RESTING ENERGY-EXPENDITURE AND ENERGY SUBSTRATE UTILIZATION IN CHILDREN WITH DUCHENNE MUSCULAR-DYSTROPHY

The high prevalence of obesity at an early stage of Duchenne muscular dystrophy (DMD) could result not solely from reduced physical activity , but may also involve low resting energy expenditure (REE), abnormal nutrient utilization, or overfeeding. We hypothesized that the dramati c muscle mass loss in DMD should reduce the REE. REE was measured by i ndirect calorimetry in 13 9-13-y-old DMD boys (5 obese, 8 nonobese) an d 9 male age-matched controls. Muscle mass was estimated from 3-d crea tinine excretion in urine. Daily energy intake was estimated from 7-d diet records, In the nonobese DMD group (NODMD) the muscle mass was re duced by 71%, and the REE was 13% lower than in controls (47.5 versus 54.6 kcal . h(-1), p < 0.05). Postabsorptive respiratory quotients app eared higher in both DMD groups than in the controls; however, the dif ference was significant only for the NODMD group (0.88 versus 0.83, p < 0.05). Respiratory quotients were not different between the two DMD groups. Diet records were not contributive in revealing a different di etary behavior between groups. Our results suggest that: 1) muscle mas s loss in DMD is associated with a low REE, 2) low postabsorptive fat utilization might occur at an early stage of the disease, and 3) obesi ty is not associated with an increase in fat utilization in DMD. This study warrants further research to test low REE and low fat utilizatio n as risk factors in developing obesity in DMD.