A computational predictor of the anaerobic mechanical power outputs from a clinical exercise stress test.

We previously were able to predict the anaerobic mechanical power outputs using features taken from a maximal incremental cardiopulmonary exercise stress test (CPET). Since a standard aerobic exercise stress test (with electrocardiogram and blood pressure measurements) has no gas exchange measurement and is more popular than CPET, our goal, in the current paper, was to investigate whether features taken from a clinical exercise stress test (GXT), either submaximal or maximal, can predict the anaerobic mechanical power outputs to the same level as we found with CPET variables. We have used data taken from young healthy subjects undergoing CPET aerobic test and the Wingate anaerobic test, and developed a computational predictive algorithm, based on greedy heuristic multiple linear regression, which enabled the prediction of the anaerobic mechanical power outputs from a corresponding GXT measures (exercise test time, treadmill speed and slope).

Prediction of the Wingate anaerobic mechanical power outputs from a maximal incremental cardiopulmonary exercise stress test using machine-learning approach.

The Wingate Anaerobic Test (WAnT) is a short-term maximal intensity cycle ergometer test, which provides anaerobic mechanical power output variables. Despite the physiological significance of the variables extracted from the WAnT, the test is very intense, and generally applies for athletes. Our goal, in this paper, was to develop a new approach to predict the anaerobic mechanical power outputs using maximal incremental cardiopulmonary exercise stress test (CPET).

Changes in permeability of the plasma membrane of myoblasts to fluorescent dyes with different molecular masses under sustained uniaxial stretching.

Deep tissue injury (DTI) is a serious pressure ulcer which onsets in skeletal muscle tissues adjacent to weight-bearing bony prominences. Recent literature points at sustained large deformations in muscle tissue, which translate to static stretching of the plasma membrane (PM) at the cell-scale, as the primary cause of accumulated cell death in DTI. It has been specifically suggested that prolonged exposure to large tensional PM strains interferes with normal cellular homeostasis, primarily by affecting transport through the PM which could become more permeable when stretched.

Stretching affects intracellular oxygen levels: three-dimensional multiphysics studies.

Multiphysics modeling is an emerging approach in cellular bioengineering research, used for simulating complex biophysical interactions and their effects on cell viability and function. Our goal in the present study was to integrate cell-specific finite element modeling--which we have developed in previous research to simulate deformation of individual cells subjected to external loading--with oxygen transport in the deformed cells at normoxic and hypoxic environments. We specifically studied individual and combined effects of substrate stretch levels, O₂ concentration in the culture media, and temperature of the culture media on intracellular O₂ levels in cultured myoblasts, in models of two individual cells.

A simple stochastic model to explain the sigmoid nature of the strain-time cellular tolerance curve.

Using animal and tissue-engineered experimental models, we previously found that a decreasing sigmoidal function is adequate for describing the diminishing tolerance of skeletal muscle tissue/cells for static mechanical strains delivered over time. Compressive loads at the tissue scale, which are associated with weight-bearing, appear to stretch the plasma membrane (PM) of cells at the mesoscopic-microscopic scales. The permeability of such stretched PMs may then increase, which could alter the control mechanisms and consequently the homeostasis of the deformed cells.

The effect of compressive deformations on the rate of build-up of oxygen in isolated skeletal muscle cells.

In this study we integrated between confocal-based cell-specific finite element (FE) modeling and Virtual Cell (VC) transport simulations in order to determine trends of relationship between externally applied compressive deformations and build-up rates of oxygen in myoblast cells, and to further test how mild culture temperature drops (~3°C) might affect such trends. Geometries of two different cells were used, and each FE cell model was computationally subjected to large compressive deformations. Build-up of oxygen concentrations within the deformed cell shapes over time were calculated using the VC software.