bluuebunny/crossref_metadata_2025 huggingface dataset:
Generation and propagation of bursts of activity in the developing basal ganglia
Authors: Klavinskis-Whiting Sebastian , Bitzenhofer Sebastian , Hanganu-Opatz Ileana , Ellender Tommas
Published: August 2023

The neonatal brain is characterized by intermittent bursts of oscillatory activity interspersed by relative silence. Although well-characterized for many cortical areas, to what extent these propagate and interact with subcortical brain areas is largely unknown. Here, early network activity was recorded from the developing basal ganglia, including motor/somatosensory cortex, dorsal striatum, and intralaminar thalamus, during the first postnatal weeks in mice. An unsupervised detection and classification method revealed two main classes of bursting activity, namely spindle bursts and nested gamma spindle bursts, characterized by oscillatory activity at ~ 10 and ~ 30 Hz frequencies, respectively. These were reliably identified across all three brain regions and exhibited region-specific differences in their structural, spectral, and developmental characteristics. Bursts of the same type often co-occurred in different brain regions and coherence and cross-correlation analyses reveal dynamic developmental changes in their interactions. The strongest interactions were seen for cortex and striatum, from the first postnatal week onwards, and cortex appeared to drive burst events in subcortical regions. Together, these results provide the first detailed description of early network activity within the developing basal ganglia and suggest that cortex is one of the main drivers of activity in downstream nuclei during this postnatal period.
IBD Camp Oasis: A look at Participants’ Social-Emotional Well-Being and Protective Factors During Camp and Beyond
Authors: Singh Namita , Steiner Steven J , Fauth Rebecca , Moosmann Danyel , Arnold Janis , Elkadri Abdul , Marinoni Daniel , Molloy Laurel , Johnson Rescola Becky , Tung Jeanne , Utterson Elizabeth C
Published: August 2023

Background

Camp Oasis is an annual week-long camp serving children with inflammatory bowel disease (IBD) and hosted by the Crohn’s and Colitis Foundation. Youth with IBD are at increased risk for mental health challenges, with Camp Oasis potentially mitigating these risks. The aim of this study is to measure change in and predictors of social-emotional well-being and protective factors of self-worth as a result of attending Camp Oasis.

Methods

Between 2012 and 2019, a voluntary survey was administered to participants and their caregivers to reflect on their perceptions of social/emotional well-being and protective factors related to chronic disease. T-tests compared change in participants’ and caregivers’ perceptions before and after camp; path analyses examined the key predictors of social-emotional well-being.

Results

A total of 6011 online surveys were analyzed. Participants and caregivers reported consistently positive perceptions of participants’ experiences during and after camp. Significant improvements in confidence, independence, activity, comfort around others, being more open about disease, and taking medication as expected were observed. Being new to Camp Oasis was one of the strongest predictors of both disease-related self-efficacy and social connections after camp.

Conclusions

The uniformly high rates of participants’ perceptions during camp suggest camp is a life-changing experience for youth with IBD, reduces disease-related stigma, and enhances confidence and social skills. Participants’ positive experiences appear to foster notable benefits after camp in terms of openness, their sense of belonging, connections, and confidence.
From Russia with fear: fear appeals and the patterns of cyber-enabled influence operations
Authors: Etudo Ugochukwu , Whyte Christopher , Yoon Victoria , Yaraghi Niam
Published: August 2023

Much research on influence operations (IO) and cyber-enabled influence operations (CEIO) rests on the assumption that state-backed digital interference attempts to generically produce sociopolitical division favorable to the perpetrator’s own interests. And yet, the empirical record of malicious IO during the 2010s show that social media manipulation and messaging takes a number of forms. In this article, we survey arguments regarding the targeting tactics and techniques associated with digital age IO and suggest that existing accounts tend to ignore the strategic context of foreign interference. We propose that state-sponsored IO are not unlike conventional political messaging campaigns in that they are an evolving flow of information rooted in several key objectives and assumptions. However, the strategic position of foreign actors as an outside force constrains opportunities for effective manipulation and forces certain operational constraints that shape practice. These outside actors, generally unable to create sensation from nothing without being unveiled, rely on domestic events tied to a broad macrosocial division (e.g. an act of race violence or protest activity) to create the conditions wherein social media manipulation can be leveraged to strategic gain. Once an event occurs, belligerents tailor steps being taken to embed themselves in relevant social networks with the goal of turning that influence toward some action. We illustrate and validate this framework using the content of the Russian Federation’s coordinated trolling campaign against the USA between 2015 and 2016. We deploy an empirical testing approach centered on fear appeals as a likely method for engaging foreign populations relative to some domestic triggering event and find support of our framework. Specifically, we show that while strong associations exist between Russian ad emissions on Facebook and societal unrest in the period, those relationships are not statistically causal. We find a temporal ordering of social media content that is highly suggestive of a fear appeals strategy responsive to macrosocial dividing events. Of unique interest, we also see that malware is targeted to social media populations at later stages of the fear appeal threat lifecycle, implying lessons for those specifically interested in the relationship between CEIO and disinformation tactics.
Physical activity in childhood and adolescence and future depressive symptoms: an 11-year prospective cohort study
Authors: Knowles Christopher , Paradis Kyle F , Breslin Gavin , Shannon Stephen , Carlin Angela
Published: August 2023

Background

Physical activity (PA) can reduce young peoples’ risk of depressive symptoms. Associations between PA and depressive symptoms are often investigated over timeframes spanning minutes to weeks. Less is known about whether childhood/adolescent PA can predict depressive symptoms in early adulthood.

Methods

Using a nationally representative sample from Ireland, latent growth mixture modelling was performed to investigate the extent to which different PA trajectories existed from ages 9–17, whether gender, weight status, and socio-economic deprivation at age 9, predicted PA trajectories from ages 9–17, and whether trajectory class membership predicted depressive symptoms at age 20.

Results

A 4-class solution was the best fit to the data (AIC = 52 175.69; BIC = 52 302.69; ssaBIC = 52 245.49; entropy = 1.00). Classes were labelled according to their baseline PA and slope of their trajectory: ‘High-Decreasers’; ‘Moderate-Decreasers’; ‘Moderate-Stable’; and ‘Low-Increasers’. A negative linear association existed between activity trajectory and the likelihood class members were female, overweight or socioeconomically deprived at age 9. The most active class (High-Decreasers) were significantly less likely to report depressive symptoms at age 20 than other classes.

Conclusions

Multiple PA trajectories exist throughout childhood and adolescence although differences in PA levels reduced over time. The most/least active children continued to be the most/least active throughout adolescence. Those most active were least at risk of depressive symptoms in early adulthood. Being female, overweight or experiencing deprivation at age 9 were all risk factors for inactivity throughout adolescence. Findings have implications for public health and PA promotion in young people.
Adolescent alcohol and cannabis use as risk factors for head trauma in the Northern Finland Birth Cohort study 1986
Authors: Koivisto Maarit K , Puljula Jussi , Levola Jonna M , Mustonen Antti , Miettunen Jouko , Alakokkare Anni-Emilia , Niemelä Solja
Published: August 2023

Background

The aim of this study was to assess the associations between cannabis use and frequency of alcohol intoxication in adolescence with the risk of traumatic brain injury and craniofacial fractures in early adulthood. Hypothesis was that using alcohol and cannabis in adolescence could increase the risk for head traumas.

Methods

Data from the Northern Finland Birth Cohort 1986 (n = 9432 individuals) were used to investigate the prospective association between the self-reported frequency of alcohol intoxication (n = 6472) and cannabis use (n = 6586) in mid-adolescence and register-based, head trauma diagnoses by ages 32–33 years. To test the robustness of these associations, the statistical models were adjusted for a range of other confounders such as illicit drug use, previous head trauma and self-reported mental health problems.

Results

In multivariate analyses, cannabis use was statistically significantly associated with a greater risk of traumatic brain injury among females [hazard ratio (HR) 1.9, 95% confidence interval (CI) 1.1–3.2, P = 0.024). Frequent alcohol intoxication was a statistically significant independent risk factor for both traumatic brain injury (HR 2.6, 95% CI 1.7–3.9, P < 0.001) and craniofacial fractures (HR 2.7, 95% CI 1.6–4.8, P < 0.001) among males.

Conclusions

Cannabis use in adolescence appears to associate independently with elevated risk for traumatic brain injury among females, and frequent alcohol intoxication in adolescence seems to associate with elevated risk of both traumatic brain injury and craniofacial fractures among males.
Impact of the association between education and obesity on diabetes-free life expectancy
Authors: Brønnum-Hansen Henrik , Davidsen Michael , Andersen Ingelise
Published: August 2023

Background

The purpose of the study was to quantify the association between body weight and health by estimating the expected lifetime with and without diabetes (diabetes-free life expectancy) at age 30 and 65. In addition, the diabetes-free life expectancy was stratified by educational level.

Methods

Life tables by sex, level of education and obese/not obese were constructed using nationwide register data and self-reported data on body weight and height and diabetes from the Danish National Health Survey in 2021. Diabetes-free life expectancies were estimated by Sullivan’s method.

Results

The difference in life expectancy between not obese 30-year-old men with a long and a short education was 5.7 years. For not obese women, the difference was 4.1 years. For obese men and women, the difference in life expectancy at age 30 was 7.0 and 5.2 years. Women could expect more years without and fewer years with diabetes than men regardless of body weight and educational level. Diabetes-free life expectancy differed by 6.9 years between not obese 30-year-old men with a short and a long education and by 7.7 years for obese men with a short and a long education. For women, the differences were 5.9 and 6.6 years.

Conclusion

The results demonstrate an association of obesity and educational level with life expectancy and diabetes-free life expectancy. There is a need for preventive efforts to reduce educational inequality in life expectancy and diabetes-free life expectancy. Structural intervention will particularly benefit overweight people with short education.
Female meiotic drive shapes the distribution of rare inversion polymorphisms in Drosophila melanogaster
Authors: Koury Spencer A
Published: August 2023

In all species, new chromosomal inversions are constantly being formed by spontaneous rearrangement and then stochastically eliminated from natural populations. In Drosophila, when new chromosomal inversions overlap with a preexisting inversion in the population, their rate of elimination becomes a function of the relative size, position, and linkage phase of the gene rearrangements. These altered dynamics result from complex meiotic behavior wherein overlapping inversions generate asymmetric dyads that cause both meiotic drive/drag and segmental aneuploidy. In this context, patterns in rare inversion polymorphisms of a natural population can be modeled from the fundamental genetic processes of forming asymmetric dyads via crossing-over in meiosis I and preferential segregation from asymmetric dyads in meiosis II. Here, a mathematical model of crossover-dependent female meiotic drive is developed and parameterized with published experimental data from Drosophila melanogaster laboratory constructs. This mechanism is demonstrated to favor smaller, distal inversions and accelerate the elimination of larger, proximal inversions. Simulated sampling experiments indicate that the paracentric inversions directly observed in natural population surveys of D. melanogaster are a biased subset that both maximizes meiotic drive and minimizes the frequency of lethal zygotes caused by this cytogenetic mechanism. Incorporating this form of selection into a population genetic model accurately predicts the shift in relative size, position, and linkage phase for rare inversions found in this species. The model and analysis presented here suggest that this weak form of female meiotic drive is an important process influencing the genomic distribution of rare inversion polymorphisms.
Massachusetts’ innovative policy approach to expanding contraceptive options in primary care
Authors: Ciccariello Chloe , Prakash-Zawisza Viveka R , Pace Lydia E
Published: August 2023

As health systems pivot toward value-based care and as the reversal of Roe vs Wade has significantly decreased access to abortion care in the United States, contraception is increasingly recognized as a high-value health service. However, the United States has a long and troubling history of using contraceptive policies and practices, including forced sterilization, to limit the reproductive rights of people of color and individuals with disabilities. We hope to highlight an innovative program developed by Massachusetts’ Medicaid program, which seeks to expand access to long-acting reversible contraception (LARC) within primary care clinics in a way that promotes both value and reproductive justice. This program provides financial incentives for clinics that serve patients with Medicaid to offer LARC to all patients within the primary care space. Unlike LARC programs that exclusively target patients with Medicaid insurance and provide incentivizes based on number of LARC insertions, this policy has the potential to “lift all boats” and expand access to LARC for all patients regardless of payer. Careful evaluation of this program will be necessary to ensure that the intended outcomes—to increase access to LARC, promote reproductive justice, and deliver value to the health system—are achieved.
Institutions that define the policymaking role of courts: A comparative analysis of the supreme courts of Scandinavia
Authors: Ghavanini Anna Wallerman , Grendstad Gunnar , Schaffer Johan Karlsson
Published: August 2023

Scandinavian supreme courts have been described as deferential to the elected branches of government and reluctant to exercise their limited review powers. However, in recent years, these courts have increasingly decided cases impacting public policy making. Yet we lack comprehensive, comparative knowledge about the legal rules and judicial practices that govern the policymaking role of courts in Denmark, Norway, and Sweden. Addressing this gap, this article develops an analytical framework and systematically compares the evolving laws, rules, and practices that regulate the supreme courts’ constitutional review powers and court administration, the appointment and tenure of judges, access to the supreme courts, and their decision-making procedures over the last fifty years. The comparison reveals notable institutional differences across these judiciaries and finds that judicial expansion in Scandinavia has coincided with institutional changes that enhance judicial autonomy. This suggests that consequential reforms of domestic origin may have played a larger part in this development than previously appreciated.
Full Double Hölder Regularity of the Pressure in Bounded Domains
Authors: De Rosa Luigi , Latocca Mickaël , Stefani Giorgio
Published: August 2023

We consider Hölder continuous weak solutions $u\in C^{\gamma }(\Omega )$, $u\cdot n|_{\partial \Omega }=0$, of the incompressible Euler equations on a bounded and simply connected domain $\Omega \subset{\mathbb{R}}^{d}$. If $\Omega $ is of class $C^{2,1}$ then the corresponding pressure satisfies $p\in C^{2\gamma }_{*}(\Omega )$ in the case $\gamma \in (0,\frac{1}{2}]$, where $C^{2\gamma }_{*}$ is the Hölder–Zygmund space, which coincides with the usual Hölder space for $\gamma <\frac 12$. This result, together with our previous one in [ 11] covering the case $\gamma \in (\frac 12,1)$, yields the full double regularity of the pressure on bounded and sufficiently regular domains. The interior regularity comes from the corresponding $C^{2\gamma }_{*}$ estimate for the pressure on the whole space ${\mathbb{R}}^{d}$, which in particular extends and improves the known double regularity results (in the absence of a boundary) in the borderline case $\gamma =\frac{1}{2}$. The boundary regularity features the use of local normal geodesic coordinates, pseudodifferential calculus and a fine Littlewood–Paley analysis of the modified equation in the new coordinate system. We also discuss the relation between different notions of weak solutions, a step that plays a major role in our approach.
Some Cases of the Zilber–Pink Conjecture for Curves in 𝒜g
Authors: Papas Georgios
Published: August 2023

Following our work in [ 30], we extend the height bounds established by Y. André in his seminal research monograph [ 1] for $1$-parameter families of abelian varieties defined over number fields. In our exposition, we no longer assume that the family acquires completely multiplicative reduction at some point, as in André’s original result. As a corollary of these height bounds, we obtain unconditional results of Zilber–Pink-type for curves in $\mathcal{A}_{g}$, building upon recent results of C. Daw and M. Orr.
Asymptotic Betti Numbers for Hard Squares in the Homological Liquid Regime
Authors: Alpert Hannah , Kahle Matthew , MacPherson Robert
Published: August 2023

We study configuration spaces $C(n; p, q)$ of $n$ ordered unit squares in a $p$ by $q$ rectangle. Our goal is to estimate the $j$th Betti number for large $n$, $j$, $p$, and $q$. We consider sequences of area-normalized coordinates, where $\left (\frac {n}{pq}, \frac {j}{pq}\right )$ converges as $n$, $j$, $p$, and $q$ approach infinity. For every sequence that converges to a point in the “feasible region” in the $(x,y)$-plane identified in [3], we show that the factorial growth rate of the Betti numbers is the same as the factorial growth rate of $n!$. This implies that (1) the Betti numbers are vastly larger than for the configuration space of $n$ ordered points in the plane, which have the factorial growth rate of $j!$, and (2) every point in the feasible region is eventually in the homological liquid regime.
The suitability of UMLS and SNOMED-CT for encoding outcome concepts
Authors: Newbury Abigail , Liu Hao , Idnay Betina , Weng Chunhua
Published: August 2023

Objective

Outcomes are important clinical study information. Despite progress in automated extraction of PICO (Population, Intervention, Comparison, and Outcome) entities from PubMed, rarely are these entities encoded by standard terminology to achieve semantic interoperability. This study aims to evaluate the suitability of the Unified Medical Language System (UMLS) and SNOMED-CT in encoding outcome concepts in randomized controlled trial (RCT) abstracts.

Materials and Methods

We iteratively developed and validated an outcome annotation guideline and manually annotated clinically significant outcome entities in the Results and Conclusions sections of 500 randomly selected RCT abstracts on PubMed. The extracted outcomes were fully, partially, or not mapped to the UMLS via MetaMap based on established heuristics. Manual UMLS browser search was performed for select unmapped outcome entities to further differentiate between UMLS and MetaMap errors.

Results

Only 44% of 2617 outcome concepts were fully covered in the UMLS, among which 67% were complex concepts that required the combination of 2 or more UMLS concepts to represent them. SNOMED-CT was present as a source in 61% of the fully mapped outcomes.

Discussion

Domains such as Metabolism and Nutrition, and Infections and Infectious Diseases need expanded outcome concept coverage in the UMLS and MetaMap. Future work is warranted to similarly assess the terminology coverage for P, I, C entities.

Conclusion

Computational representation of clinical outcomes is important for clinical evidence extraction and appraisal and yet faces challenges from the inherent complexity and lack of coverage of these concepts in UMLS and SNOMED-CT, as demonstrated in this study.
Social play predicts caution in juvenile Belding’s ground squirrels (Urocitellus beldingi)
Authors: Shehan Madelene I , Hernandez Melissa , Rodriguez Jenevieve D , Nunes Scott
Published: August 2023

Play is an important component of development in a range of mammalian species, and may provide adaptive benefits for young individuals in some cases. We evaluated the hypothesis that social play in juvenile Belding’s ground squirrels (Urocitellus beldingi) promotes development of cautious responses when individuals are confronted with a potential threat. We observed the play behavior of juvenile U. beldingi across the developmental period in which play primarily occurs. To measure caution, we conducted behavioral tests on individual squirrels at the beginning and toward the end of the play period, and again when the individuals were yearlings. During tests we recorded the distances at which squirrels first noticed and fled from a human intruder. In initial tests, juveniles with yearling mothers responded to intruders at greater distances than did juveniles with older mothers suggesting maternal effects on the development of caution. Distances at which juveniles noticed and fled from an intruder increased across the play interval, suggesting increased caution to a potential threat as early development progresses. Social play was a reliable predictor of increases in caution, with juveniles who engaged in social play at higher rates having greater increases in the distance to notice and flee from an intruder. Distances to flee from an intruder at the end of the play interval were reliable predictors of distances to flee from an intruder as a yearling, suggesting consistency in cautious responses among individual U. beldingi over time. Rates of social play as a juvenile were reliable predictors of distances to notice and flee from an intruder as a yearling, suggesting that possible influences of play behavior on cautious responses extend beyond the juvenile period.
Bacterial communities and prevalence of antibiotic resistance genes carried within house flies (Diptera: Muscidae) associated with beef and dairy cattle farms
Authors: Neupane Saraswoti , Talley Justin L , Taylor David B , Nayduch Dana
Published: August 2023

House flies (Musca domestica Linnaeus) are vectors of human and animal pathogens at livestock operations. Microbial communities in flies are acquired from, and correlate with, their local environment. However, variation among microbial communities carried by flies from farms in different geographical areas is not well understood. We characterized bacterial communities of female house flies collected from beef and dairy farms in Oklahoma, Kansas, and Nebraska using 16S rDNA amplicon sequencing and PCR. Bacterial community composition in house flies was affected by farm type and location. While the shared number of taxa between flies from beef or dairy farms was low, those taxa accounted >97% of the total bacterial community abundance. Bacterial species richness was 4% greater in flies collected from beef than in those collected from dairy farms and varied by farm type within states. Several potential pathogenic taxa were highly prevalent, comprising a core bacterial community in house flies from cattle farms. Prevalence of the pathogens Moraxella bovis and Moraxella bovoculi was greater in flies from beef farms relative to those collected on dairy cattle farms. House flies also carried bacteria with multiple tetracycline and florfenicol resistance genes. This study suggests that the house flies are significant reservoirs and disseminators of microbial threats to human and cattle health.
On abnormal Phlebotomus perniciosus (Diptera: Psychodidae: Phlebotominae) from the center of Tunisia
Authors: Remadi Latifa , Chargui Najla , Depaquit Jérôme , Randrianambinintsoa Fano José , Chaâbane-Banaoues Raja , Babba Hamouda , Haouas Najoua
Published: August 2023

Phlebotomus perniciosus is the most important vector of Leishmania infantum in the Western part of the Mediterranean basin. Atypical specimens of Ph. perniciosus called (pna) with a parameral sheath simply curved, not bifurcated, have been reported in many locations. In this study, we describe abnormal Ph. perniciosus male specimens. Sand flies were collected in center Tunisia and identified morphologically. Cytochrome b PCR-sequencing was carried out for abnormal Ph. perniciosus male specimens in order to confirm the morphological identification and assess the intraspecific genetic polymorphism. Abnormal Ph. perniciosus specimens were characterized by a multifurcated parameral sheath. A parsimonious haplotype network based on cyt b locus analysis showed that typical and abnormal Ph. perniciosus described in our investigation were grouped together in the same branch. Thus, genetic outcomes confirmed that the new phenotype is only an original morphotype of Ph. perniciosus.
Contrast mechanism at landing energy near 0 eV in super low-energy scanning electron microscopy
Authors: Aoyama Tomohiro , Mikmeková Šárka , Kumagai Kazuhiro
Published: August 2023

In recent years, the technique of scanning electron microscopy (SEM) observation with low landing energy of a few keV or less has become common. We have especially focused on the drastic contrast change at near 0 eV. Using a patterned sample consisting of Si, Ni and Pt, threshold energies where the total reflection of incident electrons occurs were investigated by SEM at near 0 eV. In both the cases of in-situ and ex-situ sample cleaning, drastic changes in the brightness of each material were observed at near 0 eV, with threshold energies in the order Si < Ni < Pt. This order agreed with the order of the literature values of the work functions and the surface potentials measured by Kelvin force probe microscopy. This result suggests that the difference of the threshold energy is caused by the difference in surface potential due to the work function difference of each material. Although the order of the threshold energies also agreed with those of work functions reported in the literature, the work functions of air-exposed surfaces should be rather considered as ‘modified work functions’, since they could be significantly altered by the adsorbates, etc. Nevertheless, the difference of the threshold energy for each material was observed with commercial SEM at landing energy near 0 eV, which opens a new possibility to distinguish materials, although the difference should be rather recognized as ‘fingerprints’, since surface potentials are sensitive to conditions of surface treatments and atmospheric exposure.
Unpaid Debts to London Booksellers: John Harrison the Elder’s Lawsuit against Two Chapmen in 1585
Authors: McGovern Jonathan
Published: August 2023

This article presents a transcript of a recently discovered booklist from a 1585 lawsuit at the Court of Common Pleas. This list describes a large book sale made on 3 May 1584 to two chapmen named John Herne and Thomas Jackson. It throws light on the Elizabethan book trade and the litigation practices of London booksellers, and it contains rare evidence on the trade prices of early modern books. It also records the earliest known purchase of Edmund Spenser’s celebrated Shepheardes calender (first published in 1579).
Resisting the inevitable: human rights and the data society
Authors: Dao André
Published: August 2023

This article outlines a methodology for describing the encounter between human rights and digital data technologies. The methodology is orientated around a set of traditions within law and humanities scholarship—in particular, thinking critically and co-productively about human rights, as well as a concern with the plurality of law, and forms of authority. The aim of the methodology is to resist digital and human rights fatalism. It does so by producing descriptions that offer resources towards a better understanding of how certain visions of the future succeed, and how failed visions might be rearticulated.
Developmental biodynamics: the development of coordination
Authors: Watkins James
Published: August 2023

Motor development in humans has been viewed historically from two viewpoints, the neuromaturation perspective and the information-processing perspective. However, these approaches fail to account for the great flexibility demonstrated by individuals in accommodating rapidly changing task demands. The purpose of this chapter is to describe the increasingly widely held dynamical systems view of motor development. From a dynamical systems perspective, coordinated movement emerges from the intrinsic self-organising properties of the dynamical system consisting of the individual, the task, and the environment. The actual pattern of movement that emerges depends upon the state of the system components which impose constraints on the types of movement that may emerge; the constraints arise from the anthropometry and physical ability of the individual (individual constraints), the requirements of the task (task constraints), and the prevailing environmental conditions (environmental constraints). Each type of constraint influences the movement pattern that emerges by encouraging certain types of movement and discouraging others. Abnormal movement due to cerebral palsy, disease, or injury is likely to be due to abnormal individual constraints in the form of abnormal energy sources. Therapy directed at normalising the abnormal energy sources is likely to be more effective than therapy directed at normalising the abnormal kinematics.
Molecular exercise physiology
Authors: Meinhold Marius , Wackerhage Henning
Published: August 2023

Molecular exercise physiology is the study of exercise physiology using molecular biology methods. The development of differentiated cell types is regulated by transcription factors such as the muscle-making MyoD that can specify the cell type of a cell. Similar transcription factors regulate the development of muscle, tendons, and bones. Maternal nutrition and exercise affect development of the embryo and this is commonly through epigenetic mechanisms. Adaptation to exercise is a consequence of signal transduction which involves i) the sensing of exercise-related signals such as calcium, mechanical stress, or hormones by sensor proteins; ii) the convection, amplification, and computation of such signals by signalling proteins and networks; and iii) the regulation of the actual adaptations through gene expression, protein breakdown, or cell death by effector proteins. Many sport- and exercise-related traits as well as development and body height depend on both common and rare DNA sequence variations. Examples for rare DNA sequence variations with a large effect on a sport- and exercise-related trait are the muscle mass-increasing myostatin (GDF8) loss-of-function and the haematocrit-increasing erythropoietin receptor (EPOR) gain-of-function mutations. In addition, hundreds to thousands of common DNA sequence variations contribute to the inherited variability of development, body height, strength, and endurance. Finally, current genetic performance tests are not meaningful as they only explain a fraction of the variation of sport- and exercise-related traits and there are ethical concerns.
Exercise and physiological variability: analysis and applications
Authors: Biltz George R , Lundstrom Christopher J
Published: August 2023

Physiological time series data for heart rate, respiratory rate, and gait all reveal sequential variability that is neither totally random nor completely regular. This irregular variability, observed across spatial and temporal scales, is an inherent feature of biological systems and physiological functions and can be distinguished as bounded variability. Exercise science traditionally reports the mean and standard deviation for a data set. However, these linear statistics do not recognise the interdependent and iterated physiological relationships that generate the temporal data sequence. In a complex systems approach, the time series data contain embedded information about the dynamics of the physiological processes that generated them. Variability analysis offers multiple methods to investigate scaling, power law, and fractal-like features in time series data. Complex systems and variability analysis characterise how physiological systems adapt to changes in their internal or external environments. Exercise and physical activity are opportunities to explore physiological variability and adaptability. Adaptability balances the more familiar principle of homeostatic stability and enhances understanding of the complexity of the response to exercise. The assessment of intra-individual physiological variability and adaptability allows insight into the heterogeneity of the exercise response and helps interpret interindividual differences. Variability analysis can be applied to time series data routinely collected during aerobic exercise testing. Wearable technology and analytics extend data collection and interpretation beyond the laboratory. Physiological variability analysis has the potential to individualise and improve physical activity interventions, training recommendations, and therapeutic exercise.
Cardiopulmonary responses to exercise
Authors: Armstrong Neil , McManus Ali M
Published: August 2023

During exercise, children and adolescents adopt a different breathing pattern and hyperventilate for a given metabolic demand compared to adults. The ventilatory threshold occurs at a higher percentage of peak oxygen uptake (V.O2peak) and the phase I delay and phase II ventilation time constant at the onset of exercise increase with age. After a rapid rise at the onset of exercise, stroke volume (SV) stabilises at ~50–60% V.O2peak. A continuing increase in heart rate (HR) is responsible for further increases in cardiac output (Q.) which rises in a curvilinear manner, with diminishing circulatory efficiency at near V.O2peak compensated for by an increase in arteriovenous oxygen content difference. Multiplicative allometric modelling of data has confirmed the importance of analysing sex-specific, concurrent changes in age-, growth-, and maturation-driven covariates when exploring the development of cardiopulmonary data. In all cases with age and fat-free mass (FFM) controlled for, maturity status does not make a significant, independent contribution to explaining the development of peak/maximum cardiopulmonary variables. Peak breathing frequency and HRmax are largely independent of sex, age, growth, maturity status, and V.O2peak. Pulmonary ventilation does not appear to limit the V.O2peak of healthy youth but even with FFM controlled for, SVmax or Q.max make an independent, significant contribution to explaining the development of cardiopulmonary fitness. Further longitudinal studies covering the prepubertal, pubertal, and postpubertal years and incorporating multiple covariates are necessary to elucidate fully the development of maximum cardiopulmonary variables and cardiopulmonary fitness.
Neuromuscular fatigue
Authors: Ratel Sébastien , Patikas Dimitrios A
Published: August 2023

Scientific evidence suggests that prepubertal children fatigue less than adults when performing whole-body dynamic activities, such as maximal cycling and short running bouts or maximal voluntary isometric and isokinetic muscle contractions. Although the mechanisms underpinning differences in fatigue between children and adults are not all fully understood, there is a consensus that children experience less peripheral fatigue (i.e. muscular fatigue) than their older counterparts. Central factors may also account for the lower fatiguability in children. Some studies have reported a higher reduction of muscle voluntary activation during fatiguing exercise in prepubertal children compared to adults. This could reflect a strategy of the central nervous system aimed at limiting the recruitment of motor units, in order to prevent any extensive peripheral fatigue. However, further studies are required to clarify this assumption.
Effort perception
Authors: Lamb Kevin L , Parfitt Gaynor , Eston Roger G
Published: August 2023

Research addressing children’s perceptions of exercise effort (their ‘perceived exertion’) has appeared steadily in the scientific literature over the last 44 years. Accepting that the established Borg adult rating of perceived exertion (RPE) scale was not appropriate for children, investigators set about developing child-specific scales which employed numbers, words, and/or images that were more familiar and understandable. Numerous studies have examined the validity and reliability of scales such as the CERT, PCERT, and OMNI among children aged 5–16 years, across different modes of exercise (cycling, running, stepping, resistance exercise), protocols (intermittent vs continuous, incremental vs non-incremental), and paradigms (estimation vs production). Such laboratory-based research has enabled the general conclusion that children can, especially with practice, use effort perception scales to differentiate between exercise intensity levels, and to self-regulate their exercise output to match various levels indicated on them. However, inconsistencies in the methodological approaches adopted diminish the certainty of some of the interpretations made by researchers. In addition, though often mentioned, the would-be application of effort perception in physical education and activity/health promotion contexts has been relatively ignored. Accordingly, the scope for research in this applied domain remains considerable.
Sedentary behaviour and health
Authors: Pearson Natalie , Sherar Lauren B
Published: August 2023

Changes in environments, modes of transportation, and the pervasiveness of screen-based technology have significantly reduced the demands and opportunities for physical activity and increased the opportunities for time spent sitting. Children in high- and middle-income countries spend around half of their waking hours sitting, with sitting for screen time being the most prevalent leisure-time sedentary behaviour among these populations. While sedentary behaviour research is still in its relative infancy, there is increasing evidence that sedentary behaviours, and particularly screen-based sedentary behaviours, have deleterious effects on the physiological and psychological health of children and young people. Measuring sedentary behaviours is challenging because of the need to accurately assess volume (e.g. min·day−1), multiple domains of behaviour (i.e. sitting in the classroom vs screen time), and the posture of behaviours. There is a clear need to reduce the time that children and adolescents spend sitting, and given that sedentary behaviours are complex, there are many unique correlates and determinants that are behaviour and context specific. Interventions targeting reductions in screen time have typically been school- based and shown small effects. More recently, interventions have targeted sitting time in the classroom utilising sit-to-stand desks, active breaks, and lessons and these are showing some promise. Further work is required in currently under-represented groups, including those from low- to middle-income countries that are experiencing rapid economic transition as well as often-overlooked groups that have unique needs and challenges that may impact sedentary behaviours, such as children with learning difficulties and long-term health conditions.
Physical activity, exercise, and cardiovascular health
Authors: Ferreira Isabel , Gill Jason MR
Published: August 2023

Cardiovascular disease (CVD) is partly a paediatric problem, as its onset extends back to childhood, even though clinical symptoms may not become apparent until much later in life. Therefore, from a primary prevention point of view, the extent to which physical activity or cardiorespiratory fitness (CRF) at a young age may deter the early stages of the CVD process is of utmost importance. Although there are no studies thus far that have linked, prospectively, objectively measured physical activity during youth to the incidence of CVD later in life, available evidence suggests that youthful physical activity may confer protection if sustained throughout the life-course. There is also evidence (mainly in men) linking CRF in late adolescence to incidence of CVD. The beneficial impacts physical activity and CRF seem to have on other cardiometabolic risk factors during youth, such as adiposity, blood pressure, dyslipidaemia, insulin resistance, and their clustering may constitute pathways through which they will prevent adverse outcomes later in life. However, the evidence available thus far remains unclear, due to insufficient dissection of the confounding and/or mediating effects of adiposity in these associations. There is also no evidence to support the view that physical activity and/or CRF affects pre-clinical signs of arterial damage in youth. Unfortunately, this field of research has been populated by poor methodology and research practices that require in-depth attention. Still, by affecting the intermediary pathways, lifelong physical activity, particularly of higher intensities, may also deter the age-related decrease in CRF and related signs of premature arterial ageing.
Physical activity, exercise, and eating and weight disorders
Authors: Hills Andrew P , Street Steven J , Byrne Nuala M
Published: August 2023

Eating disorders are complex and multifactorial clinical conditions characterised by a negative self-evaluative style and a focus on body shape and weight. The prevalence of disturbed eating behaviour that falls short of the clinical threshold for diagnosis as illness is higher than frank eating disorders such as anorexia nervosa, bulimia nervosa, and binge eating disorder. Disturbed eating behaviours and frank eating disorders impact a significant proportion of the population and are more common in adolescent girls and young women. Although eating behaviour is a fundamental component of eating disorders, the limited consideration of other important factors, such as physical activity, point to a gap in the theoretical understanding of both aetiology and treatment options. Given the importance to general health and well-being and covariance with eating disorder symptomatology, the limited consideration of physical activity in theoretical frameworks, diagnostic schemes, and treatment paradigms is surprising. Current evidence suggests that treatment approaches to eating disorders should attempt to minimise physical activity in anorexia nervosa and bulimia nervosa and increase it in binge eating disorder. Further research is needed to better understand if, and if so how, physical activity might be incorporated as therapy for individuals with disturbed eating behaviours or eating disorders.
Physical activity, exercise, and diabetes mellitus
Authors: Turner Lauren , van Mil Edgar GAH , Riddell Michael C
Published: August 2023

Regular physical activity and exercise improve cardiorespiratory fitness, body composition, skeletal muscle strength, and insulin sensitivity and lower the risk of premature all-cause mortality in children and adolescents with type 1 diabetes (T1D). However, exercise in individuals with T1D is complex, and the type, time, intensity, and duration of the activity will all influence a patient’s glycaemic response. Careful monitoring of blood glucose before, during, and following exercise can help patients make informed treatment decisions. Based on the glycaemic response to exercise, children, and adolescents with T1D can implement feeding or insulin strategies to help maintain euglycaemia.
Physical activity, exercise, and mental health
Authors: Cadenas-Sanchez Cristina , Torres-Lopez Lucia V , Migueles Jairo H
Published: August 2023

This chapter provides an extensive description of the associations of physical activity and physical fitness with mental health outcomes in youths. Both physical activity and physical fitness have been considered relevant markers of physical health outcomes in children in the last decades. This chapter discusses whether they can also be considered markers of mental health in this population. Although most of the evidence thus far is observational, experimental studies have been conducted in recent years to investigate the cause–effect relation between physical activity and mental health in children. In summary, small- and medium-sized associations have been extensively confirmed in observational studies, while several experimental studies point to a small, yet positive, effect on mental health outcomes in children and adolescents. These associations include numerous psychological well-being and ill-being indicators. As such, these constructs could also be considered markers of mental health in youth. In addition, this chapter also discusses the potential mechanisms that may explain such beneficial effects, including neurobiological, psychosocial, and behavioural factors. All the available evidence and this mechanistic view are considered to propose some practicalities to guide teachers and professionals in the development of physical activity programmes to maximise the effects on mental health outcomes in children. The recommendations, based on the available evidence, include aspects such as the intensity of the physical activity, the duration of the sessions and programmes, and the context for the delivery to preserve a sound mind in children.
Bio-banding in youth sport
Authors: Malina Robert M , Cumming Sean P , Coelho-e-Silva Manuel J
Published: August 2023

Bio-banding refers to grouping youth athletes within a given chronological age range into specific maturity groups based on predicted maturity status. Percentage of predicted adult height at the time of observation is the commonly used indicator of maturity status. Bio-banding is to some extent a modification of the concept of maturity-matching. Most applications to date have been limited to football. Bio-banded formats appear to change the constraints of the game and offer new challenges and learning opportunities for early- and late-maturing athletes. Bio-banding also appears to have benefits for the grouping and conditioning of athletes during the interval of the adolescent growth spurt, specifically optimising training effects and mitigating injury risk. Both youth and their coaches have responded favourably to bio-banded football tournaments and to training in bio-banded groups. Further research is required to validate, better understand, and refine the practice of bio-banding. Studies need to be extended beyond football among boys, specifically to football among girls and to athletes of both sexes in other sports.