Optimal control model response using first-principle model to two different workload (blue) demands, approximately square waves of 0–50 W (Lower) and 100–150 W (Upper): For each data set (using subject 2’s data), a physiological model with optimal controller is simulated with workload as input (blue) and HR (black) as output, and compared with collected HR data (red). Simulations of blood pressure (Pas, purple) and tissue oxygen saturation ([O2] Respiration was natural (perhaps not managed).
The change in the tradeoff as workload increases is consistent with what we observed using the static model. At low workload and low HR, the main tradeoff is metabolic because both Pas and HR are at safe and sustainable levels. High HR and thus high [O2]2), maintains aerobic muscle metabolism, extending the potential duration of exercise while preserving carbohydrate resources for the brain. At higher workloads, this strategy would produce unsustainably high and potentially damaging Pas and possibly HR, so the optimal controller penalizes these factors more, at the price of reduced [O2]T. HRV (slow time scale) in Fig. 1 (and Pas in Fig. 4) decreases with increasing workload because of the changing tradeoffs between metabolic overhead and Pas, ?O2, and H as their means increase. These explanations in HRV derived from the dynamic aerobic model are richer and more complete but due to the same tradeoffs as in the simpler static model.
Significantly, whilst the mathematics and you can anatomy called for try seemingly basic while the ensuing cause is actually intuitively obvious and mechanistic, it nonetheless highlight the fresh rigor and scalability regarding the means. The fresh new convenience of brand new black colored-field ties in step one and you will Fig. step 1 helps establish causal dating between variables and you may suggests mental mechanisms in order to model in more detail, and you will highlights have from the signals that are not modeled (we.e., i have not told me the high frequency of your indicators in the reasonable watts into the Fig. 1, sensed in the next parts). The difficult homeostatic tradeoffs in addition to actuator results of Hr, venting, and you may vasodilation had been as part of the physiology model in two–5 nevertheless neuroendocrine implementation details were not. Plus, this new impression regarding mental autoregulatory saturation was integrated, however the details of execution weren’t. Nevertheless, this method allows medically actionable grounds which do not count toward defectively understood mechanisms peripheral on parts being modeled, while offering a structure having systematically refining such as patterns using good comparable (however, presumably greatly harder) combination of black- and you may grey-container patterns and you may physiology. Once more, if the the fresh new tradeoffs perhaps not sensed here are found to be high, they may be extra individually as most limits is recognized and you may selection recomputed. Next, tradeoffs may well changes while the organ assistance falter, when such designs is extended to help you problem states.
High-Volume HRV.
The fresh large-regularity movement in Time that are instance highest from the lowest indicate workloads and reasonable Hr can’t be explained from the easy fits otherwise models significantly more than, and therefore more signals and you can mechanisms should be incorporated that may become causally associated with it setting. Figs. 5 and you may six highlight breathing while the a factor in much of the fresh new large-regularity HRV. Fig. 5A shows Hr (red) throughout the sheer respiration at peace, to the optimum fixed complement H = h(V) = b·V + c, in which V (blue) are counted ventilation https://www.datingranking.net/fr/sites-de-rencontre-musulmans disperse rates (inhalation and you may exhalation) from the mouthpiece. The new fixed linear fit can be used to measure new products of V (blue) within the Fig. 5A to visualize an educated complement so you can Hr (red) and its particular mistake, revealed in the Table dos. One Hr and venting match very well from inside the volume are consistent towards observation one to less than certain standards, desire are followed closely by an acceleration of Hour, and conclusion because of the a great deceleration, an event called breathing sinus arrhythmia (RSA) (16, 40 ? ? ? ? ? –46). However, since the ventilation and Hours was each other from neuroendocrine control, this fit (we.elizabeth., correlation) by itself does not highly recommend a certain mechanistic factor of the ensuing ventilation–Hour relationship otherwise HRV.
