4,700 research outputs found
A Spark Of Emotion: The Impact of Electrical Facial Muscle Activation on Emotional State and Affective Processing
Facial feedback, which involves the brain receiving information about the activation of facial muscles, has the potential to influence our emotional states and judgments. The extent to which this applies is still a matter of debate, particularly considering a failed replication of a seminal study. One factor contributing to the lack of replication in facial feedback effects may be the imprecise manipulation of facial muscle activity in terms of both degree and timing. To overcome these limitations, this thesis proposes a non-invasive method for inducing precise facial muscle contractions, called facial neuromuscular electrical stimulation (fNMES). I begin by presenting a systematic literature review that lays the groundwork for standardising the use of fNMES in psychological research, by evaluating its application in existing studies. This review highlights two issues, the lack of use of fNMES in psychology research and the lack of parameter reporting. I provide practical recommendations for researchers interested in implementing fNMES. Subsequently, I conducted an online experiment to investigate participants' willingness to participate in fNMES research. This experiment revealed that concerns over potential burns and involuntary muscle movements are significant deterrents to participation. Understanding these anxieties is critical for participant management and expectation setting. Subsequently, two laboratory studies are presented that investigated the facial FFH using fNMES. The first study showed that feelings of happiness and sadness, and changes in peripheral physiology, can be induced by stimulating corresponding facial muscles with 5âseconds of fNMES. The second experiment showed that fNMES-induced smiling alters the perception of ambiguous facial emotions, creating a bias towards happiness, and alters neural correlates of face processing, as measured with event-related potentials (ERPs). In summary, the thesis presents promising results for testing the facial feedback hypothesis with fNMES and provides practical guidelines and recommendations for researchers interested in using fNMES for psychological research
Adaptations in physiological and neuronal function during diet-induced obesity
Obesity significantly increases the risk of developing chronic conditions including type II diabetes, cardiovascular disease, and some cancers. The rate of obesity has tripled globally since 1975, which is in part due to the sudden prevalence and overconsumption of palatable high-fat diets (HFDs). Obesity profoundly perturbs the neural control of energy balance, affecting diverse cell types within the hypothalamus. However, an incomplete understanding of how HFD impacts the regulation of energy balance hinders our ability to more effectively treat obesity.
In this thesis, I describe the physiological and neuronal response to HFD feeding in rodents. We identified that HFD exposure elevates the body weight set point, which is initially driven by a transient hyperphagia. This hyperphagia coincides with increased excitatory transmission to lateral hypothalamic orexin (ORX) neurons, which regulate acute food intake. This suggests that ORX neurons may be involved in the initial hyperphagia, implicating them in the development of obesity. As HFD prolongs, body weight gain slows and reaches a new steady state regardless of age at the start, duration of feeding, or palatability of the diet. This sustained weight coincides with increased synaptic contacts to melanin-concentrating hormone (MCH) neurons, which promote weight gain and food intake, likely contributing to the maintenance of obesity.
The molecular mechanism underlying the establishment of a new set point remains elusive. During HFD feeding, the presence of a chronic low-grade
hypothalamic inflammation exacerbates weight gain, therefore we reasoned that inflammatory factors could modulate appetite-promoting neurons to maintain a new set point. We found that the inflammatory mediator prostaglandin E2 (PGE2) activate MCH neurons via its EP2 receptor (EP2R). Suppressing PGE2-EP2R on MCH neurons partially protects against excess weight gain and fat accumulation in the liver during HFD feeding. This mechanism could contribute to the maintenance of an elevated body weight set point in during diet-induced obesity.
Without long-term treatment options in face of the increasing rates of obesity, we are in desperate need of novel interventions. In the future, we hope that targeting EP2R on MCH neurons can lower body weight set point and aid in combatting obesity
Beam scanning by liquid-crystal biasing in a modified SIW structure
A fixed-frequency beam-scanning 1D antenna based on Liquid Crystals (LCs) is designed for application in 2D scanning with lateral alignment. The 2D array environment imposes full decoupling of adjacent 1D antennas, which often conflicts with the LC requirement of DC biasing: the proposed design accommodates both. The LC medium is placed inside a Substrate Integrated Waveguide (SIW) modified to work as a Groove Gap Waveguide, with radiating slots etched on the upper broad wall, that radiates as a Leaky-Wave Antenna (LWA). This allows effective application of the DC bias voltage needed for tuning the LCs. At the same time, the RF field remains laterally confined, enabling the possibility to lay several antennas in parallel and achieve 2D beam scanning. The design is validated by simulation employing the actual properties of a commercial LC medium
Blending the Material and Digital World for Hybrid Interfaces
The development of digital technologies in the 21st century is progressing continuously and new device classes such as tablets, smartphones or smartwatches are finding their way into our everyday lives. However, this development also poses problems, as these prevailing touch and gestural interfaces often lack tangibility, take little account of haptic qualities and therefore require full attention from their users. Compared to traditional tools and analog interfaces, the human skills to experience and manipulate material in its natural environment and context remain unexploited. To combine the best of both, a key question is how it is possible to blend the material world and digital world to design and realize novel hybrid interfaces in a meaningful way. Research on Tangible User Interfaces (TUIs) investigates the coupling between physical objects and virtual data. In contrast, hybrid interfaces, which specifically aim to digitally enrich analog artifacts of everyday work, have not yet been sufficiently researched and systematically discussed.
Therefore, this doctoral thesis rethinks how user interfaces can provide useful digital functionality while maintaining their physical properties and familiar patterns of use in the real world. However, the development of such hybrid interfaces raises overarching research questions about the design: Which kind of physical interfaces are worth exploring? What type of digital enhancement will improve existing interfaces? How can hybrid interfaces retain their physical properties while enabling new digital functions? What are suitable methods to explore different design? And how to support technology-enthusiast users in prototyping?
For a systematic investigation, the thesis builds on a design-oriented, exploratory and iterative development process using digital fabrication methods and novel materials. As a main contribution, four specific research projects are presented that apply and discuss different visual and interactive augmentation principles along real-world applications. The applications range from digitally-enhanced paper, interactive cords over visual watch strap extensions to novel prototyping tools for smart garments. While almost all of them integrate visual feedback and haptic input, none of them are built on rigid, rectangular pixel screens or use standard input modalities, as they all aim to reveal new design approaches. The dissertation shows how valuable it can be to rethink familiar, analog applications while thoughtfully extending them digitally. Finally, this thesisâ extensive work of engineering versatile research platforms is accompanied by overarching conceptual work, user evaluations and technical experiments, as well as literature reviews.Die Durchdringung digitaler Technologien im 21. Jahrhundert schreitet stetig voran und neue GerĂ€teklassen wie Tablets, Smartphones oder Smartwatches erobern unseren Alltag. Diese Entwicklung birgt aber auch Probleme, denn die vorherrschenden berĂŒhrungsempfindlichen OberflĂ€chen berĂŒcksichtigen kaum haptische QualitĂ€ten und erfordern daher die volle Aufmerksamkeit ihrer Nutzer:innen. Im Vergleich zu traditionellen Werkzeugen und analogen Schnittstellen bleiben die menschlichen FĂ€higkeiten ungenutzt, die Umwelt mit allen Sinnen zu begreifen und wahrzunehmen. Um das Beste aus beiden Welten zu vereinen, stellt sich daher die Frage, wie neuartige hybride Schnittstellen sinnvoll gestaltet und realisiert werden können, um die materielle und die digitale Welt zu verschmelzen. In der Forschung zu Tangible User Interfaces (TUIs) wird die Verbindung zwischen physischen Objekten und virtuellen Daten untersucht. Noch nicht ausreichend erforscht wurden hingegen hybride Schnittstellen, die speziell darauf abzielen, physische GegenstĂ€nde des Alltags digital zu erweitern und anhand geeigneter Designparameter und EntwurfsrĂ€ume systematisch zu untersuchen.
In dieser Dissertation wird daher untersucht, wie MaterialitĂ€t und DigitalitĂ€t nahtlos ineinander ĂŒbergehen können. Es soll erforscht werden, wie kĂŒnftige Benutzungsschnittstellen nĂŒtzliche digitale Funktionen bereitstellen können, ohne ihre physischen Eigenschaften und vertrauten Nutzungsmuster in der realen Welt zu verlieren. Die Entwicklung solcher hybriden AnsĂ€tze wirft jedoch ĂŒbergreifende Forschungsfragen zum Design auf: Welche Arten von physischen Schnittstellen sind es wert, betrachtet zu werden? Welche Art von digitaler Erweiterung verbessert das Bestehende? Wie können hybride Konzepte ihre physischen Eigenschaften beibehalten und gleichzeitig neue digitale Funktionen ermöglichen? Was sind geeignete Methoden, um verschiedene Designs zu erforschen? Wie kann man Technologiebegeisterte bei der Erstellung von Prototypen unterstĂŒtzen?
FĂŒr eine systematische Untersuchung stĂŒtzt sich die Arbeit auf einen designorientierten, explorativen und iterativen Entwicklungsprozess unter Verwendung digitaler Fabrikationsmethoden und neuartiger Materialien. Im Hauptteil werden vier Forschungsprojekte vorgestellt, die verschiedene visuelle und interaktive Prinzipien entlang realer Anwendungen diskutieren. Die Szenarien reichen von digital angereichertem Papier, interaktiven Kordeln ĂŒber visuelle Erweiterungen von UhrarmbĂ€ndern bis hin zu neuartigen Prototyping-Tools fĂŒr intelligente KleidungsstĂŒcke. Um neue DesignansĂ€tze aufzuzeigen, integrieren nahezu alle visuelles Feedback und haptische Eingaben, um Alternativen zu Standard-EingabemodalitĂ€ten auf starren Pixelbildschirmen zu schaffen. Die Dissertation hat gezeigt, wie wertvoll es sein kann, bekannte, analoge Anwendungen zu ĂŒberdenken und sie dabei gleichzeitig mit Bedacht digital zu erweitern. Dabei umfasst die vorliegende Arbeit sowohl realisierte technische Forschungsplattformen als auch ĂŒbergreifende konzeptionelle Arbeiten, Nutzerstudien und technische Experimente sowie die Analyse existierender Forschungsarbeiten
Understanding Personal Determinants of Lifting Strategy to Inform Movement-Focused Ergonomic Interventions
Introduction:
Lift training interventions are needed to reduce risk in jobs with non-modifiable demands, but to date have been generally ineffective. The lack of lift training effectiveness has been partially attributed to insufficient quality of content in the training programs. One way to improve the effectiveness of future lift training interventions may be to first understand what factors influence how a lifter chooses to move in the workplace (i.e., root causes). Previous research has identified that some lifters seem to consistently minimize resultant biomechanical exposures at the low back, but it is unclear why. If we can understand what personal factors influence how a lifter moves, lift training may be better targeted to address modifiable personal factors to minimize exposures during lifting.
The overarching objective of this thesis was to quantify the variability in low back exposures during lifting and to further determine if variability could be explained by personal factors including ability to perceive proprioceptive information, expertise, and a range of structural (i.e., body mass and stature) and functional (i.e., strength and flexibility) factors. With this understanding, I then aimed to identify which modifiable personal factors have the greatest prospective benefit of biasing a lifter to adopt a movement strategy with lower resultant biomechanical exposures using a computational modelling approach. The impetus for this thesis is to develop critical evidence as needed to inform the development of future, more efficacious lift training interventions.
Methods:
A cross-sectional between-subjects experimental design was used to address the thesis objectives. A sample of 72 participants were recruited to perform a lifting protocol consisting of both job-specific and generic lifting tasks. Purposive sampling was used to recruit participants with a range of experience and demographics. Ability to perceive sensory feedback was assessed using lift force and lift posture matching tests. The average and variability in resultant peak low back compression and A-P shear force, as well as kinematic features of whole-body movement strategy, during lifting were quantified as dependent variables. Consistently lower magnitudes of biomechanical exposures within a personal factor group would support that this group defines a movement objective that aims to minimize resultant exposures on the low back.
Using the experimentally obtained data, a probabilistic model was then developed that predicts the range of movement strategies and corresponding biomechanical exposures that are likely given a combination of underlying personal factors. Simulations were run to determine if improvements in any of ability to perceive sensory feedback, expertise, flexibility and/or strength capacity resulted in predicted reductions of low back exposure magnitude. Simulations were also conducted across a range of non-modifiable structural factors (i.e., sex, stature, and body mass) to evaluate whether the prospective benefit of improving modifiable factors to reduce low back exposures is generalizable across a working population.
Results:
Ability to perceive proprioceptive information (both force- and posture-sense) was associated with lower average and variability of low back loads. This suggests that individuals with better ability to perceive proprioceptive information may be more likely to define a movement objective to consistently minimize exposures. Albeit small effect sizes were observed with a maximum of 16% of variance in low back loads explained by proprioceptive ability.
Both structural and functional factors were significant predictors of average peak low back loads in lifting. However, except for females having lower variability in exposures than males, no other associations of personal factors to variability in loads was observed. These findings support that the investigated structural and functional factors can bias the range of available movement strategies to lifters, but donât necessarily influence towards a movement objective aiming to minimize low back loading.
No differences in average or variability in peak low back loads were observed across expertise groups. While this finding highlights that expertise doesnât seem to influence resultant exposures in lifting, differences in lifting kinematics were observed across groups suggesting other movement objectives may be defined as a function of expertise.
The prospective ability of reducing peak low back loads by improving modifiable personal factors was assessed using the developed probabilistic model. While improving proprioceptive ability, functional knee range of motion and strength were statistically associated with reducing low back loads, only improving functional knee range of motion was interpreted to have clinically significant effects on reducing low back loads during lifting.
Conclusion:
In this thesis the variance in peak low back loads during lifting that could be explained independently and inter-dependently by personal factors was investigated. These findings have implications for the development of future lift training interventions where improvements to functional knee range of motion may lead to retained lifting behaviour changes to reduce resultant peak low back loads during lifting. Secondary benefits may also come from improving proprioceptive ability and strength. Future lift training interventions can be developed to leverage these findings in practice where these results support that improvements to underlying flexibility, strength and proprioceptive ability seem to be important factors allowing individuals to adopt lower exposure lifting strategy
An investigation into mild traumatic brain injury identification, management, and mitigation
Concussion is classified as a mild traumatic brain injury which can be induced by biomechanical forces such as a physical impact to the head or body, which results in a transient neurological disturbance without obvious structural brain damage. Immediate access to tools that can identify, diagnosis and manage concussion are wide ranging and can lack consistency in application. It is well documented that there are frequent incidences of concussion across amateur and professional sport such as popular contact sports like rugby union.
A primary aim of this thesis was to establish the current modalities of âpitch sideâ concussion management, identification, and diagnosis across amateur and professional sporting populations. Furthermore, the research sought to understand existing concussion management and concussion experiences by means of recording the playerâs experiences and perceptions (retired professional rugby union players). These qualitative studies sought to gain insights into concussion experiences, the language used to discuss concussion and the duty of care which medical staff, coaching personnel, and club owners have towards professional rugby players in their employment.
In addition, possible interventions to reduce the incidence of concussion in amateur and professional sports were investigated. These included a âproof of conceptâ using inertial measurement units and a smartphone application, a tackle technique coaching app for amateur sports. Other research data investigating the use of neurological function data and neuromuscular fatigue in current professional rugby players as a novel means of monitoring injury risk were included in this research theme.
The findings of these studies suggest that there is an established head injury assessment process for professional sports. However, in amateur sport settings, this is not the existing practice and may expose amateur players to an increased risk of post-concussion syndrome or early retirement. Many past professional rugby union players stated that they did not know the effects of cumulative repetitive head impacts. They discussed how they minimised and ignored repeated concussions due to peer pressure or pressure from coaches or their own internal pressures of maintaining a livelihood. These data suggest that players believed that strong willed medical staff, immutable to pressures from coaching staff or even athletes themselves, were essential for player welfare and that club owners have a long-term duty of care to retired professional rugby union players. However, there are anecdotal methods suggested to reduce concussion incidence. For example, neck strengthening techniques to mitigate against collision impacts. There is, no longitudinal evidence to suggest that neck strength can reduce the impacts of concussion in adult populations . Additionally, other factors such as lowering the tackle height in the professional and amateur game is currently being investigated as a mitigating factor to reduce head injury risk.
The final theme of the thesis investigated possible methods to reduce injury incidence in amateur and professional athletes. The novel tackle technique platform could assist inexperienced amateur coaches on how to coach effective tackle technique to youth players. The findings from the neurological function data suggests that this may be an alternative way for coaches to assess and gather fatigue data on professional rugby union players alongside additional subjective measures and neuromuscular function data. Recently, the awareness of concussion as an injury and the recognition of concussion in many sports settings has improved. These incremental improvements have led to increased discussion regarding possible measures to mitigate the effects of concussion. There are many additional procedures to be implemented before a comprehensive concussion management is universally available, particularly in amateur and community sports. These necessary processes could be technological advances (e.g., using smart phone technology) for parents and amateur coaches to assist in the early identification of concussion or evidence-based concussion reduction strategies
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Wearable Technologies to Support Lower Limb Rehabilitation and Clinical Practice: user requirements, design and evaluation
The widespread adoption of wearable technologies in healthcare has the potential to bring about significant improvements. However, these technologies face design challenges when applied in real world settings and must be tailored to specific contexts of use and the needs of a diverse user base. This thesis investigates these issues in two distinct yet related areas of healthcare: neurorehabilitation and clinical movement analysis.
In neurorehabilitation, the research builds on previous work that demonstrated the effectiveness of wearable rhythmic haptic metronomes in improving and measuring the gait of individuals with neurological conditions in laboratory settings. This study takes this approach into the community and care home settings, using a technology probe method to identify the real-life requirements and design considerations of potential end-users and clinicians. This process identified a range of physical, sensory, and cognitive issues that are relevant to the design of the haptic metronomes, including haptic perception ability, wearability, interaction techniques, and individual preferences for body placement.
The second part of the thesis initially focused on the potential of active cueing for musculoskeletal conditions, but formative discussions with specialist physiotherapists and orthopaedic surgeons suggested that wearable clinical movement analysis would be a more suitable focus. Currently, proprietary systems for objectively assessing lower limb movements are either poorly suited or too expensive. To address this gap, non-proprietary software called MoJoXlab, paired with low-cost wearable inertial sensors was validated against high-end commercial software to perform clinical movement analysis. The results of these tests were compared across a range of activities, including walking, squatting, and jumping. MoJoXlab was further validated with a different sensor system, and limitations and nuances of supporting multiple sensor systems were identified.
Overall, this thesis highlights the importance of considering the needs and preferences of diverse users and the specific conditions and contexts in which wearable technologies will be used to effectively design and implement these technologies in healthcare
Optimising contextual factors in the practitioner-patient encounter in the management of osteoarthritis
Background
Contextual factors (CFs) related to the patient, healthcare practitioners, and their therapeutic relationship are integral to the overall treatment effect of any given intervention. In osteoarthritis (OA), around 75% of the treatment effect is directly attributable to CFs. Identifying and understanding the role of CFs may encourage healthcare practitioners to develop and enhance the contextual aspects of care, and thus enhance the overall treatment benefit.
Objectives
The overall aim of this research project is to develop a contextual enhancement package (CEP) that can be used to optimise the management of OA. To achieve this aim, the studies in this thesis aimed to realise the following objectives: [1] to identify and evaluate the current evidence for modifiable CFs that can improve clinical outcomes using quantitative systematic review and meta-analysis of randomised controlled trials (RCTs); [2] to explore and understand the experience and perspectives of patients and health practitioners about contextual enhancers in consultations for OA using qualitative systematic review and meta-aggregation; and [3] to obtain views and perspectives from clinicians, researchers, and public and patients on the identified CFs using an online survey and Public and Patient Involvement and Evaluation (PPI/E) meetings.
Methods
Quantitative systematic review: A systematic search was carried out, up until April 18th, 2019, on the following databases: MEDLINE via Ovid, EMBASE, AMED, PsycINFO and Cochrane library. RCTs comparing contextual enhanced interventions versus non-enhanced control in adults for any health conditions were searched. The outcomes included both self-reported outcomes and objectively measured outcomes. The effect size and 95% confidence interval were calculated using the standardised mean difference. Risk of bias was evaluated using the modified Cochrane tool. The random effects model was used to pool the results. The GRADE approach was used to assess the confidence in the body of evidence for each outcome assessed.
Qualitative systematic review: A systematic search was conducted between March 15 and May 18, 2020, on the following databases: MEDLINE via Ovid, EMBASE, AMED, PsycINFO and CINAHL. The search for unpublished studies included ProQuest Dissertations and Google Scholar. The search was not limited to any language or publication year. The Joanna Briggs Institute (JBI) methodology for quality assessment, study selection, data extraction and synthesis were used. Findings were assessed for credibility, categorised based on similarity in meaning and subjected to a meta-aggregation. The ConQual approach was used to assess the confidence of the synthesised findings.
Stakeholdersâ involvement: An online survey was conducted using Microsoft Forms software. The responses to the survey were collected between September 20 and October 15, 2021. Results were tabulated and analysed utilising Microsoft Excel. The study sought anonymous stakeholdersâ ratings and opinions. The survey involved a Likert scale question to rate the importance of each of the eight contextual factors identified in this project and an optional open-ended question about additional contextual factors related to practitioner-patient interaction that need to be considered.
PPI/E meetings: The PPI/E process in this research project took two forms of involvement. In the early stages of the project, in November 2019, the in-person PPI/E meeting aimed to consider the relevance of the research topic to the public and patients. The meeting communicated the research information (i.e., research question and topic) to patients with OA. Whereas, at the later stage of the research, in September 2021, patients exchanged information and participated by providing their opinion and input on the research outcomes in the online meeting.
Results
Quantitative systematic review: Of 3928 records generated from the systematic search, 25 trials (5632 participants) met the inclusion criteria, and 20 were included in this meta-analysis. Conditions studied included musculoskeletal [6], cardiovascular [3], asthma [2], irritable bowel syndrome [1], diabetes [1], chronic pain [1], acute pain [3], gynaecological conditions requiring day-care surgery [1], postoperative nausea [1], and in GP or hospital-based patients [6]. Three CFs were identified from these trials: empathy, patient involvement and positive communication. All were found to be effective for patient experience (i.e., satisfaction) (SMD 0.34; 95% CI 0.27, 0.42). Positive communication was also effective for symptoms (SMD 0.17, 95%CI 0.06, 0.28) but not objective outcomes (SMD 0.10, 95%CI -0.14, 0.34). According to the GRADE guidelines for assessing confidence in the findings of systematic reviews of interventions, the certainty of the evidence was rated low for symptoms and objective outcomes and very low for patient experience outcomes.
Qualitative systematic review: Of 1808 records generated from the systematic search of databases and grey literature, eight studies were included in the meta-aggregation. All included papers were moderate to high quality based on the JBI qualitative critical appraisal tool. Meta-aggregation generated three synthesised findings. According to the ConQual criteria for assessing confidence in qualitative review findings, all the synthesised findings' level of evidence was rated as moderate. The key, potentially modifiable, factors identified were empathy and positive communication; clear and relevant information provided by the health practitioner; patient expectation concerning their outcome and the consultation experience; active involvement of the patient in the consultation; sufficient consultation time; easy access to consultations; and health providers confidence.
Stakeholderâs involvement: Fifty healthcare providers from various professions and four patients with OA responded to the online survey. The healthcare providersâ professions included physicians, physiotherapists, health researchers, and podiatrist. All the respondents answered the Likert scale question, and 39 answered the optional open-ended question. The stakeholdersâ importance rating for each of the eight contextual factors identified from the quantitative and qualitative systematic reviews was high. Healthcare providers and patients with OA considered all factors essential and expanded their responses about how important these factors are in the open-ended question.
PPI/E meetings: The first meeting confirmed the importance and relevance of the research topic to a group of OA patients. Also, the PPI suggested some CFs (i.e., regular follow-up and referral) that were considered later in developing the search strategy for the qualitative systematic review. The second meeting obtained the PPI inputs on the CFs identified from previous reviews in the research project. The PPI/E supported the delivery of all the factors and suggested tailoring the factors to patient needs.
Conclusion
Eight contextual factors have been identified according to their therapeutic effects, clinical importance and stakeholdersâ perspectives. They are ready to be integrated to form a CEP. Further studies will be undertaken to develop an educational programme, test the feasibility of delivering CEP, and assess the clinical effectiveness and cost-effectiveness of CEP in people with osteoarthritis at the first instance
The effect of endurance training on mitochondrial function in Siberian huskies and Alaskan huskies
Teams of Alaskan huskies and Siberian Huskies are used to pull sleds and compete in long-distance races such as FinnmarkslĂžpet (1200 km) and the Iditarod (1600 km). That is an elite athlete performance, and their ability to conduct such extreme endurance challenges under arctic conditions is poorly understood. A previous study has shown that Alaskan huskies possibly have the highest values of mitochondrial oxidative phosphorylation (255±38 pmol/s*mg) and electron transfer system (254±37 pmol/s*mg) ever recorded in a mammalian skeletal muscle. This current study aimed to determine respiratory capacity in skeletal muscles from Siberian huskies and Alaskan huskies, off-season (August) and at the end of the racing season (March/April) to highlight physiological adaptations in the respiratory capacity of skeletal muscles arising as a result of selective breeding amongst huskies, as well as potential difference in the acclimatization responses to endurance training. Micro biopsy samples from M. biceps femoris were taken from non-raced and raced Siberian huskies and Alaskan huskies (2022â2023), and tissue homogenates were prepared for high resolution respirometry analyzes as well as citrate synthase activity assays to determine mitochondrial density. Respiratory capacity in skeletal muscle mitochondria from Siberian huskies and Alaskan huskies was higher during racing season as compared to off-season. Group mean values of electron transfer system (E) and oxidative phosphorylation (P) for were (P: 175.2±89.5, E: 164.2±92.1 pmol/s*mg) for raced Alaskan huskies and (P: 190.4±52.9, E: 180.0±56.7 pmol/s*mg) for raced Siberian huskies. The increase in aerobic capacity possibly results from a measured increase in muscle mitochondrial density, indicating a clear acclimatization response to endurance training. Alaskan huskies were shown to have higher respiratory capacity in their skeletal muscles as compared to that of Siberian huskies, based on carbohydrates associated substrates, possibly due to difference in their genetics. This was shown by a higher carbohydrate associated mitochondrial capacity for ETS (E) and OXPHOS (P) for non-raced Alaskan huskies (E: 63.0±45.5, P: 56.0±36.3 pmol/s*mg) as compared to non-raced Siberian huskies (E: 24.39±18.30, P: 23.5±16.2 pmol/s*mg). Non-raced Alaskan huskies had large sex differences in oxygen consumption which may be explained by mitochondrial substrate preference. This study is the first to determine mitochondrial respiration in Siberian huskies, while the mitochondrial respiration determined in the Alaskan huskies are in line with the earlier findings. Future studies should aim at investigating sexual dimorphism preference as well as substrate preference for Siberian husky mitochondria
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