Browsing by Author "Pohl, Andrew J."

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    Stressed volume estimated by finite element analysis predicts the fatigue life of human cortical bone: The role of vascular canals as stress concentrators
    (2021-02) Loundagin, Lindsay L.; Pohl, Andrew J.; Edwards, William Brent
    The fatigue life of cortical bone can vary several orders of magnitude, even in identical loading conditions. A portion of this variability is likely related to intracortical microarchitecture and the role of vascular canals as stress concentrators. The size, spatial distribution, and density of canals determine the peak magnitude and volume of stress concentrations. This study utilized a combination of experimental fatigue testing and image-based finite element (FE) analysis to establish the relationship between the stressed volume (i.e., volume of bone above yield stress) associated with vascular canals and the fatigue life of cortical bone. Thirty-six cortical bone samples were prepared from human femora and tibiae from five donors. Samples were allocated to four loading groups, corresponding to stress ranges of 60, 70, 80, and 90 MPa, then cyclically loaded in zero-compression until fracture. Porosity, canal diameter, canal separation, and canal number for each sample was quantified using X-ray microscopy (XRM) after testing. FE models were created from XRM images and used to calculate the stressed volume. Stressed volume was a good predictor of fatigue life, accounting for 67% of the scatter in fatigue-life measurements. An increase in stressed volume was most strongly associated with higher levels of intracortical porosity and larger canal diameters. The findings from this study suggest that a large portion of the fatigue-life variance of cortical bone in zero-compression is driven by intracortical microarchitecture, and that fatigue failure may be predicted by quantifying the stress concentrations associated with vascular canals.
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    The online delivery of exercise oncology classes supported with health coaching: a parallel pilot randomized controlled trial
    (2023-05-12) Eisele, Maximilian; Pohl, Andrew J.; McDonough, Meghan H.; McNeely, Margaret L.; Ester, Manuel; Daun, Julia T.; Twomey, Rosie; Culos-Reed, S. N.
    Abstract Purpose The primary objective was to investigate the feasibility of a synchronous, online-delivered, group-based, supervised, exercise oncology maintenance program supported with health coaching. Methods Participants had previously completed a 12-week group-based exercise program. All participants received synchronous online delivered exercise maintenance classes, and half were block randomized to receive additional weekly health coaching calls. A class attendance rate of ≥ 70%, a health coaching completion rate of ≥ 80%, and an assessment completion rate of ≥ 70% were set as markers of feasibility. Additionally, recruitment rate, safety, and fidelity of the classes and health coaching calls were reported. Post-intervention interviews were performed to further understand the quantitative feasibility data. Two waves were conducted — as a result of initial COVID-19 delays, the first wave was 8 weeks long, and the second wave was 12 weeks long, as intended. Results Forty participants (n8WK = 25; n12WK = 15) enrolled in the study with 19 randomized to the health coaching group and 21 to the exercise only group. The recruitment rate (42.6%), attrition (2.5%), safety (no adverse events), and feasibility were confirmed for health coaching attendance (97%), health coaching fidelity (96.7%), class attendance (91.2%), class fidelity (92.6%), and assessment completion (questionnaire = 98.8%; physical functioning = 97.5%; Garmin wear-time = 83.4%). Interviews highlighted that convenience contributed to participant attendance, while the diminished ability to connect with other participants was voiced as a drawback compared to in-person delivery. Conclusion The synchronous online delivery and assessment of an exercise oncology maintenance class with health coaching support was feasible for individuals living with and beyond cancer. Providing feasible, safe, and effective exercise online to individuals living with cancer may support increased accessibility. For example, online may provide an accessible alternative for those living in rural/remote locations as well as for those who may be immunocompromised and cannot attend in-person classes. Health coaching may additionally support individuals’ behavior change to a healthier lifestyle. Trial registration The trial was retrospectively registered (NCT04751305) due to the rapidly evolving COVID-19 situation that precipitated the rapid switch to online programming.