Arturo Figueroa - Academia.edu (original) (raw)

Papers by Arturo Figueroa

Metabolism-clinical and Experimental, 2005

This study examined the independent and combined effects of diet and exercise on adipocytokine an... more 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~4.5 F 0.6 kg ( P b .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~15% with all 3 interventions, whereas leptin levels were reduced with the D and D + E intervention (D: pre = 48.7 F 6.0, post = 38.9 F 5.0 ng/mL; D + E: pre = 38.5 F 6.0, post = 22.9 F 5.0 ng/mL; P b .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 F 0.6, post = 6.2 F 0.4 ng/mL; D + E: pre = 5.6 F 0.6, post = 5.7 F 0.4 ng/mL; E: pre = 6.2 F 0.6, post = 5.9 F 0.6 ng/mL, P N .05), and no differences in adiponectin and tumor necrosis factor a (TNF-a) levels were found. Visceral adipose tissue and tumor necrosis factor a were the only predictors of calculated insulin resistance ( P b .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. D

American Journal of Cardiology, 2009

Individuals with Down syndrome (DS) exhibit low peak aerobic capacities and heart rates. Although... more Individuals with Down syndrome (DS) exhibit low peak aerobic capacities and heart rates. Although autonomic modulation is attenuated in individuals with DS at rest, the exercise response appears normal. This suggests that mechanisms other than autonomic control influence the low aerobic capacity, such as catecholamine responsiveness to exercise. The purpose of this study was to determine catecholamine responses to a peak treadmill test in a group of subjects with DS compared with a nondisabled group. Epinephrine and norepinephrine concentrations were measured at rest and immediately after graded exercise tests on a treadmill in 20 subjects with DS (mean age, 24 +/- 7 years) and 21 nondisabled subjects (mean age, 26 +/- 6 years). Catecholamines increased significantly with peak exercise in the control group (p <0.05), with little to no change in subjects with DS. In conclusion, the different catecholamine responses to peak exercise, in particular the lack of a response in individuals with the DS, may be a primary mechanism to explain the reduced peak heart rates and low work capacities observed in this population.

Journal of Applied Physiology, 2009

Force variability is greater in individuals with Down syndrome (DS) compared with persons without... more Force variability is greater in individuals with Down syndrome (DS) compared with persons without DS and is similar to that seen with normal aging. The purpose of this study was to examine the structure (in both time and frequency domains) of force output variability in persons with DS to determine whether deficits in force control are similar between individuals with DS and older adults. An isometric handgrip task at a constant force (30% of maximal voluntary contraction) was completed by individuals with DS (n = 29, age 26 yr), and healthy young (n = 26, age 27 yr) and older (n = 33, age 70 yr) individuals. Mean, standard deviation (SD), and coefficient of variation (CV) were used to analyze the magnitude of force output variability. Spectral analysis and approximate entropy (ApEn) were used to analyze the structure of force output variability. Mean force output for DS was lower than in young controls (P < 0.05) but no different from old controls. Individuals with DS had greater SD and CV than young and old controls (P < 0.05). The DS group had a significantly greater proportion of spectral power within the 0-to 4-Hz bandwidth than the young and older controls (P < 0.05). The DS group had significantly lower ApEn values than the young controls (P < 0.05), but there were no differences in ApEn between the DS group and the old controls (P > 0.05). In conclusion, young persons with DS demonstrate enhanced temporal structure and greater amplitude of low-frequency oscillations in the force output signal than age-matched non-DS peers. Interestingly, young persons with DS and older persons without DS have similar time-dependent structure of force output variability. This would suggest a possible link between premature aging and less complex force output in persons with DS.

Clinical Autonomic Research, 2008

Objective To compare autonomic function, measured during handgrip (HG) and cold pressor (CP), bet... more Objective To compare autonomic function, measured during handgrip (HG) and cold pressor (CP), between obese with and without type 2 diabetes and non-obese women in fasting and post-glucose load states. Methods Twelve obese women with type 2 diabetes (50 ± 1 years), 15 obese women without type 2 diabetes (48 ± 2 years), and 12 non-obese women (49 ± 2 years) participated in this study. Heart rate variability (HRV) was determined during autonomic function tests, conducted in both the fasting state and after a glucose challenge (oral glucose tolerance test-OGTT). Results Obese women with and without diabetes and non-obese women responded similarly fasted and post-glucose challenge, such that in the fasted state low frequency power normalized (LF(nu)) to total power (TP), log transformed (Ln) low frequency to high frequency ratio (LnLF/HF) and heart rate (HR) significantly increased with the autonomic functional tasks (P < 0.05), whereas HF(nu) significantly decreased with the tasks (P < 0.05). Handgrip elicited a lower LnTP and a higher HR (P < 0.05) when compared to CP in the fasted state. In the glucose challenged state LF(nu), LnLF/HF and HR increased (P < 0.05) and HF(nu) significantly decreased (P < 0.05). Interpretation Results of autonomic testing did not differ between obese women, with and without diabetes, and non-obese women. The HG test elicited a greater reduction in HRV total power compared to the CP. This suggests that HG may be more useful when examining autonomic function in women with complicated diabetes.

Mental Retardation, 2005

Resting metabolic rate (RMR) of 22 individuals with Down syndrome was compared to that of 20 nond... more 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.

Archives of Physical Medicine and Rehabilitation, 2005

Fernhall B, Figueroa A, Collier S, Baynard T, Giannopoulou I, Goulopoulou S. Blunted heart rate r... more Fernhall B, Figueroa A, Collier S, Baynard T, Giannopoulou I, Goulopoulou S. Blunted heart rate response to upright tilt in people with Down syndrome. Arch Phys Med Rehabil 2005;86:813-8.

Research in Developmental Disabilities, 2010

European Journal of Cardiovascular Prevention & Rehabilitation, 2007

Background Type 2 diabetes is associated with cardiovascular autonomic dysfunction. Postexercise ... more Background Type 2 diabetes is associated with cardiovascular autonomic dysfunction. Postexercise autonomic modulation may be different in obese individuals with and without type 2 diabetes. We examined postexercise responses in nondiabetic and diabetic women aged 40-60 years. Methods Hemodynamics, high-frequency and low-frequency of RR interval, low-frequency of systolic blood pressure variability and baroreflex sensitivity were evaluated before and after a 20 min walk at B65% of VO 2 peak in eight lean, 12 obese without type 2 diabetes and eight women with type 2 diabetes. Postexercise measurements were obtained at 10-15, 20-25 and 30-35 min.

Clinical Autonomic Research, 2005

The attenuated heart rate (HR) and blood pressure (BP) response to exercise in individuals with D... more 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/m2, P<0.05) and 14 without DS (BMI 26±3 kg/m2) 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.

Medicine and Science in Sports and Exercise, 2003

Metabolism-clinical and Experimental, 2007

This study examined the effect of glucose ingestion on cardiac autonomic function in non-obese wo... more This study examined the effect of glucose ingestion on cardiac autonomic function in non-obese women and obese women with and without type 2 diabetes. Heart rate variability (HRV) was measured via continuous ECG and beat-by-beat blood pressure was recorded with finger photoplethysmography (Portapress) in a fasted state and in response to a 75 g glucose load in 42 middle-aged women (40-60 yr). Upright tilt was also utilized as an orthostatic stress to provide a clinically relevant challenge to the cardiovascular system. Significant main effects for log transformed (Ln) total power (TP, msec 2 ) were observed with upright tilt (P<0.01) and glucose challenge (P<0.05). LnTP decreased in all groups in both the fasted and fed state with upright tilt (P<0.01), but glucose ingestion resulted in higher LnTP in the supine position only (P=0.008). Tilt resulted in a significant main effect for low frequency (LFnu, normalized units) and high frequency (Hfnu) power (P<0.000), while the glucose challenge had no effect on LFnu or HFnu power. LFnu approached significance for group differences (P=0.07), such that the non-obese had lower LF power than either of the obese groups. Sympathovagal balance (LnLF/HF ratio) was affected by position (P<0.000) and group (P<0.05), with a lower LnLF/HF in the non-obese than in the obese women. Baroreceptor sensitivity decreased (P<0.01) during upright tilt but was not changed by the glucose challenge. In conclusion, basal sympathovagal balance is higher in obese individuals with and without type 2 diabetes. Women with type 2 diabetes showed no differences in autonomic function with an orthostatic challenge or glucose load than non-diabetic, obese women. The glucose load did alter total spectral power in all of these middle-aged women, but had no impact on baroreceptor sensitivity.

Medicine and Science in Sports and Exercise, 2005

Introduction: Individuals with Down syndrome (DS) have altered heart rate (HR) and blood pressure... more 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 Ϯ 2.9 vs 116.5 Ϯ 3.9 mm Hg, P Ͻ 0.05) and during IHG (123.9 Ϯ 4.6 vs 150.1 Ϯ 5.3 mm Hg, P Ͻ 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 Ͻ 0.05). When controlling for resting SBP, the DS group had a lower BRS at rest (16.0 Ϯ 1.7 vs 21.2 Ϯ 4.2 ms⅐mm Hg Ϫ1 , P Ͻ 0.05) and during IHG (7.8 Ϯ 1.0 vs 12.1 Ϯ 2.6 ms⅐mm Hg, Ϫ1 P Ͻ 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.

European Journal of Applied Physiology, 2007

Obesity and type 2 diabetes (T2D) are associated with abnormal cardiovascular autonomic function ... more Obesity and type 2 diabetes (T2D) are associated with abnormal cardiovascular autonomic function and increased risk for cardiac complications, especially after exercise. Since improvements at rest are not always observed after training, we investigated changes in resting and post-exercise autonomic function in obese women with and without T2D after16-week of walking training. Heart rate (HR) variability (HRV) and baroreflex sensitivity (BRS) were measured at rest and 20 min after a 20 min bout of treadmill exercise at 65% VO2 peak in obese women with (n = 8) and without T2D (n = 12) before and after training. HRV was analyzed by frequency-domain [high- (HF) power and low-frequency (LF)] and BRS by the sequence method. Exercise training induced similar significant changes in VO2 peak, resting systolic blood pressure (SBP) and post-exercise autonomic function in both groups. Training increased VO2 peak (6%; P < 0.01) and decreased resting SBP (8%; P < 0.001). Increased post-exercise HR recovery (5%; P < 0.001), HF power (14%; P < 0.05), LF power (14%; P < 0.05) and BRS (86%; P < 0.001) were also observed. Resting autonomic function and post-exercise SBP were not altered after training. In conclusion, endurance training reduced blood pressure without changes in HRV and BRS at rest, but training increased HRV and BRS during the recovery of acute endurance exercise indicating an improved post-exercise autonomic modulation of HR, which was similar in obese women with and without T2D.

Medicine and Science in Sports and Exercise, 2004

Purpose: This study established the published prediction equations for the energy expenditure of ... more Purpose: This study established the published prediction equations for the energy expenditure of walking and running compared with the measured values. To make this comparison we first determined whether differences exist in energy expenditure for 1600 m of walking versus running, and whether energy expenditure differences occur due to being on the track or treadmill. Methods: Energy was measured via indirect calorimetry in 24 subjects while walking (1.41 m·s Ϫ1 ) and running (2.82 m·s Ϫ1 ) 1600 m on the treadmill. A subgroup also performed the 1600-m run/walk on the track. The measured energy expenditures were compared with published prediction equations. Results: Running required more energy (P Ͻ 0.01) for 1600 m than walking (treadmill: running 481 Ϯ 20.0 kJ, walking 340 Ϯ 14 kJ; track: running 480 Ϯ 23 kJ, walking 334 Ϯ 14 kJ) on both the track and treadmill. Predictions using the ACSM or Léger equations for running, and the Pandolf equation for walking, were similar to the actual energy expenditures for running and walking (total error: ACSM: Ϫ20 and 14.4 kJ, respectively; Légers walking: Ϫ10.1 kJ; Pandolf walking: Ϫ10.0 kJ). An overestimation (P Ͻ 0.01) for 1600 m was found with the McArdle's table for walking and running energy expenditure and with van der Walt's prediction for walking energy expenditure, whereas the Epstein equation underestimated running energy expenditure (P Ͻ 0.01). Conclusion: Running has a greater energy cost than walking on both the track and treadmill. For running, the Léger equation and ACSM prediction model appear to be the most suitable for the prediction of running energy expenditure. The ACSM and Pandolf prediction equation also closely predict walking energy expenditure, whereas the McArdle's table or the equations by Epstein and van der Walt were not as strong predictors of energy expenditure.

American Journal on Mental Retardation, 2006

Metabolism-clinical and Experimental, 2005

This study examined the independent and combined effects of diet and exercise on adipocytokine an... more 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~4.5 F 0.6 kg ( P b .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~15% with all 3 interventions, whereas leptin levels were reduced with the D and D + E intervention (D: pre = 48.7 F 6.0, post = 38.9 F 5.0 ng/mL; D + E: pre = 38.5 F 6.0, post = 22.9 F 5.0 ng/mL; P b .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 F 0.6, post = 6.2 F 0.4 ng/mL; D + E: pre = 5.6 F 0.6, post = 5.7 F 0.4 ng/mL; E: pre = 6.2 F 0.6, post = 5.9 F 0.6 ng/mL, P N .05), and no differences in adiponectin and tumor necrosis factor a (TNF-a) levels were found. Visceral adipose tissue and tumor necrosis factor a were the only predictors of calculated insulin resistance ( P b .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. D

American Journal of Cardiology, 2009

Individuals with Down syndrome (DS) exhibit low peak aerobic capacities and heart rates. Although... more Individuals with Down syndrome (DS) exhibit low peak aerobic capacities and heart rates. Although autonomic modulation is attenuated in individuals with DS at rest, the exercise response appears normal. This suggests that mechanisms other than autonomic control influence the low aerobic capacity, such as catecholamine responsiveness to exercise. The purpose of this study was to determine catecholamine responses to a peak treadmill test in a group of subjects with DS compared with a nondisabled group. Epinephrine and norepinephrine concentrations were measured at rest and immediately after graded exercise tests on a treadmill in 20 subjects with DS (mean age, 24 +/- 7 years) and 21 nondisabled subjects (mean age, 26 +/- 6 years). Catecholamines increased significantly with peak exercise in the control group (p &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;0.05), with little to no change in subjects with DS. In conclusion, the different catecholamine responses to peak exercise, in particular the lack of a response in individuals with the DS, may be a primary mechanism to explain the reduced peak heart rates and low work capacities observed in this population.

Journal of Applied Physiology, 2009

Force variability is greater in individuals with Down syndrome (DS) compared with persons without... more Force variability is greater in individuals with Down syndrome (DS) compared with persons without DS and is similar to that seen with normal aging. The purpose of this study was to examine the structure (in both time and frequency domains) of force output variability in persons with DS to determine whether deficits in force control are similar between individuals with DS and older adults. An isometric handgrip task at a constant force (30% of maximal voluntary contraction) was completed by individuals with DS (n = 29, age 26 yr), and healthy young (n = 26, age 27 yr) and older (n = 33, age 70 yr) individuals. Mean, standard deviation (SD), and coefficient of variation (CV) were used to analyze the magnitude of force output variability. Spectral analysis and approximate entropy (ApEn) were used to analyze the structure of force output variability. Mean force output for DS was lower than in young controls (P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.05) but no different from old controls. Individuals with DS had greater SD and CV than young and old controls (P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.05). The DS group had a significantly greater proportion of spectral power within the 0-to 4-Hz bandwidth than the young and older controls (P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.05). The DS group had significantly lower ApEn values than the young controls (P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.05), but there were no differences in ApEn between the DS group and the old controls (P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt; 0.05). In conclusion, young persons with DS demonstrate enhanced temporal structure and greater amplitude of low-frequency oscillations in the force output signal than age-matched non-DS peers. Interestingly, young persons with DS and older persons without DS have similar time-dependent structure of force output variability. This would suggest a possible link between premature aging and less complex force output in persons with DS.

Clinical Autonomic Research, 2008

Objective To compare autonomic function, measured during handgrip (HG) and cold pressor (CP), bet... more Objective To compare autonomic function, measured during handgrip (HG) and cold pressor (CP), between obese with and without type 2 diabetes and non-obese women in fasting and post-glucose load states. Methods Twelve obese women with type 2 diabetes (50 ± 1 years), 15 obese women without type 2 diabetes (48 ± 2 years), and 12 non-obese women (49 ± 2 years) participated in this study. Heart rate variability (HRV) was determined during autonomic function tests, conducted in both the fasting state and after a glucose challenge (oral glucose tolerance test-OGTT). Results Obese women with and without diabetes and non-obese women responded similarly fasted and post-glucose challenge, such that in the fasted state low frequency power normalized (LF(nu)) to total power (TP), log transformed (Ln) low frequency to high frequency ratio (LnLF/HF) and heart rate (HR) significantly increased with the autonomic functional tasks (P < 0.05), whereas HF(nu) significantly decreased with the tasks (P < 0.05). Handgrip elicited a lower LnTP and a higher HR (P < 0.05) when compared to CP in the fasted state. In the glucose challenged state LF(nu), LnLF/HF and HR increased (P < 0.05) and HF(nu) significantly decreased (P < 0.05). Interpretation Results of autonomic testing did not differ between obese women, with and without diabetes, and non-obese women. The HG test elicited a greater reduction in HRV total power compared to the CP. This suggests that HG may be more useful when examining autonomic function in women with complicated diabetes.

Mental Retardation, 2005

Resting metabolic rate (RMR) of 22 individuals with Down syndrome was compared to that of 20 nond... more 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.

Archives of Physical Medicine and Rehabilitation, 2005

Fernhall B, Figueroa A, Collier S, Baynard T, Giannopoulou I, Goulopoulou S. Blunted heart rate r... more Fernhall B, Figueroa A, Collier S, Baynard T, Giannopoulou I, Goulopoulou S. Blunted heart rate response to upright tilt in people with Down syndrome. Arch Phys Med Rehabil 2005;86:813-8.

Research in Developmental Disabilities, 2010

European Journal of Cardiovascular Prevention & Rehabilitation, 2007

Background Type 2 diabetes is associated with cardiovascular autonomic dysfunction. Postexercise ... more Background Type 2 diabetes is associated with cardiovascular autonomic dysfunction. Postexercise autonomic modulation may be different in obese individuals with and without type 2 diabetes. We examined postexercise responses in nondiabetic and diabetic women aged 40-60 years. Methods Hemodynamics, high-frequency and low-frequency of RR interval, low-frequency of systolic blood pressure variability and baroreflex sensitivity were evaluated before and after a 20 min walk at B65% of VO 2 peak in eight lean, 12 obese without type 2 diabetes and eight women with type 2 diabetes. Postexercise measurements were obtained at 10-15, 20-25 and 30-35 min.

Clinical Autonomic Research, 2005

The attenuated heart rate (HR) and blood pressure (BP) response to exercise in individuals with D... more 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/m2, P<0.05) and 14 without DS (BMI 26±3 kg/m2) 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.

Medicine and Science in Sports and Exercise, 2003

Metabolism-clinical and Experimental, 2007

This study examined the effect of glucose ingestion on cardiac autonomic function in non-obese wo... more This study examined the effect of glucose ingestion on cardiac autonomic function in non-obese women and obese women with and without type 2 diabetes. Heart rate variability (HRV) was measured via continuous ECG and beat-by-beat blood pressure was recorded with finger photoplethysmography (Portapress) in a fasted state and in response to a 75 g glucose load in 42 middle-aged women (40-60 yr). Upright tilt was also utilized as an orthostatic stress to provide a clinically relevant challenge to the cardiovascular system. Significant main effects for log transformed (Ln) total power (TP, msec 2 ) were observed with upright tilt (P<0.01) and glucose challenge (P<0.05). LnTP decreased in all groups in both the fasted and fed state with upright tilt (P<0.01), but glucose ingestion resulted in higher LnTP in the supine position only (P=0.008). Tilt resulted in a significant main effect for low frequency (LFnu, normalized units) and high frequency (Hfnu) power (P<0.000), while the glucose challenge had no effect on LFnu or HFnu power. LFnu approached significance for group differences (P=0.07), such that the non-obese had lower LF power than either of the obese groups. Sympathovagal balance (LnLF/HF ratio) was affected by position (P<0.000) and group (P<0.05), with a lower LnLF/HF in the non-obese than in the obese women. Baroreceptor sensitivity decreased (P<0.01) during upright tilt but was not changed by the glucose challenge. In conclusion, basal sympathovagal balance is higher in obese individuals with and without type 2 diabetes. Women with type 2 diabetes showed no differences in autonomic function with an orthostatic challenge or glucose load than non-diabetic, obese women. The glucose load did alter total spectral power in all of these middle-aged women, but had no impact on baroreceptor sensitivity.

Medicine and Science in Sports and Exercise, 2005

Introduction: Individuals with Down syndrome (DS) have altered heart rate (HR) and blood pressure... more 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 Ϯ 2.9 vs 116.5 Ϯ 3.9 mm Hg, P Ͻ 0.05) and during IHG (123.9 Ϯ 4.6 vs 150.1 Ϯ 5.3 mm Hg, P Ͻ 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 Ͻ 0.05). When controlling for resting SBP, the DS group had a lower BRS at rest (16.0 Ϯ 1.7 vs 21.2 Ϯ 4.2 ms⅐mm Hg Ϫ1 , P Ͻ 0.05) and during IHG (7.8 Ϯ 1.0 vs 12.1 Ϯ 2.6 ms⅐mm Hg, Ϫ1 P Ͻ 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.

European Journal of Applied Physiology, 2007

Obesity and type 2 diabetes (T2D) are associated with abnormal cardiovascular autonomic function ... more Obesity and type 2 diabetes (T2D) are associated with abnormal cardiovascular autonomic function and increased risk for cardiac complications, especially after exercise. Since improvements at rest are not always observed after training, we investigated changes in resting and post-exercise autonomic function in obese women with and without T2D after16-week of walking training. Heart rate (HR) variability (HRV) and baroreflex sensitivity (BRS) were measured at rest and 20 min after a 20 min bout of treadmill exercise at 65% VO2 peak in obese women with (n = 8) and without T2D (n = 12) before and after training. HRV was analyzed by frequency-domain [high- (HF) power and low-frequency (LF)] and BRS by the sequence method. Exercise training induced similar significant changes in VO2 peak, resting systolic blood pressure (SBP) and post-exercise autonomic function in both groups. Training increased VO2 peak (6%; P < 0.01) and decreased resting SBP (8%; P < 0.001). Increased post-exercise HR recovery (5%; P < 0.001), HF power (14%; P < 0.05), LF power (14%; P < 0.05) and BRS (86%; P < 0.001) were also observed. Resting autonomic function and post-exercise SBP were not altered after training. In conclusion, endurance training reduced blood pressure without changes in HRV and BRS at rest, but training increased HRV and BRS during the recovery of acute endurance exercise indicating an improved post-exercise autonomic modulation of HR, which was similar in obese women with and without T2D.

Medicine and Science in Sports and Exercise, 2004

Purpose: This study established the published prediction equations for the energy expenditure of ... more Purpose: This study established the published prediction equations for the energy expenditure of walking and running compared with the measured values. To make this comparison we first determined whether differences exist in energy expenditure for 1600 m of walking versus running, and whether energy expenditure differences occur due to being on the track or treadmill. Methods: Energy was measured via indirect calorimetry in 24 subjects while walking (1.41 m·s Ϫ1 ) and running (2.82 m·s Ϫ1 ) 1600 m on the treadmill. A subgroup also performed the 1600-m run/walk on the track. The measured energy expenditures were compared with published prediction equations. Results: Running required more energy (P Ͻ 0.01) for 1600 m than walking (treadmill: running 481 Ϯ 20.0 kJ, walking 340 Ϯ 14 kJ; track: running 480 Ϯ 23 kJ, walking 334 Ϯ 14 kJ) on both the track and treadmill. Predictions using the ACSM or Léger equations for running, and the Pandolf equation for walking, were similar to the actual energy expenditures for running and walking (total error: ACSM: Ϫ20 and 14.4 kJ, respectively; Légers walking: Ϫ10.1 kJ; Pandolf walking: Ϫ10.0 kJ). An overestimation (P Ͻ 0.01) for 1600 m was found with the McArdle's table for walking and running energy expenditure and with van der Walt's prediction for walking energy expenditure, whereas the Epstein equation underestimated running energy expenditure (P Ͻ 0.01). Conclusion: Running has a greater energy cost than walking on both the track and treadmill. For running, the Léger equation and ACSM prediction model appear to be the most suitable for the prediction of running energy expenditure. The ACSM and Pandolf prediction equation also closely predict walking energy expenditure, whereas the McArdle's table or the equations by Epstein and van der Walt were not as strong predictors of energy expenditure.

American Journal on Mental Retardation, 2006