Biomedical subjects

S Carrasco Sosa

Publications and source records attributed to S Carrasco Sosa.

4 recordsLinked to original sources

PubMed1992

Densitometric validation of nine anthropometric prediction equations of body composition in young native men of Mexico City.

Body density by hydrostatic method and anthropometric variables were measured in 29 young males, natives of Mexico City, in order to test the validity of nine currently used equations for predicting body composition. Tested equations were those reported for body density by Sloan, Wilmore, Jackson and Pollock, Durnin and Womersley, Lohman, and Pollock et al.; for lean body weight by Wilmore, and Hume-Rathbun; and for fat percentage by Yuhasz. Mean values for body density, fat percentage and lean body weight obtained by hydrostatic weighing were 1.0560 +/- 0.0149 kg/l, 18.9 +/- 6.7%, and 52.6 +/- 5.3 kg, respectively, while the means for predicted body density using the six regression equations varied from 1.0538 to 1.0654 kg/l, with a range of correlation from 0.846 to 0.900, and total errors from 0.0077 to 0.0124 kg/l. Mean lean body weight predicted by Wilmore was 55.7 +/- 5.9 kg, with an R of 0.902 and a total error of 4.0 kg, while values given in the same order by Hume-Rathbun were 52.8 +/- 4.8 kg, R of 0.892 and total error of 2.3 kg. Mean fat percentage predicted by Yuhasz was 17.8 +/- 5.6%, R of 0.869 and total error of 3.5%. Although by analysis of variance there were no significant differences among the means of the models, statistical analysis of individual differences between predicted and measured values were significant in six of them.(ABSTRACT TRUNCATED AT 250 WORDS)

Adipose Tissue↗

PubMedDate not supplied

The effects of body position, controlled breathing and exercise on the heart rate variability parameters in healthy subjects.

The behavior of temporal and spectral parameters of the heart rate variability was determined during 5 different maneuvers in order to characterize the level of sympathetic-vagal activity. The discriminating capacity of two spectral parameter estimation schemes were compared, and the respiratory influence was evaluated. One hundred and ten records of instantaneous heart rate and respiratory amplitude were analyzed, both in temporal and spectral perspectives. The records were obtained from 22 healthy subjects, under a five-stage protocol: supine, controlled breathing, standing, exercise, and recovery. A discriminating and characteristic behavior was found among the maneuvers, specifically for the dispersion parameters, low and intermediate partial components. The two integration-normalization procedures used in the estimation of the spectral components showed similarities, producing a functional interpretation independent of the selected procedure. The division of the low frequency component in two separate bands, allowed an improved discriminating capacity. The respiration had an important influence in the controlled breathing maneuver while being lower in the rest of the stages. In conclusion, the maneuvers determined a typical behavior of the dispersion and spectral parameters (low and intermediate partial components) of the heart rate variability, showing adequate distinctive levels in the sympathetic-vagal activity for each maneuver.

Adult↗

PubMedDate not supplied

[Direct and indirect maximum oxygen consumption in sedentary subjects living at a moderate altitude].

In order to compare 1) predicted values of aerobic capacity (VO2Max) and, 2) direct VO2Max reported in the literature for sedentary subjects, direct VO2Max was measured in 27 sedentary males (18-25 years old), residents at 2240 meters (588.5 +/- 1.0 mmHg). To get direct VO2Max, ventilation and expired gases were measured while the subjects performed maximal exercise on a motor treadmill. Predicted VO2Max was estimated from the Astrand and Ryhming nomogram by measuring submaximal heart rate (HR) during a step test protocol. The mean results from the maximal protocol were: HR 194.9 +/- 5.4 beats/min, direct VO2Max 3.15 +/- 0.46 L/min and 47.67 +/- 5.07 ml/min/Kg, absolute and relative to body weight, respectively. From the submaximal protocol, mean HR was 171 +/- 8.3 beats/min and predicted VO2Max 2.50 +/- 0.39 L/min. In spite of a good correlation (r = 0.79) between predicted and direct VO2Max, the predicted values underestimated 20.3 +/- 7.2% direct measurements. Our data point out that 1) indirect measuring of aerobic capacity from the Astrand and Ryhming nomogram is discouraged in sedentary subjects living at moderate altitudes and, 2) in contrast to other author's suggestions, aerobic capacity is not diminished by chronic exposure to moderate hypoxia.

Adolescent↗

PubMedDate not supplied

[Left ventricular function in physically active and sedentary subjects during physical exercise].

An exercise program based on growing intensity loads (50 watts) was applied to 21 healthy, middle-aged subjects, who were divided into two groups: the physically actives and the sedentaries, according to their physical activity habits. During exercise, which was made on a treadmill, the following variables were measured: oxygen intake (VO2), cardiac frequency (FC), left ventricule ejection time (TEVI), maximal value of the first derivative of ear ensitogram (VMPDDO) and indirect arterial pressure. The active group reached higher values of power and VO2 (absolute and by pulse) and lower values of FC at under maximal works; these data therefore show their best cardiopulmonary capacity. The TEVI in the active group was higher at 150 watts because of the lower FC presented by its assigned subjects. For a maximal exercise condition, both groups had similar ejection times, but the reduction rate of actives' TEVI decreased, which in turn indicates the handling of higher stroke volumes. The VMPDDO relation with the successive increments of work loads was non linear. This index had higher values in the active group, for an exercise strength over 100 watts; this fact allowed the statistical differentiation of both groups. Accordingly, the VMPDDO did indicate the higher left ventricular function of the active subjects during exercise; this findings supports the notion which establishes that resistance training enhances myocardial contraction. In the recovery stage, the sedentaries' VMPDDO increases in a significant way, due to a possible mechanism as to hold stroke volume. In conclusion, the active subjects heart is a more efficient pump than the sedentaries', because of its capacity to handle under maximal exercise higher stroke volumes in the same ejection time, and thus in a higher ejection rate, with equal cardiac frequencies arterial pressures and myocardial oxygen intake.

Adult↗