Computational model of cardiovascular response to centrifugation and lower body cycling exercise

Abstract

Short-radius centrifugation combined with exercise has been suggested as a potential countermeasure against spaceflight deconditioning. Both the long-term and acute physiological responses to such a combination are incompletely understood. We developed and validated a computational model to study the acute cardiovascular response to centrifugation combined with lower body ergometer exercise. The model consisted of 21 compartments, including the upper body, renal, splanchnic, and leg circulation, as well as a four-chamber heart and pulmonary circulation. It also included the effects of gravity gradient and ergometer exercise. Centrifugation and exercise profiles were simulated and compared with experimental data gathered on 12 subjects exposed to a range of gravitational levels (1 and 1.4G measured at the feet) and workload intensities (25–100 W). The model was capable of reproducing cardiovascular changes (within ± 1 SD from the group-averaged behavior) due to both centrifugation and exercise, including dynamic responses during transitions between the different phases of the protocol. The model was then used to simulate the hemodynamic response of hypovolemic subjects (blood volume reduced by 5–15%) subjected to similar gravitational stress and exercise profiles, providing insights into the physiological responses of experimental conditions not tested before. Hypovolemic results are in agreement with the limited available data and the expected responses based on physiological principles, although additional experimental data are warranted to further validate our predictions, especially during the exercise phases. The model captures the cardiovascular response for a range of centrifugation and exercise profiles, and it shows promise in simulating additional conditions where data collection is difficult, expensive, or infeasible. NEW & NOTEWORTHY Artificial gravity combined with exercise is a potential countermeasure for spaceflight deconditioning, but the long-term and acute cardiovascular response to such gravitational stress is still largely unknown. We provide a novel mathematical model of the cardiovascular system that incorporates gravitational stress generated by centrifugation and lower body cycling exercise, and we validate it with experimental measurements from human subjects. Simulations of experimental conditions not used for model development corroborate the model’s predictive capabilities.

Cardiovascular deconditioning during long-term spaceflight through multiscale modeling

“…Given the above difficulties, the computational approach is a recent and promising tool to study the human body's response to microgravity conditions [14][15][16][17][18] , as it can be used to investigate variables and processes which are hard to measure, as well as predict different scenarios and optimal countermeasures. In particular, reduced order modeling seems to be the most appropriate strategy, as it is a reasonable balance between the suitable level of local detail and the overall response (see, among the most recent [19][20][21][22][23] ).…”

Planetary extravehicular activity (EVA) risk mitigation strategies for long-duration space missions

“…The implementation of current (e.g., exercise, nutrition) and future (e.g., centrifugation 29 – 31 ) countermeasures is an important factor to consider. High-intensity interval training combined with artificial gravity may help mitigate cardiovascular deconditioning and promote aerobic fitness, both of which will be especially vital for physically intense planetary EVA 29 , 32 , 33 .…”

Using a Human Circulation Mathematical Model to Simulate the Effects of Hemodialysis and Therapeutic Hypothermia

“…A human circulation model [12,13] was used in our recent study where arterial stiffening was found to be a prime cause of hypertension [14]. A more detailed and calibrated whole body human model [15,16] has been deployed widely, including to predict the consequences of orthostatic stress and exercise [17]. The relative contribution of dialyzer membrane related convection and diffusion have been assessed using steady state hemodynamic modelling [18].…”