1. Depth of SCUBA diving affects cardiac autonomic nervous systemMarina Vulić, Branislav Milovanovic, Ante Obad, Duška Glavaš, Igor Glavičič, Damir Zubac, Maja Valic, Zoran Valić, 2024, review article Abstract: The present study investigated the influence of SCUBA dives with compressed air at depths of 10 and 20 m on ECG-derived HRV parameters in apparently healthy individuals. We hypothesized that cardiac sympathetic activity (measured by HRV parameters) adapts proportionally to diving depth, and that both time- and frequency-domain parameters are sensitive enough to track changes in cardiac ANS function during diving activities and subsequently during the recovery period. Eleven healthy middle-aged recreational divers (nine men and two women, age 43 ± 8, all nonsmokers) volunteered to participate in the present study. The participants (all open-circuit divers) were equipped with dry suits and ECG Holter devices and were later randomly assigned to dive pairs and depths (10 m vs. 20 m), and each participant served as his or her own control. No interaction effects (diving depth x time epoch) were found for the most commonly used HRV markers. More precisely, in response to two different diving protocols, a significant post hoc effect of time was observed for HR and SDNN, as these parameters transiently decreased during the dives and returned to baseline after ascent (p < 0.001). The ULF, VLF (p < 0.003), TP, and LF parameters decreased significantly during the dives, while HF significantly increased (p < 0.003). SCUBA diving apparently challenges the cardiac ANS, even in healthy individuals. The observed changes reveal possible underwater methods of influencing the parasympathetic activity of the heart depending on the depth of the dive. These results identify autonomic nervous system markers to track the cardiovascular risk related to diving and point to the possibility of tracking cardiovascular system benefits during underwater activities in selected patients
Keywords: autonomic nervous system, diving, parasympathicus, cardiovascular risk
Published in DiRROS: 09.04.2024; Views: 62; Downloads: 27
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2. 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: 1058; Downloads: 1149
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3. 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: 954; Downloads: 881
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