C-reactive protein, metabolic syndrome, and insulin resistance in individuals with spinal cord injury.

BACKGROUND/OBJECTIVE: High-sensitivity C-reactive protein (hsCRP) has been shown to be indicative of elevated risk of cardiovascular disease (CVD). We examined this blood marker in persons with spinal cord injury (SCI) in order to determine its potential for predicting elevated cardiac risk. METHODS: In a cross-sectional analysis, we examined the relationship between hsCRP and insulin resistance and metabolic syndrome among 93 individuals with SCI (50.2 +/- 13 years). Fasting lipids, insulin, glucose, plasma hsCRP, and anthropometric data were gathered from each subject. Comparisons were made with population reference values. RESULTS: Metabolic syndrome and insulin resistance were present in nearly one quarter of the SCI population (22.6%). Subjects with fasting insulin resistance had significantly higher mean hsCRP (4.29 +/- 3.25 mg/L) than those who were not insulin resistant (2.24 +/- 2.02) (P < 0.05). Moreover, hsCRP was significantly elevated in individuals who presented with high cardiovascular risk including severe dyslipidemia (> or = 4 abnormal lipid values) and Framingham Risk scores < or = 6 (P < 0.05 for both values). In addition, the homeostasis model assessment of insulin resistance was mildly correlated with hsCRP (r = 0.33). CONCLUSIONS: In individuals with SCI who are insulin resistant and/or display components of the metabolic syndrome, hsCRP is elevated suggesting a clinically important association with cardiovascular risk in this population.

Heart rate as a predictor of energy expenditure in people with spinal cord injury.

This study evaluated the accuracy of heart rate calibrated from a maximum exercise test for predicting energy expenditure during five activities of daily living (ADL) in participants with spinal cord injury (SCI). Thirteen individuals with SCI underwent maximum exercise testing, followed by portable heart rate and metabolic testing during five ADL. A regression equation was developed from heart rate and oxygen uptake responses during the maximum exercise test for each subject. Based on this individualized equation, heart rate measured during the ADL was used to estimate energy expenditure for each participant. Predicted energy expenditure from heart rate was compared with that measured by indirect calorimetry with the use of oxygen uptake. Heart rate derived from the individualized regression equations explained 55% of the variance in measured energy expenditure, compared with only 8.3% from heart rate alone. However, calibrated heart rate consistently overestimated the actual kilocalories used; on average, the estimated energy expenditure was roughly 25% higher than that measured by oxygen uptake. Heart rate can be used as a gross estimate of energy expenditure during higher-intensity ADL in people with SCI when individual calibration of heart rate from maximum exercise testing is used.