2.4. Body Composition and Anthropometric Assessments
LUNG
All devices were calibrated and used in accordance with manufacturer instructions and using methods previously described in detail elsewhere [Next, a dual-energy X-ray absorptiometry (DXA; iDXA, General Electric, Boston, MA, USA with enCORE software version 16.10.151, 16 [SP 1]) scan was conducted to provide an estimate of baseline body fat percentage for eligibility purposes and to provide total and segmental body composition values. With the participant lying supine, a set of foam blocks and straps were used to position the participant’s feet perpendicular to the table and their hands in neutral position to each side of their body. When participants were too broad to fit within the designated scan zone of the DXA device, a reflection scan was used to estimate excluded limbs. Previous research has shown the use of reflection scans to introduce minimal error [Anthropometric values were collected with a three-dimensional optical scanner (SS20, Size Stream, scanner version 6.3, software version 5.2.7 for Size Stream Studio). Additionally, the thickness of the abdominal subcutaneous fat layer was assessed via ultrasound (HD3, Clarius, Vancouver, BC, Canada, scanner software version 10.1.1-468+1d2507c276). The application’s Brazilian Butt Lift (BBL) setting, which has a depth of 5 cm, was generally used unless it was determined that a greater depth would be required to assess the entire subcutaneous fat layer. In this case, the Lung setting, which has a depth of 6 cm, was used. The outer edge of the probe was placed approximately 1 cm to the right of the umbilicus and perpendicular to the participant’s torso in order to standardize the images captured. Participants were instructed to relax their arms to their sides and fully exhale before an ultrasound image was captured. The distance from the outer edge of the rectus abdominus to the outer edge of the skin was measured in ImageJ (version 1.53t, National Institutes of Health) by the same assessor with the average of three images used for each timepoint.