Biomedical subjects

Ifigenia Giannopoulou

Publications and source records attributed to Ifigenia Giannopoulou.

7 recordsLinked to original sources

PubMed2006

Effects of exercise-induced arterial hypoxaemia and work rate on diaphragmatic fatigue in highly trained endurance athletes.

Diaphragmatic fatigue occurs in highly trained athletes during exhaustive exercise. Since approximately half of them also exhibit exercise-induced arterial hypoxaemia (EIAH) during high-intensity exercise, the present study sought to test the hypothesis that arterial hypoxaemia contributes to exercise-induced diaphragmatic fatigue in this population. Ten cyclists ( : 70.0 +/- 1.6 ml kg(-1) min(-1); mean +/-s.e.m.) completed, in a balanced ordering sequence, one normoxic (end-exercise arterial O(2) saturation (S(a,O(2))): 92 +/- 1%) and one hyperoxic (F(I,O(2)): 0.5% O(2); S(a,O(2)) : 97 +/- 1%) 5 min exercise test at intensities equal to 80 +/- 3 and 90 +/- 3% of maximal work rate (WR(max)), respectively, producing the same tidal volume (V(T)) and breathing frequency (f) throughout exercise. Cervical magnetic stimulation was used to determine reduction in twitch transdiaphragmatic pressure (P(di,tw)) during recovery. Hyperoxic exercise at 90% WR(max) induced significantly (P= 0.022) greater post-exercise reduction in P(di,tw) (15 +/- 2%) than did normoxic exercise at 80% WR(max) (9 +/- 2%), despite the similar mean ventilation (123 +/- 8 and 119 +/- 8 l min(-1), respectively), breathing pattern (V(T): 2.53 +/- 0.05 and 2.61 +/- 0.05 l, f: 49 +/- 2 and 46 +/- 2 breaths min(-1), respectively), mean changes in P(di) during exercise (37.1 +/- 2.4 and 38.2 +/- 2.8 cmH(2)O, respectively) and end-exercise arterial lactate (12.1 +/- 1.4 and 10.8 +/- 1.1 mmol l(-1), respectively). The difference found in diaphragmatic fatigue between the hyperoxic (at higher leg work rate) and the normoxic (at lower leg work rate) tests suggests that neither EIAH nor lactic acidosis per se are likely predominant causative factors in diaphragmatic fatigue in this population, at least at the level of S(a,O(2)) tested. Rather, this result leads us to hypothesize that blood flow competition with the legs is an important contributor to diaphragmatic fatigue in heavy exercise, assuming that higher leg work required greater leg blood flow.

Adult↗

PubMed2006

Cardiac autonomic control in individuals with Down syndrome.

Our goal in this study was to compare cardiac autonomic control at rest between 50 individuals with Down syndrome and 24 control participants without disabilities. Resting autonomic function was assessed using analysis of heart rate variability. Participants with Down syndrome had reduced total heart rate variability, which indicates possible autonomic dysfunction in this population. Their VO2 peak and BMI were not significantly correlated with resting cardiac autonomic control. This may suggest that fitness level and obesity differentially affect cardiac autonomic control in persons with Down syndrome compared to their healthy, nondisabled peers.

Adult↗

PubMed2005

Impaired vagal modulation of heart rate in individuals with Down syndrome.

The attenuated heart rate (HR) and blood pressure (BP) response to exercise in individuals with Down syndrome (DS) has been attributed to autonomic dysfunction, which has been associated with obesity. Our purpose was to determine the role of autonomic control of HR to the attenuated chronotropic response observed in individuals with DS. We evaluated spectral analysis of HR variability (HRV) in 13 individuals with (BMI 32+/-5 kg/m(2), P<0.05) and 14 without DS (BMI 26+/-3 kg/m(2)) by means of 2 min isometric handgrip at 30% of maximal force followed by recovery. Noninvasive measures of HR (ECG) and systolic BP (SBP) (Portapres) were recorded continuously. The increases in HR and SBP, and decrease in high frequency (HF) component were significantly greater in controls than in individuals with DS (P<0.05) during handgrip. The increase in LF/HF ratio was not significantly affected by handgrip and was comparable in both groups. During recovery, the decreases in HR, SBP, and LF/HF ratio, and the increase in HF were significantly greater in controls than in individuals with DS (P<0.05). Controlling for BMI did not alter these results. The attenuated HR and SBP response to the handgrip test in individuals with DS is explained by blunted vagal modulation. Our study suggests that autonomic dysfunction in individuals with DS might be independent of obesity.

Adolescent↗

PubMed2005

Blunted heart rate response to upright tilt in people with Down syndrome.

OBJECTIVES: To determine whether heart rate and blood pressure responses to upright tilt would be lower in subjects with Down syndrome (DS) than in control subjects with no disabilities. DESIGN: Comparative study. SETTING: University research laboratory. PARTICIPANTS: Nineteen people with DS (mean age, 25.1+/-7.3 y) and 17 control subjects without disabilities (mean age, 28.4+/-5.6 y). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Heart rate and blood pressure recordings were obtained at rest and during a 2-minute period of passive head up tilt to 80 degrees . RESULTS: Heart rate and blood pressure increased significantly during the first 30 seconds of upright tilt in both groups ( P <.05) and then stabilized for the remainder of the test. The initial heart rate response to head up tilt (first 30s) was significantly higher in controls compared with subjects with DS ( P <.05), whereas the blood pressure response did not differ between groups ( P >.05). Controlling for heart rate reserve showed a blunted heart rate response through the tilt period in subjects with DS. CONCLUSIONS: These data show a blunted heart rate response to upright tilt in people with DS, despite similar changes in blood pressure, consistent with reduced sympathoexcitation and possibly altered baroreceptor function in these people with DS.

Adolescent↗

PubMed2005

Effects of diet and/or exercise on the adipocytokine and inflammatory cytokine levels of postmenopausal women with type 2 diabetes.

This study examined the independent and combined effects of diet and exercise on adipocytokine and inflammatory cytokines in postmenopausal women with type 2 diabetes. Using a randomized, controlled design, 33 women (age, 50-70 years) were assigned to diet alone (D), exercise alone (EX), or diet + exercise (D + E) for 14 weeks. Before and after the interventions, blood samples for adipocytokines and inflammatory markers were drawn, a meal test was performed, and abdominal fat distribution was measured by magnetic resonance imaging (MRI). Body weight decreased approximately 4.5 +/- 0.6 kg ( P < .05) after the D and D + E interventions, whereas only small changes in body weight were found with the exercise-alone intervention. Plasma C-reactive protein levels were decreased by approximately 15% with all 3 interventions, whereas leptin levels were reduced with the D and D + E intervention (D: pre = 48.7 +/- 6.0, post = 38.9 +/- 5.0 ng/mL; D + E: pre = 38.5 +/- 6.0, post = 22.9 +/- 5.0 ng/mL; P < .05) with no differences between groups. There was a trend for leptin levels to decrease in the EX group ( P = .06). Plasma resistin levels were not altered by the 3 interventions from pre- to posttreatment (D: pre = 6.9 +/- 0.6, post = 6.2 +/- 0.4 ng/mL; D + E: pre = 5.6 +/- 0.6, post = 5.7 +/- 0.4 ng/mL; E: pre = 6.2 +/- 0.6, post = 5.9 +/- 0.6 ng/mL, P > .05), and no differences in adiponectin and tumor necrosis factor alpha (TNF- alpha ) levels were found. Visceral adipose tissue and tumor necrosis factor alpha were the only predictors of calculated insulin resistance ( P < .05), explaining 43% of the variability. A typically prescribed weight loss program with lifestyle changes resulted in few changes in adipocytokines and inflammatory cytokines in older women with type 2 diabetes, suggesting that dramatic weight loss or clinical interventions are needed.

Aged↗

PubMed2005

Baroreflex sensitivity during static exercise in individuals with Down Syndrome.

INTRODUCTION: Individuals with Down syndrome (DS) have altered heart rate (HR) and blood pressure (BP) responses to orthostatic challenges and isometric handgrip (IHG) exercise, suggesting possible alteration in baroreflex sensitivity. PURPOSE: This study investigated baroreflex sensitivity (BRS) as a potential mechanism contributing to chronotropic incompetence during IHG in persons with DS. METHODS: Heart rate and BP were continually recorded in 12 individuals with DS and 10 controls, at rest and during 2 min of IHG, at 30% of maximal voluntary contraction (MVC). Spontaneous BRS was derived via the sequence method. RESULTS: No differences were seen in HR at rest between groups. Systolic BP (SBP) was significantly lower in the DS group at rest (106.1+/- 2.9 vs 116.5+/- 3.9 mm Hg, P < 0.05) and during IHG (123.9+/- 4.6 vs 150.1+/- 5.3 mm Hg, P<0.001). A significant group-by-task interaction was found for both change in HR and change in SBP with IHG, because of an attenuated HR and SBP response to IHG in participants with DS (P<0.05). When controlling for resting SBP, the DS group had a lower BRS at rest (16.0+/-1.7 vs 21.2+/-4.2 ms.mm Hg, P< 0.05) and during IHG (7.8 +/-1.0 vs 12.1+/- 2.6 ms.mm Hg, P< 0.05). CONCLUSIONS: Individuals with DS have lower BRS at rest and during IHG than controls and this may be related to their attenuated HR response during perturbation.

Adult↗

PubMed2005

Resting metabolic rate is not reduced in obese adults with Down syndrome.

Resting metabolic rate (RMR) of 22 individuals with Down syndrome was compared to that of 20 nondisabled control individuals of similar age (25.7 and 27.4 years, respectively). Using a ventilated hood system, we measured RMR in the early morning after an overnight fast. Peak aerobic capacity (VO2peak) and body composition were also determined. Resting metabolic rate was not different between groups. Adjusting RMR for body weight or body surface area did not change these findings. Using stepwise regression for the total population and each subgroup, we found that only body surface area was a significant predictor of RMR. These data show that individuals with Down syndrome do not have lower RMR than their nondisabled peers, suggesting that reduced RMR does not explain the high incidence of obesity in this population.

Adolescent↗