Effect of adjusting pulse durations of functional electrical stimulation cycling on energy expenditure and fatigue after spinal cord injury.

The purpose of the current study was to determine the effects of three different pulse durations (200, 350, and 500 microseconds [P200, P350, and P500, respectively]) on oxygen uptake (VO2), cycling performance, and energy expenditure (EE) percentage of fatigue of the knee extensor muscle group immediately and 48 to 72 h after cycling in persons with spinal cord injury (SCI). A convenience sample of 10 individuals with motor complete SCI participated in a repeated-measures design using a functional electrical stimulation (FES) cycle ergometer over a 3 wk period. There was no difference among the three FES protocols on relative VO2 or cycling EE. Delta EE between exercise and rest was 42% greater in both P500 and P350 compared with P200 (p = 0.07), whereas recovery VO2 was 23% greater in P350 compared with P200 (p = 0.03). There was no difference in the outcomes of the three pulse durations on muscle fatigue. Knee extensor torque significantly decreased immediately after (p < 0.001) and 48 to 72 h after (p < 0.001) FES leg cycling. Lengthening pulse duration did not affect submaximal or relative VO2 or EE, total EE, and time to fatigue. Greater recovery VO2 and delta EE were noted in P350 and P500 compared with P200. An acute bout of FES leg cycling resulted in torque reduction that did not fully recover 48 to 72 h after cycling.

Femoral bone marrow adiposity and cortical bone cross-sectional areas in men with motor complete spinal cord injury.

OBJECTIVES: To (1) quantify yellow and red bone marrow (BM) and cortical bone cross-sectional areas (CSAs) of the femur in persons with motor complete spinal cord injury (SCI) compared with healthy able-bodied control subjects and (2) determine the relationships between yellow and red BM, cortical CSAs, and thigh composition and measurements from dual-energy x-ray absorptiometry in men with complete SCI. DESIGN: Cross-sectional. SETTINGS: Clinical hospital and academic settings. METHODS: Eight persons with motor complete SCI and 6 age-matched healthy control subjects underwent magnetic resonance imaging of both thighs to measure BM adiposity (BMA) and cortical CSA followed by whole-body dual-energy x-ray absorptiometry to measure bone mineral density and body composition for the SCI group. RESULTS: Cortical bone CSA adjusted to total subperiosteal bone CSA was 1.5-2 times lower in men with SCI compared with able-bodied control subjects across the femoral length (P =.003). Yellow BMA CSA was 2-3 times greater in men with SCI compared with able-bodied control subjects (P < .0001). Opposite relationships were found between the yellow BMA CSA and cortical bone CSAs in men with SCI (negative association) and able-bodied control subjects (positive association). Yellow BMA was negatively associated with bone mineral density and bone mineral content and with skeletal muscle CSA and fat-free mass (P <.05) in men with SCI. Finally, yellow BMA was positively related to thigh subcutaneous adipose tissue. CONCLUSIONS: After SCI, cortical bone CSA becomes thinner and is associated with greater accumulation of yellow BMA. Yellow BMA is associated with changes in bone CSA and bone mass, as well as increased fat mass, after SCI.

Influence of motor complete spinal cord injury on visceral and subcutaneous adipose tissue measured by multi-axial magnetic resonance imaging.

OBJECTIVE: Abdominal obesity conveys substantial health risks, in association with high levels of visceral adipose tissue (VAT), subcutaneous adipose tissue (SAT) and an increased proportion of VAT to SAT. The purposes were to determine the influence of spinal cord injury (SCI) on the associations between single axial cross-sectional area (CSA) slices and the average CSA or volumes of VAT and SAT across multi-axial slices of magnetic resonance imaging (MRI); and the relationships relative to the whole body composition and anthropometrics. METHODS: Thirteen healthy male participants with traumatic motor complete SCI underwent fast spin-echo MRI to measure VAT and SAT across multi-axial slices, followed by dual-energy X-ray absorptiometry to measure whole body fat-free mass (FFM) and fat mass (FM). Waist circumference (WC) was also measured in the seated position. RESULTS: The trunk CSAs of VAT and SAT were 99 +/- 51 and 164 +/- 69 cm2, respectively, and the ratio of VAT to SAT was 0.68 +/- 0.33. The CSAs of VAT and SAT at a single slice strongly predicted the average CSA and modestly predicted the volumes across multi-axial slices. VAT and SAT represented 5.7 +/- 1.8% and 9.7 +/- 3.2% of the total body FM, respectively. Percent body FFM was negatively related to VAT and SAT volumes, but not to a single axial CSA. CONCLUSION: A single slice CSA can modestly predict the volume of multi-axial slices in individuals with SCI, yet it is not related to any of the body composition variables. Increased percent FFM is associated with a reduction in VAT and SAT volumes measured across multi-axial slices. The ratio of VAT to SAT is greater than 0.4, suggesting that individuals with SCI are at high risk of developing metabolic sequelae.