engleski

Hemodynamics adjustments and cardiovascular response during variable load exercises in normotensive adults.

The variable load exercise model (e.g., the flywheel, FW) is currently considered to be the most effective method for counteracting muscle atrophy. However, it is still unknown to which extent this type of vigorous exercise actually challenges the cardiovascular system. We investigated the effects of the FW exercise (nHance, Barcelona, Spain) on hemodynamics and cardiovascular adjustments in healthy participants. Thirty participants (age from 20 to 55 y, 37% women) underwent a detailed medical examination and their VO2 peaks were determined. After the completion of the preliminary sessions, the participants were randomly assigned into three different experimental conditions, that is, the FW squat ergometer set at three different (low at 0.025 kg·m2, moderate at 0.050 kg·m2 and high at 0.075 kg·m2) moments of inertia. The hemodynamics response and the heart rate (HR) were continuously monitored (Task force monitor, CNSystems, Graz, Austria) throughout all FW sessions. The blood pressure was assessed via photoplethysmograph using a pneumatic cuff, positioned around the middle finger of the left hand, instructed to be held at the level of the heart throughout the session. The cardio-impedance electrodes were positioned according to the manufacturer’s guidelines to allow non-invasive insight into the hemodynamics throughout the experimental sessions, while the HR was obtained from the bipolar 3-lead electrocardiograph. In parallel, the electromyographic (EMG) activity (TeleMyo 2400T, Noraxon, USA) of the vastus lateralis (VL) muscle was measured throughout the experimental sessions in accordance with the SENIAM guidelines for non-invasive EMG. A robust rise in mean arterial pressure (MAP) was observed across all three moments of inertia compared to baseline readings (p=.001), while MAP head reached the highest values of 179±4 mmHg during high inertial loading. All normalized hemodynamics parameters had a similar response to different FW exercise throughout, while the total peripheral vascular resistance increased by 11% and 22% (for both average and maximal readings, p=.001) during the high inertial loading. Likewise, an increase in HR was noted during all exercise interventions compared to baseline (p=.001), whereas the HR response was 10 bpm higher (p=.001) at high level compared to readings at low and moderate inertial loading. There were no correlations observed between relative increase in MAP and the age of the participants for the low, moderate, or high levels of inertial loadings. Finally, no differences were observed for the VL EMG (EMGRMS) activity (p=.856) among the three levels of inertial loadings. In conclusion, larger loads of inertia during FW exercise seem to impose a substantial burden to the cardiovascular system, whereas the study population age- related differences did not modulate a robust rise in MAP following FW exercise. Thus, we emphasize caution when attempting to prescribe high-load exercise to counter muscle-atrophy.

Variable load exercise ; blood pressure monitoring ; VO2 max.

nije evidentirano