1. Retinal venular vessel diameters are smaller during ten days of bed restAdam Salon, Göktuğ Mert Çiftci, Damir Zubac, Boštjan Šimunič, Rado Pišot, Marco Vicenzo Narici, Per Morten Fredriksen, Benedicta Ngwenchi Nkeh-Chungag, Harald Sourij, Nandu Goswami, 2023, original scientific article Abstract: Older individuals experience cardiovascular dysfunction during extended bedridden hospital or care home stays. Bed rest is also used as a model to simulate accelerated vascular deconditioning occurring during spacefight. This study investigates changes in retinal microcirculation during a tenday bed rest protocol. Ten healthy young males (22.9± 4.7 years; body mass index: 23.6± 2.5 kg·m–2) participated in a strictly controlled repeated-measures bed rest study lasting ten days. High-resolution images were obtained using a hand-held fundus camera at baseline, daily during the 10 days of bed rest, and 1 day after re-ambulation. Retinal vessel analysis was performed using a semi-automated software system to obtain metrics for retinal arteriolar and venular diameters, central retinal artery equivalent and central retinal vein equivalent, respectively. Data analysis employed a mixed linear model. At the end of the bed rest period, a signifcant decrease in retinal venular diameter was observed, indicated by a signifcantly lower central retinal vein equivalent (from 226.1 µm, CI 8.90, to 211.4 µm, CI 8.28, p= .026), while no signifcant changes in central retinal artery equivalent were noted. Prolonged bed rest confnement resulted in a signifcant (up to 6.5%) reduction in retinal venular diameter. These fndings suggest that the changes in retinal venular diameter during bedrest may be attributed to plasma volume losses and refect overall (cardio)-vascular deconditioning. Keywords: eyes, retinal venular vessel, venske žile, bed rest, gibalna neaktivnost Published in DiRROS: 23.11.2023; Views: 910; Downloads: 268
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2. Effects of meditation on cardiovascular and muscular responses in patients during cardiac rehabilitation : a randomized pilot studyMaximilian E. Rudlof, Boštjan Šimunič, Bianca Steuber, Till O. Bartel, Ruslan Neshev, Petra Mächler, Andreas Dorr, Rainer Picha, Karin Schimd-Zalaudek, Nandu Goswami, 2022, original scientific article Abstract: Background: Cardiovascular diseases are the world’s number one cause of death, with exceeding psychosocial stress load being considered a major risk factor. A stress management technique that has repeatedly shown positive effects on the cardiovascular system is the Transcendental Meditation (TM) technique. The present pilot study aimed to investigate the potential effect of TM on the recovery of cardiac patients. Objectives: We hypothesized that practicing TM in patients undergoing a 4-week cardiac rehabilitation program augments the recovery of cardiovascular parameters and reduces skeletal muscle tone after rehabilitation. Methods: Twenty cardiac patients were recruited and randomly assigned to either the control or the TM group. Cardiovascular parameters were assessed with the Task Force Monitor (TFM) and skeletal muscle contractile properties by Tensiomyography during a sit-stand test, performed at the beginning and end of a 4-week in-patient rehabilitation program. Results: Systolic blood pressure (SBP) was significantly lower after 4 weeks of cardiac rehabilitation, while the RR-interval (RRI) significantly increased. At the skeletal muscle level, the contraction time and maximal displacement increased, though only in the gastrocnemius medialis and biceps femoris muscles and not in vastus lateralis. Group interactions were not observed for hemodynamic parameters nor for muscle contractile properties. Discussion: Although significant improvements in hemodynamic and muscular parameters were observed after 4 weeks of rehabilitation, we could not provide evidence that TM improved rehabilitation after 4 weeks. TM may unfold its effects on the cardiovascular system in the longer term. Hence, future studies should comprise a long-term follow-up. Keywords: cardiovascular diseases, psychosocial stress, transcendental meditation, cardiac rehabilitation, tensiomyography Published in DiRROS: 28.10.2022; Views: 587; Downloads: 371
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3. Quantification of the link between timed up-and-go test subtasks and contractile muscle propertiesAndreas Ziegl, Dieter Hayn, Peter Kastner, Ester Fabiani, Boštjan Šimunič, Kerstin Löffler, Lisa Weidinger, Bianca Brix, Nandu Goswami, Günter Schreier, 2021, original scientific article Abstract: 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. Keywords: timed up-and-go test, tensiomyography, biomedical engineering, biomedical sensors, health Published in DiRROS: 18.10.2021; Views: 963; Downloads: 878
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4. A randomized crossover trial on the acute cardiovascular demands during flywheel exerciseDamir Zubac, Vladimir Ivančev, Zoran Valić, Rado Pišot, Cécil J. W. Meulenberg, Irhad Trozic, Nandu Goswami, Boštjan Šimunič, 2021, original scientific article Abstract: 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. Keywords: yo-yo exercise, oxygen uptake, muscles loading, blood pressure, krvni tlak, flow mediate dilation Published in DiRROS: 05.07.2021; Views: 1253; Downloads: 1350
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5. Independent infuence of age on heart rate recovery after flywheel exercise in trained men and womenDamir Zubac, Nandu Goswami, Vladimir Ivančev, Zoran Valić, Boštjan Šimunič, 2021, original scientific article Abstract: 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. Keywords: training, exercise, Yo-Yo exercise, flywheel, heart rate variability, total peripheral conductance, oxygen uptake kinetics Published in DiRROS: 11.06.2021; Views: 1153; Downloads: 1024
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