Publications (52) View all
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Article: Influence of running stride frequency in heart rate variability analysis during treadmill exercise testing.
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ABSTRACT: The analysis and interpretation of heart rate variability (HRV) during exercise is challenging not only because of the non-stationary nature of exercise, the time-varying mean heart rate and the fact that respiratory frequency exceeds 0.4 Hz. There are also other factors, such as the component centred at the pedalling frequency observed in maximal cycling tests, which may confuse the interpretation of HRV analysis. The objectives of this study are to test the hypothesis that a component centred at the running stride frequency appears in the HRV of subjects during maximal treadmill exercise testing, and to study its influence in the interpretation of the low frequency (LF) and high frequency (HF) components of HRV during exercise. The HRV of 23 subjects during maximal treadmill exercise testing is analyzed. The instantaneous power of different HRV components is computed from the smoothed pseudo Wigner-Ville distribution of the modulating signal assumed to carry information from the autonomic nervous system, which is estimated based on the time-varying integral pulse frequency modulation model. Besides the LF and HF components, the appearance is revealed of a component centred at the running stride frequency as well as its aliases. The power associated with the stride frequency component and its aliases represents 22±7% (median±median absolute deviation) of the total HRV power in all the subjects. Normalized LF power decreases as the exercise intensity increases, while normalized HF power increases. The power associated with the stride frequency does not change significantly with exercise intensity. Consideration of the running stride frequency component and its aliases is very important in HRV analysis since stride frequency aliases may overlap with LF and HF components.IEEE transactions on bio-medical engineering 01/2013; · 2.15 Impact Factor -
Article: Fat mass influence on bone mass is mediated by the independent association between lean mass and bone mass among elderly women: A cross-sectional study.
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ABSTRACT: OBJECTIVES: To study the independent association of fat mass (FM) and lean mass (LM) with bone mass and to study the differences in bone mass by weight and fat status in 223 seniors (aged 65-89 years) from the city of Zaragoza (Spain), after controlling for age, height, physical activity (PA) and LM. STUDY DESIGN: Cross-sectional study. MAIN OUTCOME MEASURES: LM, FM, bone mineral content (BMC) and density (BMD) were measured with dual energy X-ray absortiometry. The relationships of FM and LM with bone-related variables (subtotal body, hip, femoral neck and lumbar spine) were analyzed by linear regression and differences between weight and fat status were analyzed by one-way analysis of covariance. RESULTS: In men, there were no significant associations between FM and BMC or BMD. In women FM was positively associated with bone-related variables after adjustment for age, height and PA, whereas adjustment for LM removed all these significant associations. Overweight/obese elderly women had higher BMC and BMD than their non-overweight peers in all regions studied. Additional adjustment for PA did not change the differences between weight status groups, while adjusting for LM removed some of the associations. Overfat/obese men and women did not show higher levels of bone mass than their non-overfat peers. LM was positively associated with bone variables in both sexes. Additional adjustment for PA and FM did not alter the results. CONCLUSION: The association between fat mass and bone mass of elderly women is mediated by the independent association between lean mass and bone mass.Maturitas 10/2012; · 2.77 Impact Factor -
Article: Cortical and trabecular bone at the radius and tibia in male and female adolescents with Down syndrome: a peripheral quantitative computed tomography (pQCT) study.
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ABSTRACT: We aimed to describe the structure and strength of the tibia and radius of adolescents with Down syndrome. We observed that despite higher levels of volumetric bone mineral density in determined skeletal sites, they are at higher risk of developing osteoporotic fractures in the future due to their lower bone strength indexes. INTRODUCTION: The aims of the study were to describe the cortical and trabecular volumetric bone mineral density (vBMD), bone mineral content (BMC), area, and bone strength in adolescents with Down syndrome (DS) and to compare them with adolescents without disabilities. METHODS: Thirty adolescents (11 girls) with DS and 28 without disabilities (10 girls) participated in the study. Peripheral quantitative computed tomography measurements were taken at proximal and distal sites of the tibia and radius. Values of total, trabecular, and cortical BMC; vBMD; and area were obtained of each scan. Cortical thickness and endosteal and periosteal circumferences were also measured, and different bone strength indexes were calculated. Student's t tests were applied between groups. RESULTS: The DS group showed greater vBMD at distal radius, BMC at proximal radius, and total and cortical vBMD at proximal tibia. The non-DS group showed higher total and trabecular area at the distal radius and total, cortical, and trabecular BMC and area at distal tibia. Higher values of periosteal and endosteal circumference and bone strength were also found in non-DS group. CONCLUSIONS: From these results, it can be believed that even with higher vBMD in determined skeletal sites, adolescents with DS are at higher risk of suffering bone fractures due to an increased fragility by lower resistance to load bending or torsion.Osteoporosis International 06/2012; · 4.58 Impact Factor -
Article: [Increased risk of obesity and central obesity in sedentary postmenopausal women].
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ABSTRACT: Aims: To establish the influence of a sedentary behavior (sit time) on body composition in elderly women from Aragón. Methods: A total of 457 women participated in the study. Hours of walking were used to define the active behavior (> 1 vs. < 1 h/day) and hours of sitting were used to establish the sedentary behavior (> 4 vs. < 4 h/day). Anthropometric evaluation was conducted following the ISAK recommendations. Fat mass was estimated through electrical bio-impedance. Differences between groups were analyzed by ANOVA and logistic regression analysis was used to study the association between active and sedentary behaviors with body composition. Results: The sedentary group had higher weight, BMI, waist circumference and fat mass than the non-sedentary group (all p < 0.05). In addition, those women who sat more than 4 h/day had 1.7, 2.7 and 1.7-fold higher odds ratio for having overweight, obesity and central obesity, respectively, regardless of the hours of walking (95% IC [1.006-2.739]; [1.518-4.491] y [1.154-2.565]). When activity and sedentary levels were studied together, active and sedentary women were 2.0 times more likely to be overweight (95% CI [0.995-3.961]), 4.4 to be obese (95% CI [2.101-9.264]) and 2.3 for having central obesity (95% CI [1.329-3.939]) than women with an active and non-sedentary behavior. Conclusion: Being sitting more than 4 hours a day increases the risk of overweight, obesity and central obesity, regardless of the hours of walking in postmenopausal women.Nutricion hospitalaria: organo oficial de la Sociedad Espanola de Nutricion Parenteral y Enteral 06/2012; 27(3):865-70. · 1.12 Impact Factor -
Article: Effects of whole body vibration training on body composition in adolescents with Down syndrome.
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ABSTRACT: The present study aimed to determine the effect of 20 weeks of whole body vibration (WBV) on the body composition of adolescents with Down syndrome (DS). Thirty adolescent with DS were divided into two groups: control and WBV. Whole body, upper and lower limbs body fat and lean body mass were measured with dual energy X-ray absorptiometry (DXA) before and after 20 weeks of WBV training. Repeated measures of ANOVA adjusting by height, weight and Tanner stage were used to analyze possible group by time interactions on body composition. The adjusted percentages of change in body composition were also compared between control and WBV groups. No group by time interactions were found for any variable, but the WBV group showed a higher reduction in body fat at the upper limbs (p<0.05), and a tendency toward higher percent increase in whole body lean body mass. Overall, a 20-week WBV training is not enough by itself for increasing lean body mass in adolescents with DS, but it might be helpful for improving body composition in this population. Its relationship with health and autonomy enhances the importance of these results.Research in developmental disabilities 03/2013; 34(5):1426-1433. · 4.41 Impact Factor
