Biomedical subjects

A Sparti

Publications and source records attributed to A Sparti.

8 recordsLinked to original sources

PubMed1999

The prediction of speed and incline in outdoor running in humans using accelerometry.

PURPOSE: To explore whether triaxial accelerometric measurements can be utilized to accurately assess speed and incline of running in free-living conditions. METHODS: Body accelerations during running were recorded at the lower back and at the heel by a portable data logger in 20 human subjects, 10 men, and 10 women. After parameterizing body accelerations, two neural networks were designed to recognize each running pattern and calculate speed and incline. Each subject ran 18 times on outdoor roads at various speeds and inclines; 12 runs were used to calibrate the neural networks whereas the 6 other runs were used to validate the model. RESULTS: A small difference between the estimated and the actual values was observed: the square root of the mean square error (RMSE) was 0.12 m x s(-1) for speed and 0.014 radiant (rad) (or 1.4% in absolute value) for incline. Multiple regression analysis allowed accurate prediction of speed (RMSE = 0.14 m x s(-1)) but not of incline (RMSE = 0.026 rad or 2.6% slope). CONCLUSION: Triaxial accelerometric measurements allows an accurate estimation of speed of running and incline of terrain (the latter with more uncertainty). This will permit the validation of the energetic results generated on the treadmill as applied to more physiological unconstrained running conditions.

Analysis of Variance↗

PubMed1998

Data-based approach for developing a physical activity frequency questionnaire.

Measurement of total energy expenditure may be crucial to an understanding of the relation between physical activity and disease and in order to frame public health intervention. To devise a self-administered physical activity frequency questionnaire (PAFQ), the following data-based approach was used. A 24-hour recall was administered to a random sample of 919 adult residents of Geneva, Switzerland. The data obtained were used to establish the list of activities (and their median duration) that contributed to 95% of the energy expended, separately for men and women. Activities that were trivial for the whole sample but that contributed to > or = 10% of an individual's energy expenditure were also selected. The final PAFQ lists 70 activities or group of activities with their typical duration. About 20 minutes are required for respondents to indicate the number of days and the number of hours per day that they performed each activity. The PAFQ method was validated against a heart rate monitor, a more objective method. The total energy estimated by the PAFQ in 41 volunteers correlated well (r = 0.76) with estimates using a heart rate monitor. The authors conclude that the design of their self-administered physical activity frequency questionnaire based on data from 24-hour recall appeared to accurately estimate energy expenditure.

Adult↗

PubMed1997

Relationship between resting metabolic rate and the composition of the fat-free mass.

Although a low resting metabolic rate (RMR) has been shown to be a risk factor for future weight gain, little is known about the mechanisms determining its level. We tested the hypothesis that the composition of the fat-free mass (FFM) is a main determinant of RMR. If this hypothesis is true, a regression model including internal organ masses as independent variables should explain a larger fraction of the variance in RMR than is explained using only FFM as a predictor. We measured fat mass by hydrodensitometry, liver and kidney volumes by computed tomography (CT), heart mass by echocardiography, muscle mass by dual-energy x-ray absorptiometry (DEXA), and RMR by calorimetry in 40 subjects. FFM and fat mass explained 83% of the variability in RMR (standard error of the estimate [SEE], 420 kJ/d) in a multiple regression analysis. Combinations of organ and muscle masses performed as well as but not better than stepwise multiple regression models. The fact that the composition of the lean mass could not improve the prediction of RMR in comparison to the traditional FFM-fat mass model suggests that the weight of internal organs is not a main determinant of RMR. This may indicate that the variability in RMR is associated with variation in energy expenditure per kilogram of tissue of the individual organs.

Adipose Tissue↗

PubMed1997

Ad libitum intake of a high-carbohydrate or high-fat diet in young men: effects on nutrient balances.

The effect of diet composition [high-carbohydrate, low-fat (HC) and high-fat, low-carbohydrate (HF) diets] on macronutrient intakes and nutrient balances was investigated in young men of normal body weight. Eleven subjects were studied on two occasions for 48 h in a whole-body indirect calorimeter in a crossover design. Subjects selected their meals from a list containing a large variety of common food, which had a food quotient > 0.85 for the HC diet and < 0.85 for the HF diet. The average ad libitum intake was 14.41 +/- 0.85 MJ/d (67%, 18%, and 15% of energy as carbohydrate, fat, and protein, respectively) with the HC diet and 18.25 +/- 0.90 MJ/d (26%, 61%, and 13% of energy as carbohydrate, fat, and protein, respectively) with the HF diet. Total energy expenditure was not significantly influenced by diet composition: 10.46 +/- 0.27 and 10.97 +/- 0.22 MJ/d for the HC and HF diets, respectively. During the 2 test days, cumulative carbohydrate storage was 418 +/- 72 and 205 +/- 47 g, and fat balance was 29 +/- 17 and 291 +/- 29 g with the HC and HF diets, respectively. Only the HF diet induced a significantly positive fat balance. These results emphasize the important role of the dietary fat content in body fat storage.

Adult↗

PubMed1997

Effect of an acute reduction in carbohydrate intake on subsequent food intake in healthy men.

We investigated the effect of a combined carbohydrate and energy deficit in the regulation of food intake during 1 d. Seven lean, male subjects were studied in a crossover design. After 7 d of consuming a baseline diet (40% of energy as fat, 45% as carbohydrate, and 15% as protein), subjects were deprived of carbohydrate for 24 h; baseline amounts of fat and protein were consumed but only one-third of the baseline amount of carbohydrate. On the following outcome day, subjects were free to select ad libitum from a selection of either high-carbohydrate or low-carbohydrate food. On the baseline diet subjects consumed on average 10.9 +/- 1.7 MJ/d (carbohydrate: 305 +/- 49 g/d; fat: 116 +/- 18 g/d) and there was no difference in baseline intake between the two phases of the crossover study. During the deficit day, intake was reduced to 7.7 +/- 1.2 MJ/d [carbohydrate: 110 +/- 25 g/d (66% reduction); fat: 116 +/- 18 g/d]. On the outcome day, energy intake from high-carbohydrate foods was on average 10.5 MJ/d (carbohydrate: 430 +/- 112 g/d; fat: 48 +/- 20 g/d) compared with 16.6 MJ/d from high-fat foods (carbohydrate: 312 +/- 84 g/d; fat: 258 +/- 78 g/d). We conclude that the restoration of an energy deficit is not the main factor determining acute food intake. Rather, the data support the hypothesis that, under the conditions of our experiment, the intake of carbohydrate required to maintain carbohydrate balance was a more important factor in the regulation of acute food intake than was the restoration of energy deficit is not.

Adult↗

PubMed1996

Autonomic activity assessed by heart rate spectral analysis varies with fat distribution in obese women.

Obesity in humans has been associated with altered autonomic nervous system activity. The objective of this study was to examine the relationship between autonomic function and body fat distribution in 16 obese, postmenopausal women using power spectrum analysis of heart rate variability. Using this technique, a low frequency peak (0.04-0.12 Hz) reflecting mixed sympathetic and parasympathetic activity, and a high frequency peak (0.22-0.28 Hz) reflecting parasympathetic activity, were identified from 5-minute consecutive heart rate data (both supine and standing). Autonomic activity in upper body (UBO) vs. lower body obesity (LBO)(by waist-to-hip ratio) and subcutaneous vs. visceral obesity (by CT scan) was evaluated. Power spectrum data were log transformed to normalize the data. The results showed that standing, low-frequency power (reflecting sympathetic activity) and supine, high-frequency power (reflecting parasympathetic activity) were significantly greater in UBO than in LBO, and in visceral compared to subcutaneous obesity. Women with combined UBO and visceral obesity had significantly higher cardiac sympathetic and parasympathetic activity than any other subgroup. We conclude that cardiac autonomic function as assessed by heart rate spectral analysis varies in women depending on their regional body fat distribution.

Adipose Tissue↗

PubMed1992

Effect of diet on glucose tolerance 36 hours after glycogen-depleting exercise.

In order to estimate the effect of muscle glycogen content on the glycaemic response, glucose tolerance and glucose oxidation were measured in eight healthy male subjects. Each subject followed three different treatments, consisting of either a physical exercise session followed by 36 h of a low-carbohydrate high-fat diet (glycogen depletion treatment); or a physical exercise followed by 36 h of a high carbohydrate diet (glycogen repletion treatment); or a low-carbohydrate high-fat diet alone (diet treatment). After both the glycogen depletion and the diet treatments, the subjects showed a high glycaemic response (443 +/- 57 and 419 +/- 63 mmol.min/l resp.), a high insulinaemic response (7158 +/- 671 and 7643 +/- 913 mU.min/l), and a low rate of glucose oxidation (27.5 +/- 2.4 and 31.0 +/- 5.8 g/3 h respiration). In contrast, after the glycogen repletion treatment, the subjects had a lower glycaemic response (197 +/- 21 mmol.min/l), a lower insulinaemic response (4645 +/- 327 mU.min/l) and a higher glucose oxidation level (47.4 +/- 2.0 g/3h). Fasting free fatty acids (FFA) were positively correlated with glucose area (P less than 0.001) and negatively with glucose oxidation (P less than 0.01). These results show a strong inhibitory effect of the low-carbohydrate high-fat diet on glucose tolerance despite prior strenuous exercise. Because of this, the effect of the muscle glycogen content could not be tested. However, the results suggest that the FFA/glucose interrelationship may override exercise-induced changes in insulin-stimulated glucose uptake.

Adult↗

PubMed1989

Basal rate of metabolism and temperature regulation in Sorex coronatus and S. minutus (Soricidae: Mammalia).

1. The basal rate of metabolism (BMR), body temperature and thermal conductance of Sorex minutus and Sorex coronatus were studied. Special attention was given to measuring BMR in resting and postabsorptive shrews. 2. Both species exhibit a high BMR, respectively 339 and 289% of the value expected on the basis of body mass. 3. The thermal conductance of both species is similar to the predicted value and their body temperature averages 38.6 and 37.6 degrees C respectively. 4. Available data suggest that a very high BMR may be a common feature within the genus Sorex.

Animals↗