Objectives This study aimed to evaluate the relationship between lung function and body composition in cystic fibrosis (CF) and examine the presence of normal weight obesity (NWO), a high body fat percentage with a normal body mass index (BMI), in this population. Research Methods & Procedures In a pilot, cross-sectional study, 32 subjects with CF and a reference group of 20 adults without CF underwent body composition analysis with air displacement plethysmography. NWO was defined as a BMI <25 kg/m2 and body fat >30% (women) or >23% (men). Lung function in subjects with CF was determined by the percentage of predicted forced expiratory volume in 1 second (FEV1% predicted). Results Despite lower BMI and fat-free mass index (P<0.01), fat mass index and percent body fat did not differ between CF subjects and the reference group. Among CF subjects, FEV1% predicted was positively associated with fat-free mass index (β=6.31 ± 2.93, P=0.04) and inversely associated with fat mass index (β= −6.44 ± 2.93, P=0.04), after adjusting for age, gender and BMI. Ten CF subjects (31%) had NWO, which corresponded with lower fat-free mass index and FEV1% predicted compared to overweight subjects (P=0.006 and 0.004, respectively). Conclusions Excess adiposity, particularly in the form of NWO, was inversely associated with lung function in CF. Larger prospective studies should confirm these findings and determine the long-term metabolic and clinical consequences of excess adiposity in CF. As the lifespan of individuals with CF increases, nutrition screening protocols, which primarily rely on BMI, may require re-assessment.

Chronic kidney disease (CKD) patients have exercise intolerance associated with increased cardiovascular mortality. Previous studies demonstrate that blood pressure (BP) and sympathetic nerve responses to handgrip exercise are exaggerated in CKD. These patients also have decreased nitric oxide (NO) bioavailability and endothelial dysfunction, which could potentially lead to an impaired ability to vasodilate during exercise. We hypothesized that CKD patients have exaggerated BP responses during maximal whole body exercise and that endothelial dysfunction correlates with greater exercise pressor responses in these patients. Brachial artery flow-mediated dilation (FMD) was assessed before maximal treadmill exercise in 56 participants: 38 CKD (56.7 ± 1.2 yr old, 38 men) and 21 controls (52.8 ± 1.8 yr old, 20 men). During maximal treadmill exercise, the slope-of-rise in systolic BP (+10.32 vs. +7.75 mmHg/stage, < 0.001), mean arterial pressure (+3.50 vs. +2.63 mmHg/stage, = 0.004), and heart rate (+11.87 vs. +10.69 beats·min·stage, = 0.031) was significantly greater in CKD compared with controls. Baseline FMD was significantly lower in CKD (2.76 ± 0.42% vs. 5.84 ± 0.97%, = 0.008). Lower FMD values were significantly associated with a higher slope-of-rise in systolic BP (+11.05 vs. 8.71 mmHg/stage, = 0.003) during exercise in CKD, as well as poorer exercise capacity measured as peak oxygen uptake (V̇o; 19.47 ± 1.47 vs. 24.57 ± 1.51 ml·min·kg, < 0.001). These findings demonstrate that low FMD in CKD correlates with augmented BP responses during exercise and lower V̇o, suggesting that endothelial dysfunction may contribute to exaggerated exercise pressor responses and poor exercise capacity in CKD patients.

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