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The associations between psychosocial factors at work and disordered eating behaviors among office workers.
No full textResearch problem: Contemporary office work is becoming increasingly exhausting due to technological progress, competition with artificial intelligence, and long sedentary work hours. These conditions may affect the psychosocial factors experienced by employees in the work environment and opposite. Such experiences may manifest in health behavior and lead to disordered eating. Although numerous studies have examined psychosocial factors, office-based work, and dietary patterns, there is a lack of research that reveals the associations between psychosocial work factors experienced by office workers and characteristics (disorders) of their eating behavior. Aim of the study: To examine the associations between psychosocial work factors and dietary patterns among office workers in Lithuania. Objectives: 1. Assess psychosocial work factors (job demands, job control, job role, workplace relationships, organizational changes, managerial and coworker support) among office workers and determine gender differences. 2. To assess the lifestyle characteristics of office workers and compare them by gender. 3. To evaluate the prevalence of disordered eating behaviors (cognitive restraint, uncontrolled eating, and emotional eating) among office workers and identify gender differences. 4. To evaluate the associations between psychosocial work factors and disordered eating behaviors among office workers. Hypotheses: 1.Individuals experiencing negative psychosocial work factors are more likely to exhibit disordered eating behaviors. 2. Women are more prone to disordered eating than men. Research method: Single-point epidemiological stud. Survey was carried out to collect data on psychosocial work factors and their influence on dietary patterns among office workers. A convenience sample was selected (N=382). The questionnaire consisted of four parts: demographic questions, the UK HSE Work Stress Assessment Questionnaire, the TFEQ-18-V2 questionnaire on disordered eating behavior, and a questionnaire assessing harmful habits and lifestyle. Correlation analyses between variables revealed statistically significant differences at p < 0.05. 7 Results: Psychosocial work factors among office workers showed statistically significant, though weak, negative associations with disordered eating behaviors. More favorable evaluations of job demands, coworker support, workplace relationships, clarity of job role, and change management were associated with lower levels of uncontrolled, cognitive, and emotional eating. The results indicate that a more favorable psychosocial work environment may be linked to healthier eating behavior. Conclusions: 1. The results showed that office workers had the clearest perception of their job role. Coworker support was also positively evaluated. The lowest scores were observed in the area of job demands. Slightly lower scores were also given to change management. Managerial support, job control, and workplace relationships were rated as average. Women rated job demands, coworker support, workplace relationships, and job role clarity more positively than men. However, there were no statistically significant gender differences in the assessment of job control, managerial support, or change management. 2.Among women, fewer were smokers, and more reported longer sleep duration and physical activity than men. The frequency of alcohol consumption did not differ significantly between genders, while self-assessed health was slightly better among men (though not statistically significant). Poorer health ratings among women were associated with higher workload, lower control, weaker coworker support, and worse workplace relationships. In the male group, health correlated with job demands, control, and coworker support. Men’s physical activity was associated with better health and more favorable evaluations of working conditions. Among women, subjective health significantly correlated with all forms of eating behavior—better health was linked to lower levels of uncontrolled, cognitive, and emotional eating. In both gender groups, sleep duration was related to eating behavior— shorter sleep was associated with poorer dietary control. 3. All three types of disordered eating— uncontrolled eating, cognitive restraint, and emotional eating—were found to be expressed at a moderate level. Emotional eating was the most prominent. No significant gender differences were found in eating behavior characteristics. 4. Psychosocial work factors among office workers showed statistically significant, though weak, negative associations with disordered eating behaviors. Job demands, coworker support, workplace relationships, job role clarity, and change management were associated with lower expression of uncontrolled, cognitive, and emotional eating. These associations were evident in the overall sample but were more frequent and stronger in the male group
Po rungtynių atliekamų mobilumo pratimų vaidmens raumenų atsistatymui ir traumų prevencijai futbolininkams analizė.
No full textBackground: Football players experience significant physical demands, leading to muscular fatigue, microtrauma, and increased injury risk. Effective recovery strategies are crucial for maintaining performance and reducing injuries. While passive methods like rest and cryotherapy are common, active recovery techniques, particularly post-game mobility exercises, have gained attention. These exercises incorporate dynamic stretching, joint mobilization, and controlled articular rotations to enhance recovery. Despite their growing use, their effectiveness in football remains underexplored. This study examines the role of post game mobility exercises in muscle recovery and injury prevention. Objectives: To evaluate the impact of post-game mobility exercises on (1) muscle soreness (VAS), (2) lower-body flexibility (ROM), and (3) perceived fatigue (RPE). Methodology: A cross-sectional study was conducted among competitive male football players (18–35 years) who played weekly matches. Participants followed a structured post game mobility exercise protocol. Outcomes were assessed using validated tools: the Visual Analog Scale (VAS) for soreness, range of motion (ROM) for the hip, knee, and hamstring flexibility, and the Rating of Perceived Exertion (RPE) scale. Results: Mobility exercises significantly improved hamstring flexibility (+15.09°; 21.8%), hip ROM (+12.58°; 13.6%), and knee ROM (+12.49°; 10.6%). Muscle soreness (VAS) decreased by 4.02 points (62.3%), while perceived exertion (RPE) dropped by 3.82 points (49.0%).A statistically significant but weak negative correlation (r = –0.169, p = 0.028) was found between the reduction in muscle soreness and the improvement in hamstring flexibility, suggesting that athletes who experienced greater soreness relief also showed better recovery in hamstring extensibility. No statistically significant correlations were found between changes in muscle soreness and changes in hip or knee joint range of motion. These findings support mobility exercises in reducing tightness, restoring joint function, alleviating pain, and enhancing recovery. Conclusions: Incorporating post-game mobility exercises can optimize muscle recovery, improve flexibility, and may reduce injury risk in football players. These findings highlight the importance of active recovery strategies in maintaining athletic performance and preventing injuries. Further studies should explore long-term benefits and variations in mobility protocols
Effect of mirror therapy on upper extremity function in stroke patients: systematic review.
No full textBackground: After stroke, approximately 80 proc. of individuals experience motor impairments, often affecting the upper limb and interfering with daily activities. Restoring upper limb function is a key goal in stroke rehabilitation. The aim of this study: to evaluate the effect of mirror therapy on upper limb motor function. The tasks of this study: 1. Identify randomised controlled trials assessing the effectiveness of mirror therapy in post-stroke hand motor recovery; 2. Evaluate the impact and effect size of mirror therapy intervention on hand motor function; 3. Provide recommendations for further systematic analyses. Hypothesis of this study: Mirror therapy will have at least a moderate effect size in improving the recovery of upper limb motor function in patients after stroke. Study methods: included randomised controlled trials compared upper extremity mirror therapy with other rehabilitation methods. The effect size was calculated using Cohen‘s D formula. Results: a total of 29 randomised controlled trials were analysed. Motor function outcomes showed a small effect size with ARAT, WMFT-Time, and FMA-UE evaluations; a moderate effect size with MFT and BBT evaluations; a large effect size with WMFT-FAS evaluations. The evaluation of additional indicators revealed a small effect size with BRS, FIM, MBI, and MAS evaluations, while the MI assessment indicated a large effect size. Conclusion: Effect of Mirror Therapy on Upper Extremity Function in Stroke Patients: Systematic Review. 1. A total of 29 randomised controlled trials were identified and analysed. 2. Mirror therapy is particularly effective in improving hand dexterity and motor function, but its impact on reducing spasticity is limited. 3. Future systematic reviews are recommended to improve methodological quality, increase sample size, and optimise mirror therapy parameters
A 10‐year longitudinal study of muscle morphology and performance in masters sprinters /
No full textBoth longitudinal and cross‐sectional studies have demonstrated that muscle mass, strength and power are lost with ageing. Although longitudinal studies have shown changes in muscle morphology and function in sedentary, healthy active and endurance‐trained older people, less is known about such age‐related changes in sprint athletes. It has been proposed that active older people may provide a better study of healthy ageing not confounded by factors of inactivity and other unhealthy behaviours. Given that the training regimens of masters sprinters consist of strength and sprint training that elicit gains in muscle force, power and mass, sprinters may not suffer from measurable decrements in muscle strength, functional performance or morphology over a 10‐year period
Temperatūrinių manipuliacijų poveikis jaunų vyrų griaučių raumenų funkcijai ir šiluminiam streso atsakui.
No full textTemperature manipulation refers to the modulation of environmental temperature, which leads to changes in body temperature (Cheshire, 2016; Osilla, Marsidi & Sharma, 2018; Cramer, Gagnon, Laitano & Crandall, 2022). These thermal variations can influence several physiological processes, including muscle function, metabolic activity, inflammation, and recovery processes (Bennett, 1984; Versey, Halson & Dawson, 2013; Flouris, Webb & Kenny, 2015; Castellani & Young, 2016; Rodrigues, Trajano, Stewart & Minett, 2022). Both cooling and heating strategies are widely applied in public health settings, and are utilized by athletes to enhance recovery after physical exercise (Lan, Qian, Lian & Lin, 2018; Brunt & Minson, 2021; Chaillou et al., 2022). The ability to maintain effective thermoregulation contributes to well-being by ensuring thermal balance and stable core body temperature under varying environmental conditions (Nagashima, Tokizawa, Uchida, Nakamura-Matsuda & Lin, 2012; Tansey & Johnson, 2015; Flouris & Schlader, 2015; Cramer et al., 2022). Thermal stress occurs when changes in ambient temperature lead to increases or decreases in core temperature, skin temperature (Tsk), or both, significantly challenging the body’s ability to maintain homeostasis (Kenny & Flouris, 2014; Greaney, Kenney & Alexander, 2016). Passive cold (CWI) or hot (HWI) water immersions and exertional (exercise-induced) heating are among the most commonly used and evidence-based methods in temperature modulation strategies (Davies & Young 1983; Nybo, Rasmussen & Sawka, 2014; Racinais, Wilson & Periard, 2017; Tipton, Collier, Massey, Corbett & Harper, 2017; Sautillet et al., 2024; O’Brien, Goosey-Tolfrey & Leicht, 2024; Wallace et al., 2024). These interventions can induce thermal stress, a physiological strain arising from an imbalance between heat production and heat loss when the body is unable to maintain a stable core temperature (Cramer & Jay, 2016). However, the mechanisms underlying the effects on neuromuscular function, recovery and thermal stress are not fully understood, especially regarding the duration and mode of thermal exposure. Understanding how temperature changes affect skeletal muscle function, contractile properties or thermal stress is essential for individuals exposed to hot and cold environments during work and sports activities (Cheung, Lee & Oksa, 2016; Racinais, Cocking & Periard, 2017; Ashworth, Cotter & Kilding, 2020). Identifying the main physiological, neuromuscular and thermal stress responses can guide the development of effective strategies to prevent detrimental effects such as hypothermia or hyperthermia (Nybo, 2008; Cahill, Kalmar, Pretorius, Gardiner & Giesbrecht, 2011; Fudge, Bennett, Simanis & Roberts, 2015). Changes in core temperature and muscle temperature (Tmu) during heating and cooling interventions can influence skeletal muscle function (Bergh & Ekblom, 1979; Brazaitis, Skurvydas, Vadopalas, Daniusevičiūtė & Senikienė, 2011; Brazaitis et al., 2014; Periard, Eijsvogels & Daanen, 2021; Rodrigues, Trajano, Wharton, Orssatto & Minett, 2020) and recovery (Roberts, Nosaka, Coombes & Peake, 2014; Cheng et al., 2017). Temperature manipulation can be achieved through passive methods (e.g., water immersion) or exertional means (e.g., physical exercise), both of which modulate muscle function, thermoregulatory responses (Morton et al., 2007; Rodrigues et al., 2020) and recovery from fatigue (Mika et al., 2016; Moore et al., 2022). Different heating modalities can lead to distinct changes in Tmu and core temperature (Drust, Rasmussen, Mohr, Nielsen & Nybo, 2005; Rodrigues, Trajano, Wharton, Orssatto & Minett, 2021). During physical exercise, core temperature and Tmu rise due to increased metabolic activity and blood flow, while passive heating elevates Tmu and core temperature primarily due to heat transfer from the hot water to the body through convection, and to a lower extent, from an increased metabolic rate (Periard et al., 2021; Cramer et al., 2022). During thermal stress, the hypothalamus is the central regulator of core temperature and acts as a thermostat, triggering various neuronal and physiological mechanisms to control body temperature and enhance heat loss from the body, including vasodilation, increased blood flow to the skin, sweating and the dissipation of heat from the skin through evaporation (Cramer et al., 2022). Both heating modalities result in similar physiological responses, including elevated core temperature and Tsk, sweating, blood redistribution from the core to the skin, and the release of stress hormones such as increased prolactin secretion (Brenner, Zamecnik, Shek & Shephard, 1997; Low, Purvis, Reilly & Cable, 2005; Jimenez et al., 2007). Prolactin is often used as an indirect marker of central fatigue and heat-related stress (Low et al., 2005; Mundel, Hooper, Bunn & Jones, 2006). The increase in prolactin levels during heat stress appears to be influenced by elevated core temperature and Tsk (Brisson et al., 1986; Melin, Cure, Pequignot & Bittel, 1988; Mundel et al., 2006). Despite the essential role of thermoregulatory mechanisms in managing body heat during both exertional and passive heating, it remains unclear whether similar prolactin responses occur when core temperature is closely matched, but Tsk differs between exertional and passive heating. In addition to hormonal responses to heat, skeletal muscle function is also highly sensitive to temperature fluctuations (Asmussen, Bonde-Petersen & Jorgensen, 1976; Stanley, Kraemer, Howard, Armstrong & Maresh, 1994; Brazaitis et al., 2011). Exposures to HWI improve muscle blood flow, vasodilation and raise core temperature and Tmu, which enhances muscle contractile properties (Amin et al., 2022; Eimantas, Ivanove, Solianik & Brazaitis, 2022; Rodrigues et al., 2022) and promotes recovery processes by increasing muscle glycogen resynthesis (Cheng et al., 2017). Conversely, exposure to CWI reduce muscle metabolic activity, femoral blood flow and increase cutaneous vasoconstriction (Ihsan, Watson, Lipski & Abbiss, 2013; Mawhinney et al., 2017). This leads to decreased Tmu, which can shift muscle function towards a slower contractile profile and reduce muscle force production (Davies, Mecrow & White, 1982; De Ruiter, Jones, Sargeant & De Haan, 1999; Brazaitis et al., 2014). CWI is an effective recovery strategy after highintensity exercise, improving muscle power, reducing muscle soreness and enhancing fatigue recovery (Moore et al., 2022). However, these adjustments may be influenced by the duration of exposure, water temperature and the type of immersion (single or intermittent) (Brazaitis et al., 2011; Brazaitis et al., 2014; Castellani & Young, 2016). Studies indicate that cooling and heating can have distinct effects on muscle function, including electrically evoked, maximal voluntary isometric contractions (MVIC), dynamic voluntary contraction forces and contractile properties following immersions (Bergh & Ekblom, 1979; Davies et al., 1982; De Ruiter et al., 1999; Morrison, Sleivert & Cheung, 2004; Thomas, Cheung, Elder & Sleivert, 2006; Brazaitis et al., 2011; Brazaitis et al., 2019). In the literature, studies on local cooling and heating and their effects on muscle force typically use single water immersions (Edwards et al., 1972; Davies et al., 1982; Brazaitis et al., 2011), while only a few studies investigated prolonged effect on temperature changes (Rodrigues et al., 2021; Rodrigues, Orssatto, Trajano, Wharton & Minett, 2023; Baranauskiene, Wang, Eimantas, Solianik & Brazaitis, 2023). To date, research on the effects of heating and cooling on the time course of voluntary and electrically induced muscle force changes has been limited to studies examining the acute (~45 min) impact of HWI and CWI on skeletal muscle function (Brazaitis et al., 2011). The neuromuscular and physiological effects of cold and heat under varying durations and conditions remain insufficient. Duration plays a critical role in modulating physiological responses and neuromuscular function. A single exposure typically induces immediate physiological responses (e.g., changes in Tsk and Tmu), while prolonged immersion may lead to cumulative effects that could influence systemic thermoregulation and neuromuscular function. In the current literature, the majority of the studies investigate a single exposure, limiting the ability to directly compare the effects of acute and prolonged immersion under controlled experimental conditions. To date, the physiological and biological responses to passive and active heating, with a particular focus on muscle contractile properties, voluntary and involuntary force production, thermal perception, and endocrine responses remain a relevant area of research. Investigating both acute and prolonged durations within controlled experimental settings would contribute to a better understanding of the underlying mechanisms that could be applied in clinical and practical fields. Aim of research The main aim of the research was to determine the effects of heating and cooling of varying durations on skeletal muscle function and thermal stress responses in recreationally active young males. Research objectives: 1. To compare prolactin levels and thermal perceptions between active (exertional, Exer-H) and passive (exogenous, Exo-H) heating that produce a closely matched increase in core temperature, but differing changes in Tsk in young recreationally active males. 2. To investigate the impact of passive heating induced by single and intermittent/prolonged HWI on muscle force and contractile function in unfatigued state and during the development of fatigue resulting from electrically induced contractions. 3. To investigate the impact of moderate muscle cooling induced by single and intermittent/prolonged CWI on muscle force and contractility in unfatigued state and during the development of fatigue resulting from electrically induced contractions. 4. To investigate the effect of acute and prolonged heating and cooling on skeletal muscle fatigue development and recovery.Research hypothesis: 1. Exo-H (HWI up to the waist) would elicit higher prolactin responses and thermal perceptions than Exer-H (cycling), due to greater lower-body Tsk. 2. Intermittent/prolonged HWI would induce more pronounced central fatigue and a greater reduction in voluntary muscle activation than single HWI, with minimal additive effects on muscle contractile properties. 3. Intermittent/prolonged CWI would have a less detrimental effect on muscle contractility than single CWI, possibly due to a moderate reduction in Tmu and reduced vasoconstriction. 4. Both acute and prolonged heating would reduce muscle force during fatiguing exercise more than cooling, and cause slower recovery under heating conditions. Originality, novelty and practical significance of the research No previous studies have directly compared physiological, biological and perceptual responses between Exo-H (lower body HWI) and Exer-H (physical exercise) heating that elicit closely matched elevations in rectal temperature (Trec).While prolactin responsesto passive heating are well-documented, its behavior during exercise in the heat remains unclear because of inconsistent findings. Furthermore, although prolactin levels during heat stress are largely influenced by increases in core temperature and Tsk, it is still unknown whether this relationship in consistent when core temperature increases are matched but Tsk responses differ. Additionally, no previous studies have investigated the effects of intermittent/prolonged heating and cooling lasting 300 minutes on skeletal muscle function and recovery. Therefore no studies have compared the effects of single and intermittent/prolonged heating and cooling on muscle force, contractile properties, fatigue and recovery. Understanding these aspects is crucial for athletes, coaches, military personnel, and occupational workers who face thermal stress during work or sports activities. CONCLUSIONS 1. Prolactin levels increase more markedly during Exo-H compared to Exer-H, despite a closely matched elevation of Trec. This result could be explained by the large differences in Tsk of the lower limbs between the two heating conditions. Moreover, thermal perceptions are not differently affected during Exer-H and Exo-H. Our findings suggest that sweating sensation could partially reflect the hydration status, while thermal comfort and sensation may be partly connected to changes in prolactin levels. 2. Single or intermittent/prolonged hot water immersion enhances muscle contractile properties and accelerates muscle relaxation in the unfatigued state without impairing muscle force during maximal voluntary isokinetic concentric contraction and maximal voluntary isometric contraction, despite a moderate reduction in voluntary activation. Heating-induced changes in muscle contractile function are not further augmented by prolonged exposure when thermal stress is moderate. 3. Intermittent/prolonged cold water immersion induces a less pronounced fast-to-slow contractile transition compared to single cold water immersion, and this may result from the reduced vasoconstriction response and enhanced blood perfusion of the superficial muscle vessels, which could ultimately limit the reduction of superficial Tmu. 4. Although hot water immersion effectively increases body temperature, it may significantly impair neuromuscular recovery more than cold water immersion or passive rest
Evidence-based exercise recommendations to improve functional mobility in older adults - A study protocol for living systematic review and meta-analysis /
No full textBackground and objectives: This is a protocol for a living systematic review and meta-analysis.This review will assess the effects of state-of-the-art exercise interventions designed to promote functional mobility. Therefore, after identifying all potential interventions, we will use the F.I.T.T. principles (frequency, intensity, time, type) as well as the physical and health status of the participants as moderators to analyse the mechanisms for the positive benefits of exercise interventions.The main research questions are:Which exercise types are most beneficial for improving functional mobility in various populations of older adults?Which physical exercise characteristics in terms of frequency, intensity, time and duration will achieve the greatest benefit in terms of the defined outcomes, i.e, the functional mobility of older adults? Methods: The systematic literature research according to PRISMA guidelines will search databases like MEDLINE, APA Psych-Info and Web of Science.Inclusion criteria are: healthy older people ≥ 50 years, randomized-controlled trials including exercise intervention and a walking or mobility assessments (eg., TUG, SPPB) as an outcome measure. A preliminary search revealed more than 33,000 hits that will be screened by pairs of independent reviewers. The results will be summarized according to the effects regarding functional mobility and potential dose-response relations via respective meta-analysis. Conclusion: The systematic review will comprise the knowledge of the existing literature with regards to the effects of the physical activity interventions compared to an active or inactive control group.We will summarize the effects with respect to the F.I.T.T.. They provide a foundation for structuring an optimal exercise training program. If possible, we will also compare interventions from the different categories (eg. cardiovascular, resistance, motor-coordinative, multicomponent or mind-body exercise) as a network analysis and report the influence of moderator variables. Based on the results evidence-based guidelines following GRADE for physical exercise interventions to improve functional mobility in older adults will be provided
Exploring the link between body appreciation and health-related lifestyle in adolescents: a cross-sectional study /
No full textAdolescence is a critical developmental stage at which body image and lifestyle behaviours intersect. Research shows that having a positive body image during this period is linked to better mental health and certain aspects of a healthy lifestyle. However, more empirical evidence is needed, especially concerning boys. This cross-sectional study explored the association between body appreciation (BA) and lifestyle factors in a large sample of Lithuanian adolescents. These associations were examined while controlling for body mass index (BMI), and the role of sex in these relationships was evaluated. A cross-sectional study involved 1412 adolescents (59.6% girls) aged 16–17 years (mean age of 16.97 ± 0.46 years). Participants completed questionnaires assessing BA, self-esteem, life satisfaction and lifestyle factors such as physical activity and perceived fitness, sleep duration, screen time and disordered eating (DE) attitudes and behaviours. Data were analysed using descriptive statistics, analysis of covariance (ANCOVA), and binary logistic regression analysis. Higher BA was associated with greater life satisfaction, self-esteem, perceived physical fitness and healthier eating behaviours independent of BMI in boys and girls. Adolescents with high BA had significantly higher odds of participating in sports, having a healthy BMI, accurate body weight estimation, good self-rated health and non-smoking behaviours compared to those with low BA. BA was also associated with healthier sleeping hours, lower screen time and lower unhealthy and DE behaviour in girls. Boys with high BA were more likely to abstain from alcohol. Interaction effects indicated that the effect of BA on self-esteem, BMI and DE behaviours was stronger in girls than in boys. BA is strongly linked to positive lifestyle outcomes and self-esteem in adolescents, particularly in girls. The findings of this study indicate that initiatives designed to promote healthy lifestyles among adolescent boys and girls may be enhanced by the incorporation of education on positive body image. Interventions should be tailored to gender-specific needs, emphasizing prevention of dysfunctional eating for girls, and reducing substance use for boys. Incorporating body-positive education into schools and health programs can help create supportive environments that enhance both psychological well-being and physical health
Evolution and challenges of sport policy in Lithuania: a historical and contemporary analysis /
No full textThis paper examines the evolution and contemporary challenges of sport policy in Lithuania, emphasizing the interplay between politics and national planning. It provides a historical overview of Lithuanian sport policy development, particularly focusing on the transition from the Soviet system to a democratic model after regaining independence in 1990. Key components, stakeholders, and the structure of the current Lithuanian sport system are analyzed, highlighting the critical role of sports science. The study identifies significant gaps in academic research on sport policy and underscores the necessity for more comprehensive studies in this field. It discusses the main challenges influencing the future of Lithuanian sport policy, including political instability, bureaucratic influence, and limited stakeholder involvement. The purpose of this paper is to address a gap in the academic literature and enhance the scientific understanding of sport policy development in Lithuania. Accordingly, this study seeks to answer the following research question: How has Lithuanian sport policy evolved since independence, and what political and institutional factors currently shape its development and implementation? By exploring this question, the study aims to fill a notable gap in academic literature and contribute to a deeper understanding of sport governance in post-socialist European contexts
Metabolic stress and muscle mechanics: Acute response of isolated soleus and EDL muscles to prolonged fasting in mice with distinct muscle phenotypes /
No full textProlonged fasting impacts skeletal muscle by inducing atrophy, thereby limiting contractile capacity and altering tissue mechanical behavior. This study investigated the effects of 48 h of fasting (FAS) versus ad libitum food consumption (CON) on the mechanical properties of fast-twitch (extensor digitorum longus, EDL) and slow-twitch (soleus, SOL) muscles in three mouse strains with distinct muscle phenotypes: C57BL/6J (normal-sized), BEH+/+ (larger muscles), and BEH (myostatin-deficient with markedly larger muscles). Isolated SOL and EDL were subjected to 100 isometric–eccentric contraction cycles, and peak and specific force, rate of force development, fatigue, stiffness, and tangent modulus were assessed. Fasting significantly reduced muscle size and force production capacity (isometric and eccentric) across all strains (p<0.05). SOL muscles showed a greater decline in tetanic force (fatigue index: SOL 67% vs. EDL 33%, p<0.05), while BEH mice exhibited the steepest contractile impairment (p<0.05). Fasting also reduced stiffness and tangent modulus across all strains and muscle types (p<0.05). These findings demonstrate that fasting consistently impairs contractile and mechanical properties of skeletal muscle, with slow-twitch muscles and larger muscles phenotypes being particularly vulnerable. Muscle type and genetic background thus play key roles in determining the extent of functional decline under metabolic stress
