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31.
Analiza učinkovitosti športnic med menstrualnim ciklom : končno raziskovalno poročilo
Damir Zubac, Boštjan Šimunič, 2021, končno poročilo o rezultatih raziskav

Objavljeno v DiRROS: 17.11.2021; Ogledov: 703; Prenosov: 224
.pdf Celotno besedilo (252,02 KB)

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33.
Validacija markerja mišične kakovosti : končno poročilo o rezultatih raziskave
Boštjan Šimunič, Armin Paravlić, 2021, končno poročilo o rezultatih raziskav

Ključne besede: mišice, mišična masa, mišična kakovost, mišična moč, merjenje, biomarkerji
Objavljeno v DiRROS: 12.11.2021; Ogledov: 703; Prenosov: 232
.pdf Celotno besedilo (268,48 KB)

34.
Quantification of the link between timed up-and-go test subtasks and contractile muscle properties
Andreas Ziegl, Dieter Hayn, Peter Kastner, Ester Fabiani, Boštjan Šimunič, Kerstin Löffler, Lisa Weidinger, Bianca Brix, Nandu Goswami, Günter Schreier, 2021, izvirni znanstveni članek

Povzetek: Frailty and falls are a major public health problem in older adults. Muscle weakness of the lower and upper extremities are risk factors for any, as well as recurrent falls including injuries and fractures. While the Timed Up-and-Go (TUG) test is often used to identify frail members and fallers, tensiomyography (TMG) can be used as a non-invasive tool to assess the function of skeletal muscles. In a clinical study, we evaluated the correlation between the TMG parameters of the skeletal muscle contraction of 23 elderly participants (22 f, age 86.74 % 7.88) and distance-based TUG test subtask times. TUG tests were recorded with an ultrasonic-based device. The sit-up and walking phases were significantly correlated to the contraction and delay time of the muscle vastus medialis (% = 0.55%0.80, p < 0.01). In addition, the delay time of the muscles vastus medialis (% = 0.45, p = 0.03) and gastrocnemius medialis (% = %0.44, p = 0.04) correlated to the sit-down phase. The maximal radial displacements of the biceps femoris showed significant correlations with the walk-forward times (% = %0.47, p = 0.021) and back (% = %0.43, p = 0.04). The association of TUG subtasks to muscle contractile parameters, therefore, could be utilized as a measure to improve the monitoring of elderly people%s physical ability in general and during rehabilitation after a fall in particular. TUG test subtask measurements may be used as a proxy to monitor muscle properties in rehabilitation after long hospital stays and injuries or for fall prevention.
Ključne besede: timed up-and-go test, tensiomyography, biomedical engineering, biomedical sensors, health
Objavljeno v DiRROS: 18.10.2021; Ogledov: 776; Prenosov: 690
.pdf Celotno besedilo (1,34 MB)
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35.
The aging muscle in experimental bed rest : ǂa ǂsystematic review and meta-analysis
Filippo Giorgio Di Girolamo, Nicola Fiotti, Zoran Milanović, Roberta Situlin, Filippo Mearelli, Pierandrea Vinci, Boštjan Šimunič, Rado Pišot, Marco Vicenzo Narici, Gianni Biolo, 2021, pregledni znanstveni članek

Povzetek: Background: Maintaining skeletal muscle mass and function in aging is crucial for preserving the quality of life and health. An experimental bed rest (BR) protocol is a suitable model to explore muscle decline on aging during inactivity. Objective: The purpose of this systematic review and meta-analysis was, therefore, to carry out an up-to-date evaluation of bed rest, with a specific focus on the magnitude of effects on muscle mass, strength, power, and functional capacity changes as well as the mechanisms, molecules, and pathways involved in muscle decay. Design: This was a systematic review and meta-analysis study. Data sources: We used PubMed, Medline; Web of Science, Google Scholar, and the Cochrane library, all of which were searched prior to April 23, 2020. A manual search was performed to cover bed rest experimental protocols using the following key terms, either singly or in combination: %Elderly Bed rest,% %Older Bed rest,% %Old Bed rest,% %Aging Bed rest,% %Aging Bed rest,% %Bed-rest,% and %Bedrest%. Eligibility criteria for selecting studies: The inclusion criteria were divided into four sections: type of study, participants, interventions, and outcome measures. The primary outcome measures were: body mass index, fat mass, fat-free mass, leg lean mass, cross-sectional area, knee extension power, cytokine pattern, IGF signaling biomarkers, FOXO signaling biomarkers, mitochondrial modulation biomarkers, and muscle protein kinetics biomarkers. Results: A total of 25 studies were included in the qualitative synthesis, while 17 of them were included in the meta-analysis. In total, 118 healthy elderly volunteers underwent 5-, 7-, 10-, or 14-days of BR and provided a brief sketch on the possible mechanisms involved. In the very early phase of BR, important changes occurred in the skeletal muscle, with significant loss of performance associated with a lesser grade reduction of the total body and muscle mass. Meta-analysis of the effect of bed rest on total body mass was determined to be small but statistically significant (ES = %0.45, 95% CI: %0.72 to %0.19, P < 0.001). Moderate, statistically significant effects were observed for total lean body mass (ES = %0.67, 95% CI: %0.95 to %0.40, P < 0.001) after bed rest intervention. Overall, total lean body mass was decreased by 1.5 kg, while there was no relationship between bed rest duration and outcomes (Z = 0.423, p = 672). The meta-analyzed effect showed that bed rest produced large, statistically significant, effects (ES = %1.06, 95% CI: %1.37 to %0.75, P < 0.001) in terms of the knee extension power. Knee extension power was decreased by 14.65 N/s. In contrast, to other measures, meta-regression showed a significant relationship between bed rest duration and knee extension power (Z = 4.219, p < 0.001). Moderate, statistically significant, effects were observed after bed rest intervention for leg muscle mass in both old (ES = %0.68, 95% CI: %0.96 to %0.40, P < 0.001) and young (ES = %0.51, 95% CI: %0.80 to %0.22, P < 0.001) adults. However, the magnitude of change was higher in older (MD = %0.86 kg) compared to younger (MD = %0.24 kg) adults. Conclusion: Experimental BR is a suitable model to explore the detrimental effects of inactivity in young adults, old adults, and hospitalized people. Changes in muscle mass and function are the two most investigated variables, and they allow for a consistent trend in the BR-induced changes. Mechanisms underlying the greater loss of muscle mass and function in aging, following inactivity, need to be thoroughly investigated.
Ključne besede: bed rest, aging, muscles, muscle physiopathology, muscle function
Objavljeno v DiRROS: 26.08.2021; Ogledov: 1654; Prenosov: 871
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36.
A randomized crossover trial on the acute cardiovascular demands during flywheel exercise
Damir Zubac, Vladimir Ivančev, Zoran Valić, Rado Pišot, Cécil J. W. Meulenberg, Irhad Trozic, Nandu Goswami, Boštjan Šimunič, 2021, izvirni znanstveni članek

Povzetek: In a randomized crossover trial, we examined whether age plays a role in the mean arterial pressure (MAP) response during a vigorous flywheel exercise of varying load. We hypothesized that the magnitude of increase in the MAP during the flywheel exercise would increase in proportion to advancing age, thereby imposing a significant challenge to the cardiovascular system. A total of 30 participants of both sexes (age range from 20%55 y, 37% women) underwent a detailed medical examination, and their maximal oxygen uptake was determined. They performed a squat exercise (2 sets % 7 repetitions) on a flywheel ergometer at three randomly assigned moments of inertia set at 0.025, 0.05, and 0.075 kg m2, while the cardiovascular response was continuously recorded via a Task force monitor. Compared to the resting values, robust rises in the MAP were observed during all three flywheel loads, reaching the highest value of 179 % 4 mmHg (p = 0.001) during the highest load. In parallel, the cardiac index (cardiac output normalized by the body surface area) was two-fold greater during all the flywheel loads compared to rest, and at a high load, exclusively, the total peripheral resistance increased by 11% (p = 0.001). The rise in heart rate compensated for a load-dependent drop in the stroke index (stroke volume normalized by the body surface area). In our study population, no correlations were observed between the relative increase in the MAP and the participants% age for the three flywheel loads. The present findings suggest that the larger moments of inertia impose a substantial burden to the cardiovascular system, without apparent associated age-differences of the relative magnitude of MAP rise throughout the exercise.
Ključne besede: yo-yo exercise, oxygen uptake, muscles loading, blood pressure, krvni tlak, flow mediate dilation
Objavljeno v DiRROS: 05.07.2021; Ogledov: 1039; Prenosov: 1099
.pdf Celotno besedilo (1,85 MB)
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37.
Neuromuscular junction instability and altered intracellular calcium handling as early determinants of force loss during unloading in humans
Elena Monti, Carlo Reggiani, Martino V. Franchi, Luana Toniolo, Marco Sandri, Andrea Armani, Sandra Zampieri, Boštjan Šimunič, Rado Pišot, Marco Vicenzo Narici, 2021, izvirni znanstveni članek

Povzetek: Unloading induces rapid skeletal muscle atrophy and functional decline. Importantly, force is lost at a much higher rate than muscle mass. We aimed to investigate the early determinants of the disproportionate loss of force compared to that of muscle mass in response to unloading. Ten young participants underwent 10 days of bed rest (BR). At baseline (BR0) and at 10 days (BR10), quadriceps femoris (QF) volume (VOL) and isometric maximum voluntary contraction (MVC) were assessed. At BR0 and BR10 blood samples and biopsies of vastus lateralis (VL) muscle were collected. Neuromuscular junction (NMJ) stability and myofibre innervation status were assessed, together with single fibre mechanical properties and sarcoplasmic reticulum (SR) calcium handling. From BR0 to BR10, QFVOL and MVC decreased by 5.2% (P = 0.003) and 14.3% (P < 0.001), respectively. Initial and partial denervation was detected from increased neural cell adhesion molecule (NCAM)-positive myofibres at BR10 compared with BR0 (+3.4%, P = 0.016). NMJ instability was further inferred from increased C-terminal agrin fragment concentration in serum (+19.2% at BR10, P = 0.031). Fast fibre cross-sectional area (CSA) showed a trend to decrease by 15% (P = 0.055) at BR10, while single fibre maximal tension (force/CSA) was unchanged. However, at BR10 SR Ca2+ release in response to caffeine decreased by 35.1% (P < 0.002) and 30.2% (P < 0.001) in fast and slow fibres, respectively, pointing to an impaired excitation%contraction coupling. These findings support the view that the early onset of NMJ instability and impairment in SR function are eligible mechanisms contributing to the greater decline in muscle force than in muscle size during unloading.
Ključne besede: Ca2+ dynamics, muscle atrophy, neuromuscular junction instability, sarcoplasmic reticulum, single fibre atrophy, single fibre contractile impairment, unloading
Objavljeno v DiRROS: 16.06.2021; Ogledov: 1066; Prenosov: 1056
.pdf Celotno besedilo (3,39 MB)
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38.
Independent infuence of age on heart rate recovery after flywheel exercise in trained men and women
Damir Zubac, Nandu Goswami, Vladimir Ivančev, Zoran Valić, Boštjan Šimunič, 2021, izvirni znanstveni članek

Povzetek: The present study examined whether differences in the heart rate recovery following flywheel exercise cessation were associated with differences in maximal oxygen uptake (VO2 max.), age and sex in trained adults. Eleven men (age range 22-49 years, VO2 max.=43.6 +/- 7.6 mL kg min -1) and ten women (age range 20-53 years, VO2 max.=38.0 +/- 5.7 mL kg min%1) were randomly assigned to complete a squat-exercise on the flywheel ergometer set at three different moments of inertia, while their cardiovascular responses were continuously monitored. During the flywheel exercise the mean arterial pressure rose by ~35 to 40% (p=.001), and the increment was more robust in men than women. The cardiac index was two-fold greater across both sexes compared to the baseline (p=.001), while the rise in heart rate (~144 bpm) was more pronounced in women to compensate for their load-dependent stroke index decline (p=.001). The load-independent time-course changes in heart rate recovery markers were comparable between the sexes. When these indicators were pooled, a stepwise regression revealed age as the only relevant predictor of both fast and slow components of the heart rate recovery (~30 of the shared variance explained, p=.014). The present data suggest that the heart rate recovery declines with age, irrespective of sex, or well-preserved cardiorespiratory fitness in moderately-trained adults.
Ključne besede: training, exercise, Yo-Yo exercise, flywheel, heart rate variability, total peripheral conductance, oxygen uptake kinetics
Objavljeno v DiRROS: 11.06.2021; Ogledov: 941; Prenosov: 866
.pdf Celotno besedilo (1,64 MB)
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39.
Globally altered sleep patterns and physical activity levels by confinement in 5056 individuals : ECLB COVID-19 international online survey
Khaled Trabelsi, Achraf Ammar, Liwa Masmoudi, Omar Boukhris, Hamdi Chtourou, Bassem Bouaziz, Michael Brach, Boštjan Šimunič, Rado Pišot, Saša Pišot, 2021, izvirni znanstveni članek

Povzetek: Symptoms of psychological distress and disorder have been widely reported in people under quarantine during the COVID-19 pandemic; in addition to severe disruption of peoples% daily activity and sleep patterns. This study investigates the association between physical-activity levels and sleep patterns in quarantined individuals. An international Google online survey was launched in April 6th, 2020 for 12-weeks. Forty-one research organizations from Europe, North-Africa, Western-Asia, and the Americas promoted the survey through their networks to the general society, which was made available in 14 languages. The survey was presented in a differential format with questions related to responses %before% and %during% the confinement period. Participants responded to the Pittsburgh Sleep Quality Index (PSQI) questionnaire and the short form of the International Physical Activity Questionnaire. 5056 replies (59.4% female), from Europe (46.4%), Western-Asia (25.4%), America (14.8%) and North-Africa (13.3%) were analysed. The COVID-19 home confinement led to impaired sleep quality, as evidenced by the increase in the global PSQI score (4.37 % 2.71 before home confinement vs. 5.32 % 3.23 during home confinement) (p < 0.001). The frequency of individuals experiencing a good sleep decreased from 61% (n = 3063) before home confinement to 48% (n = 2405) during home confinement with highly active individuals experienced better sleep quality (p < 0.001) in both conditions. Time spent engaged in all physical-activity and the metabolic equivalent of task in each physical-activity category (i.e., vigorous, moderate, walking) decreased significantly during COVID-19 home confinement (p < 0.001). The number of hours of daily-sitting increased by ~2 hours/days during home confinement (p < 0.001). COVID-19 home confinement resulted in significantly negative alterations in sleep patterns and physical-activity levels. To maintain health during home confinement, physical-activity promotion and sleep hygiene education and support are strongly warranted.
Ključne besede: coronavirus, COVID-19, pandemic, public health, restrictions, isolation, home confinement, psychosocial health, sleep, sedentary lifestyle, physical activities, lifestyle, behaviours
Objavljeno v DiRROS: 24.03.2021; Ogledov: 10035; Prenosov: 775
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40.
Absence of an aging-related increase in fibre type grouping in athletes and non-athletes
Guy A. M. Messa, Mathew Piasecki, Joern Rittweger, Jamie McPhee, Erika Koltai, Zsolt Radak, Boštjan Šimunič, Ari Heinonen, Harri Suominen, Marko T. Korhonen, Hans Degens, 2020, izvirni znanstveni članek

Povzetek: The ageing-related loss of muscle mass is thought to be partly attributable to motor neuron loss and motor unit remodelling that result in fibre type grouping. We examined fibre type grouping in 19- to 85-year-old athletes and non-athletes and evaluated to which extent any observed grouping is explained by the fibre type composition of the muscle. Since regular physical activity may stimulate reinnervation, we hypothesised that fibre groups are larger in master athletes than in age-matched non-athletes. Fibre type grouping was assessed in m. vastus lateralis biopsies from 22 young (19-27 years) and 35 healthy older (66-82 years) non-athletes, and 14 young (20-29 years), 51 middle-aged (38%65 years) and 31 older (66-85 years) athletes. An "enclosed fibre" was any muscle fibre of a particular type surrounded by fibres of the same type only. A fibre type group was defined as a group of fibres with at least one enclosed fibre. Only type II fibre cross-sectional area (FCSA) showed an age-related decline that was greater in athletes (p < 0.001) than in non-athletes (p = 0.012). There was no significant age-related effect on fibre group size or fibre group number in athletes or non-athletes, and the observed grouping was similar to that expected from the fibre type composition. At face value these observations do 1) neither show evidence for an age-related loss and remodelling of motor units nor 2) improved reinnervation with regular physical activity, but 3) histological examination may not reveal the full extent of ageing-related motor unit remodelling.
Ključne besede: aging, denervation, fibre type, reinnervation, vastus lateralis
Objavljeno v DiRROS: 24.03.2021; Ogledov: 1032; Prenosov: 789
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