Yves Schutz

Fat-free mass index and fat mass index percentiles in Caucasians aged 18-98 y.

Objective: To determine reference values for fat-free mass index (FFMI) and fat mass index (FMI) in a large Caucasian group of apparently healthy subjects, as a function of age and gender and to develop percentile distribution for these two parameters.Design: Cross-sectional study in which bioelectrical impedance analysis (50 kHz) was measured (using tetrapolar electrodes and cross-validated formulae by dual-energy X-ray absorptiometry in order to calculate FFMI (fat-free mass/height squared) and FMI (fat mass/height squared).Subjects: A total of 5635 apparently healthy adults from a mixed non-randomly selected Caucasian population in Switzerland (2986 men and 2649 women), varying in age from 24 to 98 y.Results: The median FFMI (18–34 y) were 18.9 kg/m2 in young males and 15.4 kg/m2 in young females. No difference with age in males and a modest increase in females were observed. The median FMI was 4.0 kg/m2 in males and 5.5 kg/m2 in females. From young to elderly age categories, FMI progressively rose by an average of 55% in males and 62% in females, compared to an increase in body mass index (BMI) of 9 and 19% respectively.Conclusions: Reference intervals for FFMI and FMI could be of practical value for the clinical evaluation of a deficit in fat-free mass with or without excess fat mass (sarcopenic obesity) for a given age category, complementing the classical concept of body mass index (BMI) in a more qualitative manner. In contrast to BMI, similar reference ranges seems to be utilizable for FFMI with advancing age, in particular in men.

The use of uniaxial accelerometry for the assessment of physical-activity-related energy expenditure: a validation study against whole-body indirect calorimetry.

Assessing the total energy expenditure (TEE) and the levels of physical activity in free-living conditions with non-invasive techniques remains a challenge. The purpose of the present study was to investigate the accuracy of a new uniaxial accelerometer for assessing TEE and physical-activity-related energy expenditure (PAEE) over a 24 h period in a respiratory chamber, and to establish activity levels based on the accelerometry ranges corresponding to the operationally defined metabolic equivalent (MET) categories. In study 1, measurement of the 24 h energy expenditure of seventy-nine Japanese subjects (40 (SD 12) years old) was performed in a large respiratory chamber. During the measurements, the subjects wore a uniaxial accelerometer (Lifecorder; Suzuken Co. Ltd, Nagoya, Japan) on their belt. Two moderate walking exercises of 30 min each were performed on a horizontal treadmill. In study 2, ten male subjects walked at six different speeds and ran at three different speeds on a treadmill for 4 min, with the same accelerometer. O2 consumption was measured during the last minute of each stage and was expressed in MET. The measured TEE was 8447 (SD 1337) kJ/d. The accelerometer significantly underestimated TEE and PAEE (91.9 (SD 5.4) and 92.7 (SD 17.8) % chamber value respectively); however, there was a significant correlation between the two values (r 0.928 and 0.564 respectively; P<0.001). There was a strong correlation between the activity levels and the measured MET while walking (r(2) 0.93; P<0.001). Although TEE and PAEE were systematically underestimated during the 24 h period, the accelerometer assessed energy expenditure well during both the exercise period and the non-structured activities. Individual calibration factors may help to improve the accuracy of TEE estimation, but the average calibration factor for the group is probably sufficient for epidemiological research. This method is also important for assessing the diurnal profile of physical activity.

Increased 24-Hour Energy Expenditure in Cigarette Smokers

Abstract We studied the effect of smoking on energy expenditure in eight healthy cigarette smokers who spent 24 hours in a metabolic chamber on two occasions, once without smoking and once while smoking 24 cigarettes per day. Diet and physical exercise (30 minutes of treadmill walking) were standardized on both occasions. Physical activity in the chamber was measured by use of a radar system. Smoking caused an increase in total 24-hour energy expenditure (from a mean value [±SEM] of 2230±115 to 2445±120 kcal per 24 hours; P<0.001), although no changes were observed in physical activity or mean basal metabolic rate (1545±80 vs. 1570±70 kcal per 24 hours). During the smoking period, the mean diurnal urinary excretion of norepinephrine (±SEM) increased from 1.25±0.14 to 1.82±0.28 μg per hour (P<0.025), and mean nocturnal excretion increased from 0.73±0.07 to 0.91±0.08 μg per hour (P<0.001). These short-term observations demonstrate that cigarette smoking increases 24-hour energy expenditure by approximately ...

Management of Obesity in Adults: European Clinical Practice Guidelines

The development of consensus guidelines for obesity is complex. It involves recommending both treatment interventions and interventions related to screening and prevention. With so many publications and claims, and with the awareness that success for the individual is short-lived, many find it difficult to know what action is appropriate in the management of obesity. Furthermore, the significant variation in existing service provision both within countries as well as across the regions of Europe makes a standardised approach, even if evidence-based, difficult to implement. In formulating these guidelines, we have attempted to use an evidence-based approach while allowing flexibility for the practicing clinician in domains where evidence is currently lacking and ensuring that in treatment there is recognition of clinical judgment and of regional diversity as well as the necessity of an agreed approach by the individual and family. We conclude that i) physicians have a responsibility to recognise obesity as a disease and help obese patients with appropriate prevention and treatment, ii) treatment should be based on good clinical care and evidence-based interventions and iii) obesity treatment should focus on realistic goals and lifelong management.

Body composition interpretation. Contributions of the fat-free mass index and the body fat mass index.

OBJECTIVE Low and high body mass index (BMI) values have been shown to increase health risks and mortality and result in variations in fat-free mass (FFM) and body fat mass (BF). Currently, there are no published ranges for a fat-free mass index (FFMI; kg/m(2)), a body fat mass index (BFMI; kg/m(2)), and percentage of body fat (%BF). The purpose of this population study was to determine predicted FFMI and BFMI values in subjects with low, normal, overweight, and obese BMI. METHODS FFM and BF were determined in 2986 healthy white men and 2649 white women, age 15 to 98 y, by a previously validated 50-kHz bioelectrical impedance analysis equation. FFMI, BFMI, and %BF were calculated. RESULTS FFMI values were 16.7 to 19.8 kg/m(2) for men and 14.6 to 16.8 kg/m(2) for women within the normal BMI ranges. BFMI values were 1.8 to 5.2 kg/m(2) for men and 3.9 to 8.2 kg/m(2) for women within the normal BMI ranges. BFMI values were 8.3 and 11.8 kg/m(2) in men and women, respectively, for obese BMI (>30 kg/m(2)). Normal ranges for %BF were 13.4 to 21.7 and 24.6 to 33.2 for men and women, respectively. CONCLUSION BMI alone cannot provide information about the respective contribution of FFM or fat mass to body weight. This study presents FFMI and BFMI values that correspond to low, normal, overweight, and obese BMIs. FFMI and BFMI provide information about body compartments, regardless of height.

The Effect of Ethanol on Fat Storage in Healthy Subjects

BACKGROUND Ethanol can account for up to 10 percent of the energy intake of persons who consume moderate amounts of ethanol. Its effect on energy metabolism, however, is not known. METHODS We studied the effect of ethanol on 24-hour substrate-oxidation rates in eight normal men during two 48-hour sessions in an indirect-calorimetry chamber. In each session, the first 24 hours served as the control period. On the second day of one session, an additional 25 percent of the total energy requirement was added as ethanol (mean [+/- SD], 96 +/- 4 g per day); during the other session, 25 percent of the total energy requirement was replaced by ethanol, which was isocalorically substituted for lipids and carbohydrates. RESULTS Both the addition of ethanol and the isocaloric substitution of ethanol for other foods reduced 24-hour lipid oxidation. The respective mean (+/- SE) decreases were 49.4 +/- 6.7 and 44.1 +/- 9.3 g per day (i.e., reductions of 36 +/- 3 percent and 31 +/- 7 percent from the oxidation rate during the control day; P less than 0.001 and P less than 0.0025). This effect occurred only during the daytime period (8:30 a.m. to 11:30 p.m.), when ethanol was consumed and metabolized. Neither the addition of ethanol to the diet nor the isocaloric substitution of ethanol for other foods significantly altered the oxidation of carbohydrate or protein. Both regimens including ethanol produced an increase in 24-hour energy expenditure (7 +/- 1 percent with the addition of ethanol, P less than 0.001; 4 +/- 1 percent with the substitution of ethanol for other energy sources, P less than 0.025). CONCLUSIONS Ethanol, either added to the diet or substituted for other foods, increases 24-hour energy expenditure and decreases lipid oxidation. Habitual consumption of ethanol in excess of energy needs probably favors lipid storage and weight gain.

A new accelerometric method to assess the daily walking practice

OBJECTIVE: To describe a method to obtain a profile of the duration and intensity (speed) of walking periods over 24 hours in women under free-living conditions.DESIGN: A new method based on accelerometry was designed for analyzing walking activity. In order to take into account inter-individual variability of acceleration, an individual calibration process was used. Different experiments were performed to highlight the variability of acceleration vs walking speed relationship, to analyze the speed prediction accuracy of the method, and to test the assessment of walking distance and duration over 24-h.SUBJECTS: Twenty-eight women were studied (mean±s.d.) age: 39.3±8.9 y; body mass: 79.7±11.1 kg; body height: 162.9±5.4 cm; and body mass index (BMI) 30.0±3.8 kg/m2.RESULTS: Accelerometer output was significantly correlated with speed during treadmill walking (r=0.95, P<0.01), and short unconstrained walks (r=0.86, P<0.01), although with a large inter-individual variation of the regression parameters. By using individual calibration, it was possible to predict walking speed on a standard urban circuit (predicted vs measured r=0.93, P<0.01, s.e.e.=0.51 km/h). In the free-living experiment, women spent on average 79.9±36.0 (range: 31.7–168.2) min/day in displacement activities, from which discontinuous short walking activities represented about 2/3 and continuous ones 1/3. Total walking distance averaged 2.1±1.2 (range: 0.4–4.7) km/day. It was performed at an average speed of 5.0±0.5 (range: 4.1–6.0) km/h.CONCLUSION: An accelerometer measuring the anteroposterior acceleration of the body can estimate walking speed together with the pattern, intensity and duration of daily walking activity.

Physical activity and pregnancy: cardiovascular adaptations, recommendations and pregnancy outcomes.

Regular physical activity is associated with improved physiological, metabolic and psychological parameters, and with reduced risk of morbidity and mortality. Current recommendations aimed at improving the health and wellbeing of nonpregnant subjects advise that an accumulation of ≥30 minutes of moderate physical activity should occur on most, if not all, days of the week.Regardless of the specific physiological changes induced by pregnancy, which are primarily developed to meet the increased metabolic demands of mother and fetus, pregnant women benefit from regular physical activity the same way as nonpregnant subjects.Changes in submaximal oxygen uptake (V̇O2) during pregnancy depend on the type of exercise performed. During maternal rest or submaximal weight-bearing exercise (e.g. walking, stepping, treadmill exercise), absolute maternal V̇O2 is significantly increased compared with the nonpregnant state. The magnitude of change is approximately proportional to maternal weight gain.When pregnant women perform submaximal weight-supported exercise on land (e.g. level cycling), the findings are contradictory. Some studies reported significantly increased absolute V̇O2, while many others reported unchanged or only slightly increased absolute V̇O2 compared with the nonpregnant state. The latter findings may be explained by the fact that the metabolic demand of cycle exercise is largely independent of the maternal body mass, resulting in no absolute V̇O2 alteration.Few studies that directly measured changes in maternal maximal V̇O2 (V̇O2max) showed no difference in the absolute V̇O2max between pregnant and nonpregnant subjects in cycling, swimming or weight-bearing exercise. Efficiency of work during exercise appears to be unchanged during pregnancy in non-weight-bearing exercise. During weight-bearing exercise, the work efficiency was shown to be improved in athletic women who continue exercising and those who stop exercising during pregnancy. When adjusted for weight gain, the increased efficiency is maintained throughout the pregnancy, with the improvement being greater in exercising women.Regular physical activity has been proven to result in marked benefits for mother and fetus. Maternal benefits include improved cardiovascular function, limited pregnancy weight gain, decreased musculoskeletal discomfort, reduced incidence of muscle cramps and lower limb oedema, mood stability, attenuation of gestational diabetes mellitus and gestational hypertension. Fetal benefits include decreased fat mass, improved stress tolerance, and advanced neurobehavioural maturation. In addition, few studies that have directly examined the effects of physical activity on labour and delivery indicate that, for women with normal pregnancies, physical activity is accompanied with shorter labour and decreased incidence of operative delivery.However, a substantial proportion of women stop exercising after they discover they are pregnant, and only few begin participating in exercise activities during pregnancy. The adoption or continuation of a sedentary lifestyle during pregnancy may contribute to the development of certain disorders such as hypertension, maternal and childhood obesity, gestational diabetes, dyspnoea, and pre-eclampsia. In view of the global epidemic of sedentary behaviour and obesity-related pathology, prenatal physical activity was shown to be useful for the prevention and treatment of these conditions. Further studies with larger sample sizes are required to confirm the association between physical activity and outcomes of labour and delivery.

Estimation of speed and incline of walking using neural network

A portable data logger is designed to record body accelerations during human walking. Five subjects walk first on a treadmill at various speeds on the level, and at positive and negative inclines. Then, the subjects performed a self-pace walking on an outdoor test circuit involving roads of various inclines. The recorded signals are parameterized, and the pattern of walking at each gait cycle is found. These patterns are presented to two neural networks which estimate the incline and the speed of walking. The results show a good estimation of the incline and the speed for all of the subjects. The correlation between predicted and actual inclines is r=0.98, and the maximum of speed-predicted error is 16%. To the best of our knowledge these results constitute the first speed and incline estimation of level and slope-unconstrained walking. >

Monitoring of Posture Allocations and Activities by a Shoe-Based Wearable Sensor

Monitoring of posture allocations and activities enables accurate estimation of energy expenditure and may aid in obesity prevention and treatment. At present, accurate devices rely on multiple sensors distributed on the body and thus may be too obtrusive for everyday use. This paper presents a novel wearable sensor, which is capable of very accurate recognition of common postures and activities. The patterns of heel acceleration and plantar pressure uniquely characterize postures and typical activities while requiring minimal preprocessing and no feature extraction. The shoe sensor was tested in nine adults performing sitting and standing postures and while walking, running, stair ascent/descent and cycling. Support vector machines (SVMs) were used for classification. A fourfold validation of a six-class subject-independent group model showed 95.2% average accuracy of posture/activity classification on full sensor set and over 98% on optimized sensor set. Using a combination of acceleration/pressure also enabled a pronounced reduction of the sampling frequency (25 to 1 Hz) with out significant loss of accuracy (98% versus 93%). Subjects had shoe sizes (US) M9.5-11 and W7-9 and body mass index from 18.1 to 39.4 kg/m2 and thus suggesting that the device can be used by individuals with varying anthropometric characteristics.