Revisiting the stretch-induced force deficit:A systematic review with multilevel meta-analysis of acute effects

Background:When recommending avoidance of static stretching prior to athletic performance,authors and practitioners commonly refer to available systematic reviews.However,effect sizes(ES)in previous reviews were extracted in major part from studies lacking control conditions and/or prepost testing designs.Also,currently available reviews conducted calculations without accounting for multiple study outcomes,with ES:0.03 to 0.10,which would commonly be classified as trivial.Methods:Since new meta-analytical software and controlled research articles have appeared since 2013,we revisited the available literatures and performed a multilevel meta-analysis using robust variance estimation of controlled prepost trials to provide updated evidence.Furthermore,previous research described reduced electromyography activity—also attributable to fatiguing training routines—as being responsible for decreased subsequent performance.The second part of this study opposed stretching and alternative interventions sufficient to induce general fatigue to examine whether static stretching induces higher performance losses compared to other exercise routines.Results:Including 83 studies with more than 400 ES from 2012 participants,our results indicate a significant,small ES for a static stretch-induced maximal strength loss(ES=0.21,p=0.003),with high magnitude ES(ES=0.84,p=0.004)for stretching durations≥60 s per bout when compared to passive controls.When opposed to active controls,the maximal strength loss ranges between ES:0.17 to0.28,p<0.001 and 0.040 with mostly no to small heterogeneity.However,stretching did not negatively influence athletic performance in general(when compared to both passive and active controls);in fact,a positive effect on subsequent jumping performance(ES=0.15,p=0.006)was found in adults.Conclusion:Regarding strength testing of isolated muscles(e.g.,leg extensions or calf raises),our results confirm previous findings.Nevertheless,since no(or even positive)effects could be found for athletic performance,our results do not support previous recommendations to exclude static stretching from warm-up routines prior to,for example,jumping or sprinting.

Immune consequences of exercise in hypoxia:A narrative review

Immune outcomes are key mediators of many health benefits of exercise and are determined by exercise type,dose(frequency/duration,intensity),and individual characteristics.Similarly,reduced availability of ambient oxygen(hypoxia)modulates immune functions depending on the hypoxic dose and the individual capacity to respond to hypoxia.How combined exercise and hypoxia(e.g.,high-altitude training)sculpts immune responses is not well understood,although such combinations are becoming increasingly popular.Therefore,in this paper,we summarize the impact on immune responses of exercise and of hypoxia,both independently and together,with a focus on specialized cells in the innate and adaptive immune system.We review the regulation of the immune system by tissue oxygen levels and the overlapping and distinct immune responses related to exercise and hypoxia,then we discuss how they may be modulated by nutritional strategies.Mitochondrial,antioxidant,and anti-inflammatory mechanisms underlie many of the adaptations that can lead to improved cellular metabolism,resilience,and overall immune functions by regulating the survival,differentiation,activation,and migration of immune cells.This review shows that exercise and hypoxia can impair or complement/synergize with each other while regulating immune system functions.Appropriate acclimatization,training,and nutritional strategies can be used to avoid risks and tap into the synergistic potentials of the poorly studied immune consequences of exercising in a hypoxic state.

Movement analysis in the diagnosis and management of Parkinson’s disease

Challenges in the diagnosis and treatment of Parkinson’s disease:Parkinson’s disease(PD)is an increasingly prevalent neurodegenerative disease,at first sight primarily characterized by motor symptoms,although non-motor symptoms also constitute a major part of the overall phenotype.Clinically,this disease cannot be diagnosed reliably until a large part of the vulnerable dopaminergic neurons has been irretrievably lost,and the disease progresses inexorably.New biological criteria for PD have been proposed recently and might eventually improve early diagnosis,but they require further validation,and their use will initially be restricted to a research environment(Darweesh et al.,2024).

Korea Institute of Sport Science:Past,Present and Future

Introduction Korea Institute of Sport Science (KISS,formerly named as Korea Sport Science Institute:KSSI) was established on December 29th,1980 to perform research and provide support for better performance of the national athletes.KISS had clear objective of supporting scientifi c training of national athletes for successful hosting of 1986 Asian Games and 1988 Olympics,both were to be held in Seoul,Korea. The objective was successfully achieved with strong support from the government.

Adherence to 24-hour movement guidelines in children with mental,behavioral,and developmental disorders:Data from the 2016-2020 National Survey of Children's Health

Background:Adopting a healthy lifestyle during childhood could improve physical and mental health outcomes in adulthood and reduce relevant disease burdens.However,the lifestyles of children with mental,behavioral,and developmental disorders(MBDDs)remains under-described within the literature of public health field.This study aimed to examine adherence to 24-hour movement guidelines among children with MBDDs compared to population norms and whether these differences are affected by demographic characteristics.Methods:Data were from the 2016-2020 National Survey of Children’s Health—A national,population-based,cross-sectional study.We used the data of 119,406 children aged 6-17 years,which included 38,571 participants with at least 1 MBDD and 80,835 without.Adherence to the 24-hour movement guidelines was measured using parent-reported physical activity,screen time,and sleep duration.Results:Among children with MBDDs,20.3%,37.0%,60.7%,and 77.3%met the physical activity,screen time,sleep,and at least 1 of the 24-hour movement guidelines.These rates were lower than those in children without MBDDs(22.8%,46.2%,66.7%,and 83.4%,respectively;all p<0.001).Children with MBDDs were less likely to meet these guidelines(odds ratio(OR)=1.21,95%confidence interval(95%CI):1.13-1.30;OR=1.37,95%CI:1.29-1.45;OR=1.29,95%CI:1.21-1.37;OR=1.45,95%CI:1.35-1.56)than children without MBDDs.Children with emotional disorders had the highest odds of not meeting these guidelines(OR=1.43,95%CI:1.29-1.57;OR=1.48,95%CI:1.37-1.60;OR=1.49,95%CI:1.39-1.61;OR=1.72,95%CI:1.57-1.88)in comparison to children with other MBDDs.Among children aged12-17 years,the difference in proportion of meeting physical activity and screen time guidelines for children with vs.children without MBDD was larger than that among children aged 6-11 years.Furthermore,the above difference of meeting physical activity guidelines in ethnic minority children was smaller than that in white children.Conclusion:Children with MBDDs were less likely to meet individual or combined 24-hour movement guidelines than children without MBDDs.In educational and clinical settings,the primary focus should be on increasing physical activity and limiting screen time in children aged 12-17 years who have MBDDs;and specifically for white children who have MBDDs,increasing physical activity may help.

Arterial stiffness expressed as brachial–ankle pulse wave velocity and gait assessment independent of lower extremity strength:a cross-sectional study in the older men population

BACKGROUND Older men are more vulnerable to fatal falls than women,and gait disturbances contribute to the risk of falls.Studies have assessed the association between arterial stiffness and gait dysfunction,but the results have been inconclusive.This study aimed to conduct a cross-sectional analysis to evaluate the association between brachial–ankle pulse wave velocity(baPWV)and gait assessment in older men.METHODS Data from the 2014–2015 Korea Institute of Sport Science Fitness Standards project were used for the analysis.The inclusion criteria were men aged>65 years with gait assessment[the 30-s chair stand test(30s-CST),the timed up and go(TUG)test,the figure-of-8 walk(F8W)test,the 2-min step test(2MST),and the 6-min walk test(6MWT)]and baPWV measurement data.Generalized linear regression analysis was conducted with multiple confounding factor adjustments,including lower extremity isometric strength.RESULTS A total of 291 participants were included in the analysis.The mean age was 71.38±4.40 years.The mean values were as follows:(1)30s-CST,17.48±5.00;(2)TUG test,6.01±1.10 s;(3)F8W test,25.65±4.71 s;(4)2MST,102.40±18.83 per 2 min;and(5)6MWT,500.02±85.65 m.After multivariable adjustment,baPWV was associated with the 6MWT(β=−0.037,95%CI:−0.072–−0.002),TUG test(β=0,95%CI:0.000–0.001),and F8W test(β=0.002,95%CI:0.000–0.004).baPWV was not associated with the 30s-CST and 2MST.CONCLUSIONS The current study showed a statistically significant association between gait assessments and arterial stiffness,independent of lower extremity strength.However,this association was modest.Future prospective studies are needed to elucidate the complex relationship between arterial stiffness and gait dysfunction.

Foam rolling and stretching do not provide superior acute flexibility and stiffness improvements compared to any other warm-up intervention: A systematic review with meta-analysis

Background:Acute improvement in range of motion(ROM)is a widely reported effect of stretching and foam rolling,which is commonly explained by changes in pain threshold and/or musculotendinous stiffness.Interestingly,these effects were also reported in response to various other active and passive interventions that induce responses such as enhanced muscle temperature.Therefore,we hypothesized that acute ROM enhancements could be induced by a wide variety of interventions other than stretching or foam rolling that promote an increase in muscle temperature.Methods:After a systematic search in PubMed,Web of Science,and SPORTDiscus databases,38 studies comparing the effects of stretching and foam rolling with several other interventions on ROM and passive properties were included.These studies had 1134 participants in total,and the data analysis resulted in 140 effect sizes(ESs).ES calculations were performed using robust variance estimation model with R-package.Results:Study quality of the included studies was classified as fair(PEDro score=4.58)with low to moderate certainty of evidence.Results showed no significant differences in ROM(ES=0.01,p=0.88),stiffness(ES=0.09,p=0.67),or passive peak torque(ES=-0.30,p=0.14)between stretching or foam rolling and the other identified activities.Funnel plots revealed no publication bias.Conclusion:Based on current literature,our results challenge the established view on stretching and foam rolling as a recommended component of warm-up programs.The lack of significant difference between interventions suggests there is no need to emphasize stretching or foam rolling to induce acute ROM,passive peak torque increases,or stiffness reductions.

Key factors to prioritize when preparing for the Olympic Games

We need more research that will fulfill the needs of athletes and coaches.This is a common statement,highly relevant nowadays only a few weeks before the commencement of the Paris 2024 Olympic Games.To fill this gap,we have identified 6 topics that we feel coaches and athletes would be interested in learning more to optimize their preparation for the Olympics.These topics are.

Training muscles to keep the aging brain fit

1.Aging and exercise Aging is associated with the decline of cellular,tissue,and systemic functions and is characterized by at least 7 highly interdependent molecular pillars of aging1(Fig.1).Besides compromised genetic functions(telomer shortening and epigenetic dysregulation),metabolic efficiency(impaired mitochondrial functions and nutrient sensing),and cellular stress responses deteriorate.Consequential disruption of normal protein regulation(proteostasis)in combination with impaired cellular waste clearance leads to the accumulation of macromolecular damage(and in some cases to specific protein aggregation pathologies,like in Alzheimer’s dementia brains).

Reactive oxygen species promote endurance exercise-induced adaptations in skeletal muscles

The discovery that contracting skeletal muscle generates reactive oxygen species(ROS)was first reported over 40 years ago.The prevailing view in the 1980s was that exercise-induced ROS production promotes oxidation of proteins and lipids resulting in muscle damage.However,a paradigm shift occurred in the 1990s as growing research revealed that ROS are signaling molecules,capable of activating transcriptional activators/coactivators and promoting exercise-induced muscle adaptation.Growing evidence supports the notion that reduction-oxidation(redox)signaling pathways play an important role in the muscle remodeling that occurs in response to endurance exercise training.This review examines the specific role that redox signaling plays in this endurance exercise-induced skeletal muscle adaptation.We begin with a discussion of the primary sites of ROS production in contracting muscle fibers followed by a summary of the antioxidant enzymes involved in the regulation of ROS levels in the cell.We then discuss which redox-sensitive signaling pathways promote endurance exercise-induced muscle adaptation and debate the strength of the evidence supporting the notion that redox signaling plays an essential role in muscle adaptation to endurance exercise training.In hopes of stimulating future research,we highlight several important unanswered questions in this field.

Prevalence and correlates of meeting the muscle-strengthening exercise recommendations among Chinese children and adolescents:Results from 2019 Physical Activity and Fitness in China—The Youth Study

Purpose This study aimed to describe the national prevalence of Chinese children and adolescents who met the World Health Organization muscle-strengthening exercise(MSE)recommendations and identify correlates of meeting the MSE recommendations.Methods Cross-sectional data from the 2019 Physical Activity and Fitness in China—The Youth Study,a nationally representative sample of Chinese children and adolescents(n=80,413;mean age=13.7 years;53.9%girls)and their parents,were analyzed.Children and adolescents who reported engaging≥3 days(up to 7 days)of MSE per week were classified as meeting the MSE recommendations.MSE,demographics,lifestyle behaviors(sport participation,moderate-to-vigorous physical activity,screen time,and sleep duration),exercise intention,peer and parental support,and parental MSE participation were assessed through self-reports.Logistic regression models were used to determine the correlates of meeting the MSE recommendations.The analyses were completed in 2020.Results Overall,39.3%of children and adolescents met the MSE recommendations.Girls,10th-12th graders,minorities,those from lower income households and those from families with lower parental education were less likely to meet the MSE recommendations.Children and adolescents who were proficient in≥2 sports were more likely to meet the MSE recommendations(adjusted odds ratio(aOR)=1.44,95%confidence interval(95%CI):1.26-1.65),as were those with more moderate-to-vigorous physical activity(aOR=1.57,95%CI:1.53-1.61).Additionally,children and adolescents with high exercise intention(aOR=1.60,95%CI:1.51-1.69),those whose parents met the adult MSE recommendations(aOR=1.46,95%CI:1.40-1.52),and those who received high peer(aOR=1.27,95%CI:1.20-1.34)and parental support(aOR=1.07,95%CI:1.04-1.12)were more likely to meet the MSE recommendations.Conclusion Less than two-fifths of Chinese children and adolescents met the World Health Organization MSE recommendations.The correlates identified in our study can help inform the development of school and community based strategies and policies to enhance participation in MSE and improve muscular fitness of all Chinese children and adolescents.

The effects of 12 weeks of functional strength training on muscle strength,volume and activity upon exposure to elevated Gz forces in high-performance aircraft personnel

Background:Technological advancements in modern military and acrobatic jet planes have resulted in extraordinary psychophysiological loads being exerted upon flying personnel,including inducing neck and back pain.The purpose of this study was to examine the effects of 12 weeks of functional strength training on 1)the volume and strength of the neck and shoulder muscles and 2)muscular activity upon exposure to helmets of different masses and elevated Gz forces in a long-arm centrifuge in high-performance aircraft personnel.Methods:Eighteen participants underwent 12 weeks of functional strength training(n=12)or the control protocol(n=6)without additional strength training.Pre-and post-intervention tests included evaluations of isometric strength of the head extensor muscles,flexion,and lateral flexion and rotation,as well as magnetic resonance imaging(MRI)to measure the volume of the m.sternocleidomastoideus,m.trapezius,and deep neck muscles.Furthermore,during a long-arm centrifuge(+1.4 and+3Gz)protocol,the muscular activity levels of the m.sternocleidomastoideus,m.trapezius and m.erector spinae muscles were assessed without a flight helmet,with a helmet,and with a helmet and night vision goggles.Each participant’s perception of muscular strain was noted immediately after the long-arm centrifuge protocol.Results:The maximal isometric strength in all exercises and muscle volumes increased in the training group but not the control group(P<0.05).Relative muscle activity(%MVC)with a helmet decreased after the intervention in the training but not the control group(P=0.01).Relative muscle activity while wearing a helmet and night vision goggles was higher after intervention in the control group than in the training group(P<0.01).The perceived muscular strain of the neck muscles induced by the long-arm centrifuge did not differ between the groups.Conclusions:Twelve weeks of functional strength training improves the maximal isometric strength and volume of neck and shoulder muscles and leads to lower relative muscle activation upon exposure to elevated Gz forces in a long-arm centrifuge.

Preparation of Molecularly Imprinted Composites Initiated by Hemin/Graphene Hybrid Nanosheets and Its Application in Detection of Sulfamethoxazole

Molecularly imprinted polymers(MIPs)exhibit high selectivity resulting from imprinted cavities and superior performance from functional materials,which have attracted much attention in many fields.However,the combination of MIPs film and functional materials is a great challenge.In this study,hemin/graphene hybrid nanosheets(H-GNs)were used to initiate the imprinted polymerization by catalyzing the generation of free radicals.Thus,MIPs using sulfamethoxazole as the template was directly prepared on the surface of H-GNs without any film modification.Most importantly,the template could be absorbed on the H-GNs to enhance the number of imprinted sites per unit surface area,which could improve the selectivity of MIPs film.Thus,the composites could exhibit high adsorption capacity(29.4 mg/g),imprinting factor(4.2)and excellent conductivity,which were modified on the surface of electrode for rapid,selective and sensitive detection of sulfamethoxazole in food and serum samples.The linear range was changed from 5μg/kg to 1 mg/g and the limit of detection was 1.2μg/kg.This sensor was free from interference caused by analogues of sulfamethoxazole,which provides a novel insight for the preparation of MIPs-based sensor and its application in food safety monitoring and human exposure study.

The complex role of physical exercise and reactive oxygen species on brain

Reactive oxygen species （ROS） are continuously generated during aerobic metabolism and at moderate level. They play a role in redox signaling, but in significant concentration they cause oxidative damage and neurodegeneration. Because of the enhanced sensitivity of brain to ROS, it is especially important to maintain the normal redox state in different types of neuron cells. In last decade it became clear that regular exercise beneficially affects brain function, and can play an important preventive and therapeutic role in stroke, Alzheimer, and Parkinson diseases. The effects of exercise appear to be very complex and could include neurogenesis via neurotrophic factors, increased capillariszation, decreased oxidative damage, and increased proteolyfic degradation by proteasome and neprilysin. Data from our and other laboratories indicate that exercise-induced modulation of ROS levels plays a role in the protein content and expression of brain-derived neurotrophic factor, tyrosinerelated kinase B （TrkB）, and cAMP response element binding protein, resulting in better function and increased neurogenesis. Therefore, it appears that exercise-induced modulation of the redox state is an important means, by which exercise benefits brain function, increases the resistance against oxidative stress, facilitates recovery from oxidative stress, and attenuates age-associated decline in cognition.

MicroRNA expression profile and lipid metabolism characteristics in liver of rat undergoing high-fat diet

This study aimed to investigate the microRNA expression profile and the characteristics of lipid metabolism in the livers of rats undergoing a high-fat diet.Fifty male Sprague-Dawley(SD)rats were divided into a standard chow group(C group,N=10)and a high-fat diet group(H group,N=40).After 12 weeks,the rat body weight,body length,fat mass,and serum lipid concentration were measured.The expression profile of microRNAs and the gene and protein expression levels involved in lipid metabolism in rat liver were detected.Body fat and serum lipid concentrations were all significantly higher in the H group than those in the C group(p<0.05 or p<0.01).The expression of 10 microRNAs showed significant differences in the liver(p<0.05).In particular,the let-7 family expression levels significantly increased(p<0.05)in the H group compared with those in the C group.Compared with the C group,the high-fat diet resulted in low FAS,CPT1A,and ApoAI mRNA expression levels(p<0.05 or p<0.01)and high PPARαand FAT/CD36 mRNA expression levels in the H group rat liver(p<0.01).Meanwhile,the protein PPARα,FAS,CPT1A,FAT/CD36,and ApoAI expression levels were all significantly lower in the H group than those in the C group(p<0.05 or p<0.01).In conclusion,the high-fat diet increased the body fat and serum lipid levels and altered the 10 microRNA expression levels in the liver.The high-fat diet may affect hepatic carbohydrate metabolism and increase ectopic fat accumulation through let-7 family overexpression.The high-fat diet for 12 weeks decreased lipid metabolism level in the liver,thereby decreasing fatty acid synthesis,oxidation,and transport by down-regulating the PPARα,FAS,CPT1A,FAT/CD36,and ApoAI protein levels.

Relationship of proprioception,cutaneous sensitivity,and muscle strength with the balance control among older adults

Background:Balance impairment is one of the strongest risk factors for falls.Proprioception,cutaneous sensitivity,and muscle strength are 3 important contributors to balance control in older adults.The relationship that dynamic and static balance control has to proprioception,cutaneous sensitivity,and muscle strength is still unclear.This study was performed to investigate the relationship these contributors have to dynamic and static balance control.Methods:A total of 164 older adults(female=89,left dominant=15,age:73.5±7.8 years,height:161.6±7.1 cm,weight:63.7±8.9 kg,mean±SD)participated in this study.It tested the proprioception of their knee flexion/extension and ankle dorsi/plantarflexion,along with cutaneous sensitivity at the great toe,first and fifth metatarsals,arch,and heel,and the muscle strength of their ankle dorsi/plantarflexion and hip abduction.The Berg Balance Scale(BBS)and the root mean square(RMS)of the center of pressure(CoP)were collected as indications of dynamic and static balance control.A partial correlation was used to determine the relationship between the measured outcomes variables(BBS and CoPRMS)and the proprioception,cutaneous sensitivity,and muscle strength variables.Results:Proprioception of ankle plantarflexion(r=-0.306,p=0.002)and dorsiflexion(r=-0.217,p=0.030),and muscle strength of ankle plantarflexion(r=0.275,p=0.004),dorsiflexion(r=0.369,p<0.001),and hip abduction(r=0.342,p<0.001)were weakly to moderately correlated with BBS.Proprioception of ankle dorsiflexion(r=0.218,p=0.020)and cutaneous sensitivity at the great toe(r=0.231,p=0.041)and arch(r=0.285,p=0.002)were weakly correlated with CoP-RMS in the anteroposterior direction.Proprioception of ankle dorsiflexion(r=0.220,p=0.035),knee flexion(r=0.308,p=0.001)and extension(r=0.193,p=0.040),and cutaneous sensitivity at the arch(r=0.206,p=0.028)were weakly to moderately correlated with CoP-RMS in the mediolateral direction.Conclusion:There is a weak-to-moderate relationship between proprioception and dynamic and static balance control,a weak relationship between cutaneous sensitivity and static balance control,and a weak-to-moderate relationship between muscle strength and dynamic balance control.

The effects of exercise on self-rated sleep among adults with chronic sleep complaints

Purpose： The purpose of this study was to evaluate whether and to what extent the observed effects on self-rated sleep in a previous study using a combined treatment program with physical exercise and sleep education can be attributed by the physical activity （PA） component. Methods： The present study reports supplementary analysis of an already described and published study. Data were provided by a nonclinical sample of 98 normal-active adults with chronic initiating and the maintaining of sleep complaints. The additional analysis included sleep log, exercise log, and daily pedometer data which were collected during a baseline week and 6-week of a combined intervention. Results： The results indicate that the number of steps （p -- 0.02） and the duration of PA （p = 0.01） is significantly related to the improvement in subjective sleep measures and therefore reveal an independent effect within this combined sleep program. Sleep diary data （recuperation of sleep, number of awakenings after sleep onset, and wake time after sleep onset time） improved significant （all p 〈 0.01） over the intervention program. About 50% of the participants stated that the PA had an effect on their improvement. Conclusion： Improvements on subjective sleep quality after a combined intervention cannot be attributed to the cognitive component alone, but PA has an independent effect. Adults with chronic sleep complaints benefit from exercise. Therefore structured PA should be implemented in any sleep management programs.

The role of exercise in brain DNA damage

Cells are constantly subjected to cytotoxic and genotoxic insults resulting in the accumulation of unrepaired damaged DNA,which leads to neuronal death.In this way,DNA damage has been implicated in the pathogenesis of neurological disorders,cancer,and aging.Lifestyle factors,such as physical exercise,are neuroprotective and increase brain function by improving cognition,learning,and memory,in addition to regulating the cellular redox milieu.Several mechanisms are associated with the effects of exercise in the brain,such as reduced production of oxidants,up-regulation of antioxidant capacity,and a consequent decrease in nuclear DNA damage.Furthermore,physical exercise is a potential strategy for further DNA damage repair.However,the neuroplasticity molecules that respond to different aspects of physical exercise remain unknown.In this review,we discuss the influence of exercise on DNA damage and adjacent mechanisms in the brain.We discuss the results of several studies that focus on the effects of physical exercise on brain DNA damage.

Changes in Myofibrillar and Mitochondrial Compartments during Increased Activity: Dependance from Oxidative Capacity of Muscle

Striated muscle tissue contains fibers with high oxidative capacity (heart muscle), higher oxidative capacity (type I and IIA fibers of skeletal muscle) and low oxidative capacity (type IIB/X fibers of skeletal muscle). Muscle fibers with higher oxidative capacity contain large mitochondria tightly packed with cristae as well as small forms of mitochondria containing relatively few cristae. The intensive development of the mitochondrial apparatus in the post-activity period reflects the adaptive processes, which is intended to supply the increased energy requirements of muscle fibers with higher oxidative capacity. Muscle fibers with low oxidative capacity contain significantly less mitochondria than fibers with higher capacity. It is typical to type IIB fibers that after intensive muscle activity there are damaged myofibrils in a relatively small area, some myofibrils are twisted and lose the connection with the neighboring structures. It is still not fully known how skeletal muscles with different oxidative capacity respond to an increased functional activity and what differences exist in these fibers between oxidative capacity and function of myofibrils. The aim of the present short review was to compare structural-functional changes in mitochondrial and myofibrillar compartments of heart and skeletal muscle fibers with different oxidative capacity and the effect of increased functional activity on the interaction of these compartments.

About the structure of posturography: Sampling duration, parametrization, focus of attention (part II)

There exists a great variety of posturographic parameters which complicates the evaluation of center of pressure (COP) data. Hence, recommendations were given to use a set of complementary parameters to explain most of the variance. However, it is unknown whether a dual task paradigm leads to different parametrization sets. On account of this problem an exploratory factor analysis approach was conducted in a dual task experiment. 16 healthy subjects stood on a force plate performing a posture-cognition dual task (DT, focus of attention on a secondary task) with respect to different sampling durations. The subjects were not aware of being measured in contrast to a baseline task condition (BT, internal focus of attention) in the previously published part I. In compareson to BT a different factor loading pattern appears. In addition, factor loadings are strongly affected by different sampling durations. DT reveals a change of factor loading structure with longer sampling durations compared to BT. Specific recommendations concerning a framework of posturographic parametrization are given.