout the day may be a promising strategy to mitigate the adverse effects of prolonged sitting and promote physical activity,ultimately promoting overall health.However,previous ambiguity in defining this concept has resulted in a fragmented and inconsistent evidence base,impeding practical applications,the development of guidelines,and policymaking.The purpose of this study is to establish an operational definition of SBAE by synthesizing systematic reviews and research trials alongside an expert consensus.Additionally,it seeks to evaluate acute and long-term efficacy and feasibility,providing evidence-based recommendations for practice and future research directions.Methods:A literature search was performed across PubMed and Web of Science,followed by systematic screening and summarization of eligible studies based on predefined inclusion criteria.Inclusion criteria encompassed various modes/types of SBAE(bouts lasting≤10 min,performed multiple times daily with≥30 min intervals);both aerobic and resistance exercise were considered.Relevant systematic reviews and research trials were included.Methodological quality,risk of bias,and evidence certainty were assessed.Expert consensus was obtained through a survey to evaluate recommendations and agreement levels on findings.Results:After analyzing 27 systematic reviews,135 research studies,and an expert consensus involving 48 researchers from 11 countries,SBAE is defined as any exercise mode of activity,regardless of intensity,that is accumulated in either continuous or intermittent bouts lasting≤10 min per session(including multiple intermittent sets)that are performed multiple times(≥2 sessions/day)per day,with intervals of≥30 min between bouts or otherwise sufficient time for recovery.When used to interrupt prolonged periods of sedentary time,SBAE mitigates the acute adverse effects of sedentary behavior on more than 10 clinical biomarkers of endocrine,cardiovascular,and brain health/function among adults of diverse ages and conditions.Moreover,SBAE was superior for improving acute glycemic control compared to a single continuous exercise session.As a long-term intervention(average of 11 weeks),SBAE can improve over 20 health outcomes,including peak oxygen uptake,resting blood pressure,and metabolic health.Additionally,SBAE might be more effective than continuous exercise for improving longer-term glycemic control and body composition.Long-term completion rates for SBAE interventions are generally high(95%),with low dropout rates(12%)and high adherence rates even without supervision(85%),and its safety has been preliminarily validated.Conclusion:An operational definition of SBAE is provided along with its classification and acute and long-term efficacy.Practical exercise prescription recommendations and evidence-based strategies for various populations and contexts are provided.Future research should focus on generating high-quality evidence for SBAE in 5 key areas:quantification and monitoring,population-specific responses,optimization of exercise prescriptions,intervention efficacy,and practical implementation.Additionally,addressing policy,environmental,and promotional barriers is crucial for transitioning from expert consensus to public consensus,and for facilitating the application of this strategy in real-world environments.
文摘Endurance athletic performance is highly related to a number of fiactors that can be altered through altitude and hypoxic training including increases in erythrocyte volume, maximal aerobic exercise capacity, capillary density, and economy. Physiological adaptations in response to acute and chronic exposure to hypoxic environments are well documented and range from short-term detrimental effects to longer-term adaptations that can improve performance at altitude and in sea-level competitions. Many altitude and hypoxic training protocols have been developed, employing various combinations of living and training at sea-level, low, moderate, and high altitudes and utilizing natural and artificial altitudes, with varying degrees of effectiveness. Several factors have been identified that are associated with individual responses to hypoxic training, and techniques for identifying those athletes most likely to benefit from hypoxic trairdng continue to be investigated. Exposure to sufficiently high altitude （2000-3000 m） for more than 12 h/day, while training at lower altitudes, for a minimum of 21 days is recommended. Timing of altitude training related to competition remains under debate, although general recommendations can be considered.
基金supported by an operating grant to Dr.Charles Rice from the Natural Sciences and Engineering Research Council of Canada (NSERC)supported by the Canadian Institutes of Health Research (CIHR)+1 种基金the Michael Smith Foundation for Health Research (MSFHR)supported by Alberta Innovates Health Solutions (AIHS)
文摘Natural adult aging is associated with many functional impairments of the human neuromuscular system.One of the more observable alterations is the loss of contractile muscle mass,termed sarcopenia.The loss of muscle mass occurs primarily due to a progressive loss of viable motor units,and accompanying atrophy of remaining muscle fibers.Not only does the loss of muscle mass contribute to impaired function in old age,but alterations in fiber type and myosin heavy chain isoform expression also contribute to weaker,slower,and less powerful contracting muscles.This review will focus on motor unit loss associated with natural adult aging,age-related fatigability,and the age-related differences in strength across contractile muscle actions.
文摘Space travel since the 1960s has led to a number of physiological alterations to homeostasis in astronauts. Extensive variation in the pattern of responses observed has led a concerted effort to develop countermeasures to overcome such changes and restore homeostasis, and thus “health” is defined as more “Earth-like”. These adaptations to a space environment by a species which evolved and normally exists in the 1 g environment, the geomagnetic field, and background radiation of Earth are viewed as threats to health as defined by the conditions of Earth. Exposure to space can lead to alterations in genomic stability and epigenetic signatures, alterations which could redefine “health” and responses to risks for loss of health for those who will return to Earth. In contrast, in the future individuals born in non-Earth space environments will likely develop an integrated metabolic set point defined by those conditions. They will thus be shaped by both the local environments, and space-associated genomic/epigenomic alterations to their parents. Therefore, such an altered set point for those born and raised in non-Earth space environments will potentially have physiological and molecular consequences which may lead to either new evolutionary adaptation, or to compromise of long term health due to drastically altered set points for integrated physiologic function which is at odds with the evolutionary history of humans. The implications of the two options will be critical for defining “health” in altered environments encountered during space ventures, as well as providing insights into the regulation of human integrity at the physiological level. Therefore, the definition of “health” is dependent on the boundary conditions surrounding development and maturation, and is a dynamic concept.
文摘Sports equipment such as athletic footwear is designed to prevent injury and/or improve performance. There is limited research about the effects of foot orthoses or shoe insoles on performance improvement via enhanced energetics. One possible solution to improve the energy storage and return of athletic footwear is to utilize a carbon fiber shoe insole （CFI） optimally tuned for the human body-footwear system. The purpose of this study was to examine the effects of a CFI on athletic performance. Thirty-four （15 males, 19 females） collegiate athletes performed a vertical jump, a pro agility test, and a 10-yard sprint while wearing normal athletic footwear and footwear incorporating a CFI. Vertical jump height was measured using a commercial Vertec device; pro agility test and 10-yard sprint times were measured using a laser timing system. The use of a CFI resulted in significant improvements in the vertical jump （＋2.5%, p = 0.012） and the 10-yard sprint （＋1.5%, p = 0.020）, but not in the pro agility test. These results demonstrated a CFI can enhance speed/acceleration and power in collegiate athletes. Individual anatomical and biomechanical differences may influence the appropriate CFI stiffness required for each athlete to achieve maximal performance in sports involving running, jumping, and change-of-direction.
文摘With the Rio Olympics just a few months past,we remember the excitement,the incredible performances,and the controversies.As happens so often,the Olympic Games focus attention not only on athletic achievements but also on how athletes may reach ever-increasing levels of performance.Doping,medical
文摘Objective:We reviewed and appraised the existing evidence of in vivo manifestations of residual force enhancement in human skeletal muscles and assessed,through a meta-analysis,the effect of an immediate history of eccentric contraction on the subsequent torque capacity of voluntary and electrically evoked muscle contractions.Methods:Our search was conducted from database inception to May 2020.Descriptive information was extracted from,and quality was assessed for,45 studies.Meta-analyses and metaregressions were used to analyze residual torque enhancement and its dependence on the angular amplitude of the preceding eccentric contraction.Results:Procedures varied across studies with regards to muscle group tested,angular stretch amplitude,randomization of contractions,time window analyzed,and verbal command.Torque capacity in isometric(constant muscle tendon unit length and joint angle)contractions preceded by an eccentric contraction was typically greater compared to purely isometric contractions,and this effect was greater for electrically evoked muscle contractions than voluntary contractions.Residual torque enhancement differed across muscle groups for the voluntary contractions,with a significant enhancement in torque observed for the adductor pollicis,ankle dorsiflexors,ankle plantar flexors,and knee extensors,but not for the elbow and knee flexors.Meta-regressions revealed that the angular amplitude of the eccentric contraction(normalized to the respective joints full range of motion)was not associated with the residual torque enhancement observed.Conclusion:There is evidence of residual torque enhancement for most,but not all,muscle groups,and residual torque enhancement is greater for electrically evoked than for voluntary contractions.Contrary to our hypothesis,and contrary to generally accepted findings on isolated muscle preparations,residual torque enhancement in voluntary and electrically evoked contractions does not seem to depend on the angular amplitude of the preceding eccentric contraction.
文摘1.Background When searching for the term“muscle power”on Google Scholar,about 3.7 million hits come up in 60 ms,and for the past 3 years,there were approximately 225 yearly peer-reviewed publications dealing with muscle power.Muscle power has been used to assess and predict athletic performance,to determine muscle rehabilitation following injury or disease,to measure functional decline as occurs in aging,and many other topics.
基金supported by Ocean Spray (https://www. oceanspray.com/)
文摘Purpose:This study aimed to examine the linkage between gut microbiome taxa and exercise-induced inflammation.Methods:Twenty-five cyclists provided 4 stool samples during a 10-week period and cycled vigorously for 2.25 h at 67%maximal oxygen uptake(VO2max)in a laboratory setting.Blood samples were collected pre-and post-exercise,with additional samples collected at 1.5-h,3-h,and 24-h post exercise.Primary outcomes included stool microbiome composition and alpha diversity via whole genome shotgun(WGS)sequencing(averaged from 4 stool samples)and a targeted panel of 75 plasma oxylipins.A total of 5719 taxa were identified,and the 339 that were present in more than 20%of stool samples were used in the analysis.Alpha diversity was calculated by evenness,and the Analysis of Composition of Microbiomes(ANCOM)differential abundance analysis was performed using Quantitative Insights Into Microbial Ecology-2(QIIME2).A composite variable was calculated from 8 pro-inflammatory oxylipins generated from arachidonic acid(ARA)and cytochrome P-450(CYP).Results:ARA-CYP oxylipins were significantly elevated for at least 3-h post-exercise(p<0.001);they were strongly and positively related to Prevotella copri(P.copri)abundance(R2=0.676,p<0.001)and negatively related to gut microbiome alpha diversity(R2=0.771,p<0.001).Conclusion:This analysis revealed for thefirst time a novel,positive relationship between gut microbiome P.copri abundance in cyclists and post-exercise pro-inflammatory oxylipins.These data demonstrate that about two-thirds of the wide variance in inflammation following prolonged and intensive exercise is largely explained by the abundance of a single gut bacterial species:P.copri.
基金funded in part by the Natural Sciences and Engineering Research Council of Canada(RGPIN 024042021 and CGS D-534891-2019)the NSERC CREATE Wearable Technology Research and Collaboration training program(graduate fellowship and undergraduate summer research fellowship).
文摘Purpose:This study aimed to evaluate the relationship between peak tibial acceleration and peak ankle joint contact forces in response to stride length manipulation during level-ground running.Methods:Twenty-seven physically active participants ran 10 trials at preferred speed in each of 5 stride length conditions:preferred,±5%,and±10%of preferred stride length.Motion capture,force platform,and tibial acceleration data were directly measured,and ankle joint contact forces were estimated using an inverse-dynamics-based static optimization routine.Results:In general,peak axial tibial accelerations(p<0.001)as well as axial(p<0.001)and resultant(p<0.001)ankle joint contact forces increased with stride length.When averaged within the 10 strides of each stride condition,moderate positive correlations were observed between peak axial acceleration and joint contact force(r=0.49)as well as peak resultant acceleration and joint contact force(r=0.51).However,37%of participants illustrated either no relationship or negative correlations.Only weak correlations across participants existed between peak axial acceleration and joint contact force(r=0.12)as well as peak resultant acceleration and ankle joint contact force(r=0.18)when examined on a step-by-step basis.Conclusion:These results suggest that tibial acceleration should not be used as a surrogate for ankle joint contact force on a step-by-step basis in response to stride length manipulations during level-ground running.A 10-step averaged tibial acceleration metric may be useful for some runners,but an initial laboratory assessment would be required to identify these individuals.
文摘This study retrospectively evaluated data from an athlete management system on the impact of a 6-week,12-session risk-reduction athletic development training program on maximal isometric strength in post-rehabilitative and healthy men and women.Maximal isometric quadriceps and hamstrings strength were evaluated bilaterally before and after the training program.Out of 55 athletes that had participated in the program,a total of 37 athletes'(13-28 years old)recorded outcomes were utilized in analyses.Thirty-one athletes had undergone rehabilitation(post-rehabilitative athletes)after orthopedic knee surgeries.Six athletes with no previous surgeries performed(healthy athletes)also completed the 6-week program.Repeated measures analyses of variance(leg×time)assessed changes in quadriceps and hamstrings strength at an alpha of p≤0.05.There was a main effect for time where the post-rehabilitative athletes’quadriceps and hamstrings strength increased by(mean difference±standard error)(4.2±0.7)kg(p<0.01)and(4.5±0.9)kg(p<0.01)respectively,with legs(operative[OP])and (non-operative[NOP])combined.With time points combined,the OP limb was weaker than the NOP limb for quadriceps strength by(2.9±0.7)kg(p<0.01)with no differences in hamstrings strength.For the healthy athletes,there were no changes for quadriceps strength and hamstring strength improved across time by(5.3±1.4)kg(p=0.01)with legs combined.In conclusion,there were improvements in post-rehabilitative and healthy athletes’isometric strength after the training program.However,between-limb strength asymmetries were still apparent in the post-rehabilitation cohort.
文摘This review summarizes research discoveries within 4 areas of exercise immunology that have received the most attention from investigators :(1) acute and chronic effects of exercise on the immune system,(2) clinical benefits of the exercise—immune relationship,(3) nutritional influen?ces on the immune response to exercise, and(4) the effect of exercise on immunosenescence. These scientific discoveries can be organized into distinctive time periods: 1900-1979, which focused on exercise-induced changes in basic immune cell counts and function; 1980-1989, during which seminal papers were published with evidence that heavy exertion was associated with transient immune dysfunction, elevated inflammatory biomarkers,and increased risk of upper respiratory tract infections; 1990-2009, when additional focus areas were added to the field of exercise immunology including the interactive effect of nutrition, effects on the aging immune system, and inflammatory cytokines; and 2010 to the present, when technological advances in mass spectrometry allowed system biology approaches(i.e., metabolomics, proteomics, lipidomics, and microbiome characterization) to be applied to exercise immunology studies. The future of exercise irmmunology will take advantage of these technologies to provide new insights on the interactions between exercise, nutrition, and immune function, with application down to the person?alized level. Additionally, these methodologies will improve mechanistic understanding of how exercise-induced immune perturbations reduce the risk of common chronic diseases.
文摘Several decades of research in the area of exercise immunology have shown that the immune system is highly responsive to acute and chronic exercise training.Moderate exercise bouts enhance immunosurveillance and when repeated over time mediate multiple health benefits.Most of the studies prior to 2010 relied on a few targeted outcomes related to immune function.During the past decade,technologic advances have created opportunities for a multi-omics and systems biology approach to exercise immunology.This article provides an overview of metabolomics,lipidomics,and proteomics as they pertain to exercise immunology,with a focus on immunometabolism.This review also summarizes how the composition and diversity of the gut microbiota can be influenced by exercise,with applications to human health and immunity.Exercise-induced improvements in immune function may play a critical role in countering immunosenescence and the development of chronic diseases,and emerging omics technologies will more clearly define the underlying mechanisms.This review summarizes what is currently known regarding a multi-omics approach to exercise immunology and provides future directions for investigators.
文摘Physical inactivity is a well-established risk factor for chronic diseases,such as cardiovascular disease,cancer,and diabetes mellitus.There is a growing awareness that physical inactivity should also be regarded as a risk factor for acute respiratory infections(ARIs).ARIs,such as the common cold,influenza,pneumonia,and coronavirus disease 2019(COVID-19),are among the most pervasive diseases on earth and cause widespread morbidity and mortality.Evidence in support of the linkage between ARIs and physical inactivity has been strengthened during the COVID-19 pandemic because of increased scientific scrutiny.Large-scale studies have consistently reported that the risk for severe COVID-19 outcomes is elevated in cohorts with low physical activity and/or physical fitness,even after adjusting for other risk factors.The lowered risk for severe COVID-19 and other ARIs in physically active groups is attributed to exercise-induced immunoprotective effects,including enhanced surveillance of key immune cells and reduced chronic inflammation.Scientific consensus groups,including those who submitted the Physical Activity Guidelines for Americans,have not yet given this area of research the respect that is due.It is time to add“reduced risk for ARIs”to the“Exercise is Medicine”list of physical activity-related health benefits.
文摘Maintaining leanness and a physically active lifestyle during adulthood reduces systemic inflammation,an underlying factor in multiple chronic diseases.The anti-inflammatory influence of near-daily physical activity in lowering C-reactive protein,total blood leukocytes,interleukin-6,and other inflammatory cytokines may play a key role in lowering risk of cardiovascular disease,certain types of cancer,type 2 diabetes,sarcopenia,and dementia.Moderate exercise training causes favorable perturbations in immunity and a reduction in incidence of upper respiratory tract infection(URTI).During each bout of moderate exercise,an enhanced recirculation of immunoglobulins,neutrophils,and natural killer cells occurs that persists for up to 3-h post-exercise.This exercise-induced surge in immune cells from the innate immune system is transient but improves overall surveillance against pathogens.As moderate exercise continues on a near-daily basis for 12-15 weeks,the number of symptoms days with URTI is decreased 25％-50％ compared to randomized sedentary controls.Epidemiologic and animal studies support this inverse relationship between URTI risk and increased physical activity.Copyright(c)2012,Shanghai University of Sport.Production and hosting by Elsevier B.V.All rights reserved.
文摘In their recent papers in the Journal of Sport and Health Science on hamstring injuries in sprinting,^(1,2)and their corresponding commentaries on each other's research,3,4Yu et al.and Liu et al.proposed different views of the mechanisms of muscle injuries in general,and hamstring injuries in sprinting specifically.While Yu et al.^(1,3)argued that muscle injuries are primarily,if not exclusively,caused by muscle strain magnitude in eccentric contractions,and thus hamstring injuries occur primarily
文摘It is well acknowledged that muscles that are elongated while activated(i.e.,eccentric muscle action)are stronger and require less energy(per unit of force)than muscles that are shortening(i.e.,concentric contraction)or that remain at a constant length(i.e.,isometric contraction).Although the cross-bridge theory of muscle contraction provides a good explanation for the increase in force in active muscle lengthening,it does not explain the residual increase in force following active lengthening(residual force enhancement),or except with additional assumptions,the reduced metabolic requirement of muscle during and following active stretch.Aside from the cross-bridge theory,2 other primary explanations for the mechanical properties of actively stretched muscles have emerged:(1)the so-called sarcomere length nonuniformity theory and(2)the engagement of a passive structural element theory.In this article,these theories are discussed,and it is shown that the last of these—the engagement of a passive structural element in eccentric muscle action—offers a simple and complete explanation for many hitherto unexplained observations in actively lengthening muscle.Although by no means fully proven,the theory has great appeal for its simplicity and beauty,and even if over time it is shown to be wrong,it nevertheless forms a useful framework for direct hypothesis testing.
文摘In many countries,sedentary lifestyle has led to a number of epidemic health problems,including obesity,metabolic syndrome,and associated comorbidities.Countries have performed self-evaluations of the fitness status of their people:children,young adults,and the elderly.Policies for increased school-based physical education,and financial
基金financially supported by the International Society of Biomechanics in Sports Student Mini Research Grant awarded to SC
文摘Purpose This study aimed to investigate if changing the midsole bending stiffness of athletic footwear can affect the onset of lower limb joint work redistribution during a prolonged run.Methods Fifteen trained male runners(10-km time of<44 min)performed 10-km runs at 90%of their individual speed at lactate threshold(i.e.,when change in lactate exceeded 1 mmol/L during an incremental running test)in a control and stiff shoe condition on 2 occasions.Lower limb joint kinematics and kinetics were measured using a motion capture system and a force-instrumented treadmill.Data were acquired every 500 m.Results Prolonged running resulted in a redistribution of positive joint work from distal to proximal joints in both shoe conditions.Compared to the beginning of the run,less positive work was performed at the ankle(approximately 9%;p≤0.001)and more positive work was performed at the knee joint(approximately 17%;p≤0.001)at the end of the run.When running in the stiff shoe condition,the onset of joint work redistribution at the ankle and knee joints occurred at a later point during the run.Conclusion A delayed onset of joint work redistribution in the stiff condition may result in less activated muscle volume,because ankle plantar flexor muscles have shorter muscles fascicles and smaller cross-sectional areas compared to knee extensor muscles.Less active muscle volume could be related to previously reported decreases in metabolic cost when running in stiff footwear.These results contribute to the notion that footwear with increased stiffness likely results in reductions in metabolic cost by delaying joint work redistribution from distal to proximal joints.
