Disclosure: All authors have no conflicts of interest to declare. Funding agencies: This research was funded by the American Diabetes Association (7-08-JF-27), NIH (UL1 RR024153 CTSA), Department of Defense (FA7014-02-2-001) and Cochrane-Weber Foundation at Children's Hospital of Pittsburgh of UPMC (to S Lee).
Changes in fat and skeletal muscle with exercise training in obese adolescents: Comparison of whole-body MRI and dual energy X-ray absorptiometry
Article first published online: 13 JUN 2013
Copyright © 2013 The Obesity Society
Volume 21, Issue 10, pages 2063–2071, October 2013
How to Cite
Lee, S. and Kuk, J. L. (2013), Changes in fat and skeletal muscle with exercise training in obese adolescents: Comparison of whole-body MRI and dual energy X-ray absorptiometry. Obesity, 21: 2063–2071. doi: 10.1002/oby.20448
- Issue published online: 5 OCT 2013
- Article first published online: 13 JUN 2013
- Accepted manuscript online: 20 MAR 2013 02:22AM EST
- Manuscript Accepted: 21 FEB 2013
- Manuscript Revised: 1 FEB 2013
- Manuscript Received: 9 DEC 2012
- American Diabetes Association. Grant Number: 7-08-JF-27
- NIH. Grant Number: UL1 RR024153 CTSA
- Department of Defense. Grant Number: FA7014-02-2-001
- Cochrane-Weber Foundation at Children's Hospital of Pittsburgh of UPMC
We examined skeletal muscle (SM) and fat distribution using whole-body MRI in response to aerobic (AE) versus resistance exercise (RE) training in obese adolescents and whether DXA provides similar estimates of fat and SM change as MRI.
Design and Methods
Thirty-nine obese boys (12-18 years) were randomly assigned to one of three 3-month interventions: AE (n = 14), RE (n = 14), or a control (n = 11).
At baseline, MRI-measured total fat was significantly greater than DXA-measured total fat [△ = 3.1 kg (95% CI: −0.4 to 7.4 kg, P < 0.05)], wherein underestimation by dual energy X-ray absorptiometry (DXA) was greatest in those with the highest total fat. Overall, the changes in total fat were not significantly different between MRI and DXA [△ = −0.4 kg (95% CI: −3.5 to 2.6 kg, P > 0.05)], but DXA tended to overestimate MRI fat losses in those with larger fat losses. MRI-measured SM and DXA-measured lean body mass were significantly correlated, but as expected the absolute values were different at baseline [△ = −28.4 kg (95% CI: −35.4 to −21.3 kg, P < 0.05)]. Further, DXA overestimated MRI gains in SM in those with larger SM gains.
Although DXA and MRI-measured total and regional measures tended to be correlated at baseline and changes with exercise, there were substantial differences in the absolute values derived using DXA versus MRI. Further, there were systemic biases in the estimation between the methods wherein DXA tended to overestimate fat losses and SM gains compared to MRI. Thus, the changes in body composition observed are influenced by the method employed.