The Effect of Water Immersion during Exercise on Cerebral Blood Flow

Introduction: Regular exercise induces recurrent increases in cerebrovascular perfusion. In peripheral arteries, such episodic increases in perfusion are responsible for improvement in arterial function and health. We examined the hypothesis that exercise during immersion augments cerebral blood flow velocity compared with intensity-matched land-based exercise. Methods: Fifteen normotensive participants were recruited (26 ± 4 yr, 24.3 ± 1.9 kg·m−2). We continuously assessed mean arterial blood pressure, HR, stroke volume, oxygen consumption, and blood flow velocities through the middle and posterior cerebral arteries before, during, and after 20-min bouts of water- and land-based stepping exercise of matched intensity. The order in which the exercise conditions were performed was randomized between subjects. Water-based exercise was performed in 30°C water to the level of the right atrium. Results: The water- and land-based exercise bouts were closely matched for oxygen consumption (13.3 mL·kg−1·min−1 (95% confidence interval (CI), 12.2–14.6) vs 13.5 mL·kg−1·min−1 (95% CI, 12.1–14.8), P = 0.89) and HR (95 bpm (95% CI, 90–101) vs 96 bpm (95% CI, 91–102), P = 0.65). Compared with land-based exercise, water-based exercise induced an increase in middle cerebral artery blood flow velocity (74 cm·s−1 (95% CI, 66–81) vs 67 cm·s−1 (95% CI, 60–74) P < 0.001), posterior cerebral artery blood flow velocity (47 cm·s−1 (95% CI, 40–53) vs 43 cm·s−1 (95% CI, 37–49), P < 0.001), mean arterial blood pressure (106 mm Hg (95% CI, 100–111) vs 101 mm Hg (95% CI, 95–106), P < 0.001), and partial pressure of expired CO2 (P ≤ 0.001). Conclusions: Our findings suggest that water-based exercise augments cerebral blood flow, relative to land-based exercise of similar intensity, in healthy humans

Asthma and COPD in cystic fibrosis intron-8 5T carriers. A population-based study

BACKGROUND: Carriers of cystic fibrosis intron-8 5T alleles with high exon-9 skipping could have increased annual lung function decline and increased risk for asthma or chronic obstructive pulmonary disease (COPD). METHODS: We genotyped 9131 individuals from the adult Danish population for cystic fibrosis 5T, 7T, 9T, and F508del alleles, and examined associations between 11 different genotype combinations, and annual FEV(1 )decline and risk of asthma or COPD. RESULTS: 5T heterozygotes vs. 7T homozygous controls had no increase in annual FEV(1 )decline, self-reported asthma, spirometry-defined COPD, or incidence of hospitalization from asthma or COPD. In 5T/7T heterozygotes vs. 7T homozygous controls we had 90% power to detect an increase in FEV(1 )decline of 8 ml, an odds ratio for self-reported asthma and spirometry-defined COPD of 1.9 and 1.7, and a hazard ratio for asthma and COPD hospitalization of 1.8 and 1.6, respectively. Both 5T homozygotes identified in the study showed evidence of asthma, while none of four 5T/F508del compound heterozygotes had severe pulmonary disease. 7T/9T individuals had annual decline in FEV(1 )of 19 ml compared with 21 ml in 7T homozygous controls (t-test:P = 0.03). 6.7% of 7T homozygotes without an F508del allele in the cystic fibrosis transmembrane conductance regulator gene reported asthma vs. 11% of 7T/9T individuals with an F508del allele (χ(2):P = 0.01) and 40% of 7T homozygotes with an F508del allele (P = 0.04). 7T homozygotes with vs. without an F508del allele also had higher incidence of asthma hospitalization (log-rank:P = 0.003); unadjusted and adjusted equivalent hazard ratios for asthma hospitalization were 11 (95%CI:1.5–78) and 6.3 (0.84–47) in 7T homozygotes with vs. without an F508del allele. CONCLUSION: Polythymidine 5T heterozygosity is not associated with pulmonary dysfunction or disease in the adult Caucasian population. Furthermore, our results support that F508del heterozygosity is associated with increased asthma risk independently of the 5T allele

Guidelines for the management of pregnancy in women with cystic fibrosis

Women with cystic fibrosis (CF) now regularly survive into their reproductive years in good health and wish to have a baby. Many pregnancies have been reported in the literature and it is clear that whilst the outcome for the baby is generally good and some mothers do very well, others find either their CF complicates the pregnancy or is adversely affected by the pregnancy. For some, pregnancy may only become possible after transplantation. Optimal treatment of all aspects of CF needs to be maintained from the preconceptual period until after the baby is born. Clinicians must be prepared to modify their treatment to accommodate the changing physiology during pregnancy and to be aware of changing prescribing before conception, during pregnancy, after birth and during breast feeding. This supplement offers consensus guidelines based on review of the literature and experience of paediatricians, adult and transplant physicians, and nurses, physiotherapists, dietitians, pharmacists and psychologists experienced in CF and anaesthetist and obstetricians with experience of CF pregnancy. It is hoped they will provide practical guidelines helpful to the multidisciplinary CF teams caring for pregnant women with CF

Cardiorespiratory and metabolic responses to treadmill versus water immersion to the neck exercise in elite distance runners

The purpose of this study was to compare the following: a) the cardiorespiratory responses, in elite endurance runners familiar with water immersion to the neck non—weight bearing ( WI) running, at ventilatory threshold (Tvent) and at maximal effort (ie. VO2m) for treadmill and WI running performance to exhaustion and b) the cardiorespiratory and metabolic responses to prolonged performance (42 mm.) at exercise intensities reflecting the treadmill and WI Tvent. Thirteen endurance trained runners familiar with water running completed comparable treadmill and WI VO2max tests. Oxygen consumption (V02), ventilation (ye), heart-rate (HR), respiratory exchange ratio (RER), ratings of perceived exertion ( RPE) and stride frequency (SF) were measured at Tvent and VO2max. Blood lactate [BLa] samples were obtained 30 seconds and 5 minutes post—test. Correlated t—tests revealed significantly (p<O.05) higher VO2max (59.7 vs 54.6 mlkgmin), HRmax (190 vs 175 bpm), RERmax (1.20 vs 1.10), V02 at Tvent (46.3 vs 42.8 mlkgmin1),HR at Tvent (165 vs 152 bpm) for the treadmill vs WI, respectively. Similar values were recorded for Vemax (109.0 vs 105.8 lmin), Ve at Tvent (66.4 vs 65.7 lmin), RER at Tvent (0.99 vs 0.89) and post—test [BLaJ at 30 sec (10.4 vs 9.8 mmoll) and 5 mm post—test (9.7 vs 9.2 mmoll1)for the two conditions. Wilcoxons matched pairs signed—ranks test revealed no differences in RPE at Tvent and VO2max level for the two conditions. Significantly higher SF values over time were recorded (88 vs 54 stridesmin, averaged over time) on the treadmill. The lower WI VO2max with similar peak [ BLa) and lower SF suggests that the active musculature and muscle recruitment patterns differ in WI running due to the high viscocity friction of water, and the non—weight bearing nature of WI running. During steady state exercise at treadmill and WI Tvent no differences in Ve response to exercise were noted in the treadmill and WI conditions. [BLa] response exhibited a decreasing trend over time in the WI condition both during the treadmill and WI Tvent intensity tests. Similar HR values were exhibited for exercise at WI Tvent in both conditions, confirming that the lower HR exhibited at Tvent from the WI VO2max test was related to the lower V02 at WI Tvent and not the WI condition. Significantly lower HR values were exhibited for exercise at treadmill Tvent in the WI versus the treadmill condition suggesting that HR is lower only at workloads corresponding to and above 84.8 % of WI VO2max. Results suggest that exercise in the water immersion to the neck condition affects ( reduces) HR and [BLa) response over time, with the intensity of exercise being a factor. The WI condition, however does not affect Ve and RPE responses.Education, Faculty ofCurriculum and Pedagogy (EDCP), Department ofGraduat

Osteoporosis in cystic fibrosis : pathogenesis and clinical features

Objectives: Advances in the treatment of cystic fibrosis (CF) have lead to increased longevity and with it increased risk for a new set of complications including increased risk for osteoporosis. The purpose of the study was to elucidate the prevalence of low bone mineral density (BMD) in an adult CF population with heterogeneous severity of pulmonary disease and to ascertain clinical and laboratory correlates of low BMD. Methodology: The study design was a cross sectional investigation of BMD at one adult CF clinic. We measured spinal (Ll-4) and femoral BMD by dual energy x-ray absorptiometry (DEXA) in 68 (24 female) CF adults aged 18-55 years. The BMD standard scores for spine and femoral neck were averaged and the composite score used for analyses. Differences in disease severity, exercise capacity and physical activity level, dietary intake, body composition and body mass index, bone turnover, pubertal status, glucocorticoid use, vertebral and non-vertebral fracture rate, and back pain were investigated for associations with changes in BMD. Results: Out of our sample of 68 patients tested, we identified 58 patients with low BMD with 9 patients classified as osteoporotic. Low BMD was associated with declining pulmonary function and increasing age. Late diagnosis of CF was associated with low BMD in adulthood. Multiple regression analysis identified exercise capacity and body mass index as the most significant variables predicting changes in BMD. Current dietary intake was not predictive of present BMD, however inadequate intakes of calcium and vitamin D were documented. Body composition was moderately associated with BMD. Onset of puberty was delayed in those who showed decreased BMD in adulthood. Kyphosis and back pain were not predictive of low spinal BMD. Conclusions: Low BMD is common in adult CF patients. Increased severity of pulmonary disease, poor exercise tolerance and inadequate weight gain contribute to BMD deficits in adulthood. Delayed diagnosis of CF also contributes to low BMD in adulthood. Several other clinical and nutritional factors contribute to BMD deficits.Medicine, Faculty ofMedicine, Department ofExperimental Medicine, Division ofGraduat