In Vivo 3D Analysis of Thoracic Kinematics : Changes in Size and Shape During Breathing and Their Implications for Respiratory Function in Recent Humans and Fossil Hominins

The human ribcage expands and contracts during respiration as a result of the interaction between the morphology of the ribs, the costo-vertebral articulations and respiratory muscles. Variations in these factors are said to produce differences in the kinematics of the upper thorax and the lower thorax, but the extent and nature of any such differences and their functional implications have not yet been quantified. Applying geometric morphometrics we measured 402 three-dimensional (3D) landmarks and semilandmarks of 3D models built from computed tomographic scans of thoraces of 20 healthy adult subjects in maximal forced inspiration (FI) and expiration (FE). We addressed the hypothesis that upper and lower parts of the ribcage differ in kinematics and compared different models of functional compartmentalization. During inspiration the thorax superior to the level of the sixth ribs undergoes antero-posterior expansion that differs significantly from the medio-lateral expansion characteristic of the thorax below this level. This supports previous suggestions for dividing the thorax into a pulmonary and diaphragmatic part. While both compartments differed significantly in mean size and shape during FE and FI the size changes in the lower compartment were significantly larger. Additionally, for the same degree of kinematic shape change, the pulmonary thorax changes less in size than the diaphragmatic thorax. Therefore, variations in the form and function of the diaphragmatic thorax will have a strong impact on respiratory function. This has important implications for interpreting differences in thorax shape in terms of respiratory functional differences within and among recent humans and fossil hominins. Anat Rec, 300:255–264, 2017

Pre-Exposure and Recovery in Activity-Based Anorexia

Activity-based anorexia (ABA) occurs when there is limited access to food and an opportunity to engage in high levels of physical activity. While the ABA effect is well established, the distinct functions of exercise and food restriction in maintaining ABA have not been determined. The current study examined the effect of pre-exposure to a restricted feeding schedule and pre-exposure to a running wheel on the incidence of ABA in 36 rats. Access to food and the running wheel was also varied in the recovery phase of the study in order to establish the effect of these variables on recovery from ABA. Three adaptation conditions (pre-exposed to food restriction, pre-exposed to wheel access and non-exposed) and two recovery conditions (wheel access and food restriction recovery) defined the six groups in the current study. Significant differences in the incidence of ABA between the adaptation conditions, and different patterns of recovery from ABA between the two recovery conditions, as well as evidence of an interaction between adaptation and recovery were revealed. The results of the current study aid in understanding the distinct functions of food restriction and exercise in maintaining and recovering from ABA and have possible implications for the treatment of people diagnosed with some types of anorexia nervosa

A three-Dimensional Human Trunk Model for the Analysis of Respiratory Mechanics

Over the past decade, road safety research and impact biomechanics have strongly stimulated the development of anatomical human numerical models using the finite element (FE) approach. The good accuracy of these models, in terms of geometric definition and mechanical response, should now find new areas of application. We focus here on the use of such a model to investigate its potential when studying respiratory mechanics. The human body FE model used in this study was derived from the RADIOSS® HUMOS model. Modifications first concerned the integration and interfacing of a user-controlled respiratory muscular system including intercostal muscles, scalene muscles, the sternocleidomastoid muscle, and the diaphragm and abdominal wall muscles. Volumetric and pressure measurement procedures for the lungs and both the thoracic and abdominal chambers were also implemented. Validation of the respiratory module was assessed by comparing a simulated maximum inspiration maneuver to volunteer studies in the literature. Validation parameters included lung volume changes, rib rotations, diaphragm shape and vertical deflexion, and intra-abdominal pressure variation. The HUMOS model, initially dedicated to road safety research, could be turned into a promising, realistic 3D model of respiration with only minor modifications. Internal abdominal pressure, respiratory mechanics, diaphragm, numerical mode