Lower daily energy expenditure as measured by a respiratory chamber in subjects with spinal cord injury compared with control subjects

Background: This study was designed to determine the effect of chronic spin al cord injury on daily energy expenditure. Objective: We hypothesized that both resting and total energy expenditure w ould be lower in spinal cord-injured (SCI) subjects than in control subject s because of lower sympathetic nervous system activity and reduced levels o f physical activity in SCI subjects. Design: Twenty-four-hour energy expenditure (24-h EE), resting metabolic ra te (RMR), sleeping metabolic rate, spontaneous physical activity, the therm ic effect of food (TEF), and 24-h respiratory quotient were measured by usi ng a respiratory chamber in 10 male SCI subjects (injury ranged from level C6 to L3) and 59 age-matched, noninjured, male control subjects. Results: The 24-h EE was lower in SCI than in control subjects (7824 =/- 30 5 compared with 9941 +/- 188 kJ, P < 0.01). After adjustment for fat-free m ass, fat mass, and age, 24-h EE was still lower (-753 kJ/d, P < 0.01) in SC I than in control subjects. Spontaneous physical activity measured by a rad ar system was also significantly lower (4.6 +/- 0.6% compared with 6.5 +/- 0.3% of time, P < 0.01) in SCI than in control subjects. In absolute value (7347 +/- 268 compared with 9251 +/- 1326 kJ/d, P < 0.01) or after adjustme nt for fat-free mass, fat mass, and age (-678 kJ/d, P < 0.01), RMR was also lower in SCI than in control subjects. TEF was significantly lower in SCI than in control subjects (987 +/- 142 compared with 1544 +/- 213 kJ/d, repr esenting 12.9% and 15.9% of total energy intake, respectively, P < 0.05). T he sleeping metabolic rate and 24-h respiratory quotient did not differ sig nificantly between groups. Conclusions: The 24-h EE was significantly lower in SCI than in control sub jects. This difference can be explained by the lower levels of physical act ivity, and lower RMR and TEF values, in SCI subjects.