Encore 2011 version 13

Participants arrived in the early morning in a fasting state, after not consuming food or drink for at least 8 h. Their height and weight were measured on a calibrated scale (7014 SECA 764, Benson Avenue, CA, United States) in minimal clothing. To determine body composition, the runners were scanned with a whole-body dual-energy x-ray absorptiometry (iDXA) (Encore 2011, Version 13.60, General Electric Company, Madison, WI, United States). Calibration of the iDXA was performed using a phantom model the same day as the tests (Quality Control, QC). The coefficient of variation (CV) was below 0.20% for all QC performed during the study.

DEXA were acquired on a GE Healthcare Lunar enCORE (Madison, WI, USA). Mice were anesthetized with isoflurane and placed stomach down with forelimbs taped perpendicular to the torso. Hind legs were gently pulled to straighten out the hips and adhered to the DEXA platform with the tail centered between the legs. In the DEXA program (GE Healthcare enCORE2011, Version 13.60, Madison, WI, USA), a new patient file was created for each mouse. Height and weight were set at the program minimum of 9.1 inches and 0.1 pounds, respectively. The mouse’s nose was placed slightly below the DEXA crosshairs, with the center line straight down the mouse’s back. Once the DEXA and mouse were in position, the scan parameters were set to 13.4 inches long and 9.1 inches wide, an area which only scans slightly larger than the entire animal. Under these parameters, the tip of the tail was not scanned.