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Inter-person differences in isometric coactivations of triceps surae and tibialis anterior decrease in young, but not in older adults after 14 days of bed rest
Matjaž Divjak, Gašper Sedej, Nina Murks, Mitja Gerževič, Uroš Marušič, Rado Pišot, Boštjan Šimunič, Aleš Holobar, 2022, izvirni znanstveni članek

Povzetek: We examined activation patterns of the gastrocnemius medialis (GM), gastrocnemius lateralis (GL), soleus (SO), and tibialis anterior (TA) muscles in eight older (58.4 ± 3.3 years) and seven young (23.1 ± 2.9 years) participants, before and after 14 days of horizontal bed rest. Visual feedback on the exerted muscle torque was provided to the participants. The discharge patterns of individual motor units (MUs) were studied in three repetitions of isometric plantar flexion at 30 and 60% of Maximum Voluntary Contraction (MVC), before, and 1 day after the 14-day bed rest, respectively. In the GL and GM muscles, the older participants demonstrated higher MU discharge rates than the young, regardless of the contraction level, both before and after the bed rest. In the TA and SO muscles, the differences between the older and young participants were less consistent. Detailed analysis revealed person-specific changes in the MU discharge rates after the bed rest. To quantify the coactivation patterns we calculated the correlation coefficients between the cumulative spike trains of identified MUs from each muscle, and measured the root mean square difference of the correlation coefficients between the trials of the same session (intra-session variability) and between different sessions (inter-session variability) in each participant (intra-person comparison) and across participants (inter-person comparison). In the intra-person comparison, the inter-session variability was higher than the intra-session variability, either before or after the bed rest. At 60% MVC torque, the young demonstrated higher inter-person variability of coactivation than the older participants, but this variability decreased significantly after the bed rest. In older participants, inter-person variability was consistently lower at 60% than at 30% MVC torque. In young participants, inter-person variability became lower at 60% than at 30% MVC torque only after the bed rest. Precaution is required when analyzing the MU discharge and coactivation patterns, as individual persons demonstrate individual adaptations to aging or bed rest.
Ključne besede: high density electromyography, muscle disuse, motor units, discharge rate, aging
Objavljeno v DiRROS: 05.09.2022; Ogledov: 76; Prenosov: 34
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Decomposition of tensiomyogram and comparison with torque twitch responses after post-activation potentiation
Ensar Abazović, Armin Paravlić, Damir Zubac, Erol Kovačević, Boštjan Šimunič, 2022, izvirni znanstveni članek

Povzetek: Objectives: This study evaluates the effect of post-activation potentiation (PAP) after 5x5s maximal voluntary isometric contractions (activation stimulus, AS) on tensiomyography (TMG) and torque twitch contractile parameters of vastus lateralis (VL) and medialis (VM), respectively. Further, we validated the decomposition of TMG response to separate responses of three fiber types. Methods: 15 healthy individuals participated in this study (40% women; age 19±2.3 years). A decomposition of VL TMG response was done after optimal fitting of three exponential curves. Results: We found main effects in contraction time (Tc) for muscle, method and time. Furthermore, we found interactions between muscle*method, method*time and muscle*method*time. Compared to PRE AS, we found shorter TMG Tc in VL and VM during the first two minutes after AS. Torque Tc remained unchanged in VL, while it increased in VM within 30 seconds after AS. A decomposition of VL TMG response confirmed PAP effects being present only in decomposed type IIb muscle fibers. Conclusion: The TMG is a sensitive method to detect PAP effects with a sensor mounted directly above the muscle belly. After the decomposition of the TMG signal to three separate muscle fiber phenotypes, we provided a non-invasive insight in the contribution of each muscle fiber phenotype to the PAP of the whole muscle.
Ključne besede: skeletal muscles, fast-twitch fibers, post-activation potentiation, decomposition, tensiomyography
Objavljeno v DiRROS: 05.09.2022; Ogledov: 87; Prenosov: 37
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Does an active lifestyle matter? : a longitudinal study of physical activity and health-related determinants in older adults
Kaja Teraž, Saša Pišot, Boštjan Šimunič, Rado Pišot, 2022, izvirni znanstveni članek

Povzetek: Introduction: It is well-known that regular physical activity, and thus an active lifestyle, has positive eects on aging and general wellbeing. However, the question remains as to whether regular or increased physical activity can improve self-perception of health status and quality of life in older adults. Methods: We conducted a longitudinal study on a group of active older adults between 2013 and 2021. At baseline, i.e., the 1st measurements (baseline), 147 participants were enrolled (mean age 68.4 ± 5.6). After 8 years, in 2021 (follow up), 52 older adults (mean age 75.9 ± 5.3 years) were measured. For the purpose of this study, we included 52 older adults participated at both time-points. For both measurements, participants reported their physical activity and sedentary behavior using the Global physical activity questionnaire (GPAQ), socio-demographic and environmental determinants, recording their self-perception in terms of overall wellbeing. Furthermore, we conducted a qualitative study using semi-structured interviews to obtain subjective data on the changes and events that may have aected physical abilities and general health over an 8-year period. Results: At the follow up, participants reported lower physical activity and sedentary behavior compared to baseline, but still met health-enhancing physical activity (HEPA) standards for total self-reported physical activity (>3,000 METmin/week). In addition, they rated their overall health (p < 0.001), physical fitness (p < 0.001), psychological wellbeing (p < 0.001) and overall quality of life (p < 0.001) as better. The qualitative data confirmed that the 8-year period involved changes in physical activity. Specifically, they have continued to carry out physical work (gardening, working in the vineyards, olive groves), but previously organized physical activities were replaced by walks in nature, which probably also influenced the reduction of sedentary behavior. Conclusion: After 8 years, as expected, participants reported a decrease in physical activity and a lower level of sedentary behavior. It appears from the interview that healthy older adults filled their days with daily tasks and found more time for walking. Individuals who were more active in the past 8 years also reported better overall health and wellbeing. Selected variables correlated with an active lifestyle and better perceptions of quality of life.
Ključne besede: older adults, aging, physical activity, wellbeing, quality of life, leisure time
Objavljeno v DiRROS: 30.08.2022; Ogledov: 53; Prenosov: 42
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Reliability and validity of 30-15 intermittent fitness test for cardiorespiratory fitness assessment among infantry members of Slovenian armed forces : ǂa ǂstudy protocol
Armin Paravlić, Boštjan Šimunič, Rado Pišot, Samo Rauter, Janez Vodičar, 2022, izvirni znanstveni članek

Povzetek: Introduction: Cardiorespiratory fitness (CRF) testing is routinely performed by most armed and tactical forces around the world as part of their recruitment process for new members or simply as an annual examination of their personnel. A 2-mile run (2MR) test is among the most commonly used. However, as it is performed outdoors, weather, climate, and terrain can influence the results and often limit the maximum performance. Also, this test has been shown to be difficult for individuals because the pacing strategy is self-paced. As such, it does not reflect the real situation on the battlefield, where most activities are externally driven by the environment and the enemy. Therefore, we believe that the 30-15 Intermittent Fitness Test (30-15IFT) may be a suitable tool for measuring CRF and battle readiness of military personnel. Moreover, given the importance of visual attention to military personnel we aim to investigate the differences in visual attention between better and less physically prepared infantry members and its corresponding response to maximal endurance running test. Methods and analysis: This randomized cross-over study using a within-subjects test-retest design will enroll 32 infantry members of the Slovenian Armed Forces. To investigate the reliability and validity of the 30-15IFT test, an incremental treadmill test (TR), a 2MR test, and two identical 30-15IFT will be performed in randomized order. Additionally, participants will be subsequently divided into two groups based on their score on the Army Physical Fitness Test (APFT), whereas differences in visual attention will be assessed by using the d2 test. The primary analysis will assess differences in key physiological outcomes between the different CRF tests (TR vs. 2MR vs. 30-15IFT). In addition, the relative reliability of all dependent variables between two 30-15IFT trials will be estimated by interclass correlation coefficient (ICC), while relationship between maximal oxygen uptake, heart rate and maximal running speed of 30-15IFT, TR and 2MR will be assessed using Pearson’s correlation.
Ključne besede: Slovenian armed forces, running endurance, visual attention, cardiorespiratory fitness assessment, intermittent fitness tests, reliability, validation
Objavljeno v DiRROS: 27.07.2022; Ogledov: 173; Prenosov: 92
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Irisin attenuates muscle impairment during bed rest through muscle-adipose tissue crosstalk
Andrea D'Amuri, Juana Maria Sanz, Stefano Lazzer, Rado Pišot, Boštjan Šimunič, Gianni Biolo, Giovanni Zuliani, Mladen Gasparini, Marco Vincenzo Narici, Bruno Grassi, Carlo Reggiani, Edoardo Dalla Nora, Angelina Passaro, 2022, izvirni znanstveni članek

Povzetek: Simple Summary: Irisin is a known myokine secreted mainly by the muscle that is produced after physical activity. It induces browning in the adipose tissue with a consequent increase in mitochondrial oxidation of lipids and reduction of insulin resistance; thus, it has been hypothesized that irisin was the molecule mediating most of the beneficial effects related to exercise on adipose tissue and consequently on the whole organism. In our study we observed that extreme physical inactivity induces the loss of muscle mass and function, and an increase in the body adipose tissue as expected. However, of note, circulating irisin levels were increased secondary to enhanced irisin synthesis mainly from adipose tissue rather than muscle. In addition, subjects who produced more irisin had reduced muscle impairment. Therefore, our hypothesis is that there is negative feedback within the muscle-adipose tissue crosstalk, specifically not only does the muscle influence the adipose tissue through irisin during exercise, but also the adipose tissue protects the muscle during inactivity.Abstract: The detrimental effect of physical inactivity on muscle characteristics are well known. Irisin, an exercise-induced myokine cleaved from membrane protein fibronectin type III domain-containing protein-5 (FNDC5), mediates at least partially the metabolic benefits of exercise. This study aimed to assess the interplay between prolonged inactivity, circulating irisin, muscle performance, muscle fibers characteristics, as well as the FNDC5 gene expression (FNDC5ge) in muscle and adipose tissue among healthy subjects. Twenty-three healthy volunteers were tested before and after 14 days of Bed Rest, (BR). Post-BR circulating levels of irisin significantly increased, whereas body composition, muscle performance, and muscle fiber characteristics deteriorated. Among the subjects achieving the highest post-BR increase of irisin, the lowest reduction in maximal voluntary contraction and specific force of Fiber Slow/1, the highest increase of FNDC5ge in adipose tissue, and no variation of FNDC5ge in skeletal muscle were recorded. Subjects who had the highest FNDC5ge in adipose tissue but not in muscle tissue showed the highest circulating irisin levels and could better withstand the harmful effect of BR.
Ključne besede: physical inactivity, bed rest, FNDC5 gene expression, myokines, sarcopenia, muscles fiber
Objavljeno v DiRROS: 07.07.2022; Ogledov: 179; Prenosov: 116
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Dietary acid load but not Mediterranean diet adherence score is associated with metabolic and cardiovascular health state : ǂa ǂpopulation observational study from Northern Italy
Juana Maria Sanz, Domenico Sergi, Simona Colombari, Eleonora Capatti, Roberta Situlin, Gianni Biolo, Filippo Giorgio Di Girolamo, Stefano Lazzer, Boštjan Šimunič, Rado Pišot, Angelina Passaro, 2022, izvirni znanstveni članek

Povzetek: Diet plays a pivotal role in shaping the trajectory of chronic diseases. In this regard, the Mediterranean diet has been widely shown to exert beneficial effects on cardiometabolic health. On the contrary, the Western diet, which has also been reported to be an acidogenic dietary pattern, elicits detrimental effects on both metabolic and cardiovascular (CV) health. However, the role of dietary acid load (DAL) as a predictor of cardiometabolic prognosis remains to be elucidated. Thus, this study aims to compare Mediterranean diet adherence (MDA) and DAL focusing on their relationship with metabolic and CV prognosis. A total of 448 individuals aged 55–80 years were grouped depending on their MDA, assessed using food frequency questionnaires, or DAL, evaluated using potential renal load acid (PRAL) and net-endogenous acid production (NEAP). Study participants underwent anthropometric and biochemical measurements. The metabolic syndrome (MetS) prevalence was evaluated according to the National Cholesterol Education Program-Adult Treatment Panel III. Finally, the CV risk was evaluated using three independent algorithms: atherosclerotic cardiovascular disease (ASCVD), European Systematic COronary Risk Evaluation (SCORE), and Cuore risk scores. Mediterranean diet adherence was negatively associated with PRAL and NEAP. Individuals in the higher MDA tertile group had higher HDL cholesterol as well as lower homeostasis model assessment index (HOMA-IR) and fat mass relative to the lowest MDA tertile. However, in the high-MDA tertile group, there was neither a significantly lower MetS prevalence nor CV risk. Instead, both the MetS prevalence and CV risk were higher in individuals in the higher acid PRAL quartile relative to the lower alkaline PRAL quartile. Dietary acid load, especially assessed using PRAL but not MDA, was associated with indices of metabolic and CV prognosis. Thus, DAL assessed by 24-h dietary recalls may represent a better predictor of cardiometabolic health if compared to MDA evaluated using food frequency questionnaires.
Ključne besede: Mediterranean diet, dietary acid load, alkaline diet, acidic diet, metabolic syndrome, cradiovascular risk score
Objavljeno v DiRROS: 19.05.2022; Ogledov: 166; Prenosov: 139
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Early biomarkers of altered renal function and orthostatic intolerance during 10-day bedrest
Grazia Tamma, Annarita Di Mise, Marianna Ranieri, Mariangela Centrone, Maria Venneri, Mariagrazia D'Agostino, Angela Ferrulli, Boštjan Šimunič, Marco Vincenzo Narici, Rado Pišot, Giovanna Valenti, 2022, izvirni znanstveni članek

Povzetek: Exposure to actual or simulated microgravity results in alterations of renal function, fluid redistribution, and bone loss, which is coupled to a rise of urinary calcium excretion. We provided evidence that high calcium delivery to the collecting duct reduces local Aquaporin 2 (AQP2)-mediated water reabsorption under vasopressin action, thus limiting the maximal urinary concentration to reduce calcium saturation. To investigate early renal adaptation into simulated microgravity, we investigated the effects of 10 days of strict bedrest in 10 healthy volunteers. We report here that 10 days of inactivity are associated with a transient, significant decrease (day 5) in vasopressin (copeptin) paralleled by a decrease in AQP2 excretion, consistent with an increased central volume to the heart, resulting in reduced water reabsorption. Moreover, bedrest caused a significant increase in calciuria secondary to bone demineralization paralleled by a decrease in PTH. Urinary osteopontin, a glycoprotein exerting a protective effect on stone formation, was significantly reduced during bedrest. Moreover, a significant increase in adrenomedullin (day 5), a peptide with vasodepressor properties, was observed at day 5, which may contribute to the known reduced orthostatic capacity post-bedrest. We conclude that renal function is altered in simulated microgravity and is associated with an early increase in the risk of stone formation and reduced orthostatic capacity post-bedrest within a few days of inactivity.
Ključne besede: kidney, functions, bed rest, biomarkers, orthostatic intolerance, vasopressin, copeptin, aquaporin-2, adrenomedullin, calcium
Objavljeno v DiRROS: 20.04.2022; Ogledov: 190; Prenosov: 172
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The differences of Slovenian and Italian daily practices experienced in the first wave of covid-19 pandemic
Saša Pišot, Boštjan Šimunič, Ambra Gentile, Antonino Bianco, Gianluca Lo Coco, Rado Pišot, Patrik Drid, Ivana Milovanović, 2022, izvirni znanstveni članek

Povzetek: Background: The COVID-19 pandemic situation with the lockdown of public life caused serious changes in people’s everyday practices. The study evaluates the diferences between Slovenia and Italy in health-related everyday practices induced by the restrictive measures during frst wave of the COVID-19 pandemic. Methods: The cross-sectional cohort study examined changes through an online survey conducted in nine European countries from April 15–28, 2020. The survey included questions from a simple activity inventory questionnaire (SIMPAQ), the European Health Interview Survey, and some other questions. To compare diference in changes between European countries we examined Italy with severe and its neighbour country Slovenia with low incidence and victims of COVID-19 epidemic. 956 valid responses from Italy (N=511; 50% males) and Slovenia (N=445; 26% males) were investigated. Results: During the survey, there was a 4.7-fold higher incidence and 12.1-fold more deaths (per 100,000) in Italy than in Slovenia. Barring periods and measures were similar, the latter more stringent in Italy. We found more changes in Italy than in Slovenia: physical inactivity increased (Italy:+65% vs. Slovenia:+21%; p<0.001), walking time decreased (Italy: -68% vs. Slovenia: -4.4%; p<0.001); physical work increased by 38% in Slovenia (p<0.001), and recreation time decreased by 37% in Italy (p<0.001). Italians reported a decrease in quality of general health, ftness level, psychological well-being, quality of life and care for own health (p<0.001); Slovenians showed a decline in psychological well-being and quality of life (p<0.001) but generally had a higher concern for their own health (p=0.005). In pooled participants, changes in eating habits (meal size and consumption of unhealthy food), age and physical inactivity were positively correlated with increases in body mass, while changes in general well-being and concern for health were negatively correlated. Conclusion: The study shows that the negative impact of COVID -19 measures is greater in Italy where the pandemic COVID -19 was more prevalent than in Slovenia with low prevalence. Additional consideration should be given to the negative impact of COVID-19 measures on some health-related lifestyle variables when implementing further measures to mitigate the COVID-19 pandemic.
Ključne besede: coronavirus pandemic, pandemic measures, home confinement, public health, physical activity, physical inactivity, dietary habits, eating habits, well-being
Objavljeno v DiRROS: 18.02.2022; Ogledov: 250; Prenosov: 183
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Lower-limb muscle contractile properties, explosive power and the subjective response of elite soccer players to the Covid-19 lockdown
Armin Paravlić, Boštjan Šimunič, Saša Pišot, Matej Kleva, Kaja Teraž, Matjaž Vogrin, Uroš Marušič, Rado Pišot, 2022, izvirni znanstveni članek

Povzetek: The present study examined the effects of the lockdown period on basic anthropometric measures, countermovement jumping performance, skeletal muscle contractile properties derived from tensiomyography (TMG), injury incidence, and self-assessed general well-being in elite soccer players. A total of 266 players were assessed before (PRE) and 32 players were reassessed 11 days after (POST) the COVID-19 period. Significant changes in the TMG parameters were observed POST compared to PRE: contraction time (Tc) increased from 6% to 50% in vastus lateralis [VL] (p = 0.009) and biceps femoris [BF] (p < 0.001), respectively; whereas radial displacement (Dm) increased for 19% in BF (p = 0.036) and 17% in VL (p < 0.001), respectively. Jumping performance remained unchanged from PRE to POST In addition, athletes rated the lockdown period as a positive event and felt psychologically better during the lockdown, primarily because they spent more time with family members and friends. Although there were no differences in any of the variables describing lower limb muscle power following the two-month lockdown, the altered contractile properties of the assessed muscles suggest suboptimal conditioning of the football players.
Ključne besede: football, male football, power, explosive power, tensiomyography, coronavirus, covid-19, pandemics, lockdown
Objavljeno v DiRROS: 06.01.2022; Ogledov: 314; Prenosov: 258
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