Valérie Julian

Nutritional compensation to exercise- vs. diet-induced acute energy deficit in adolescents with obesity

BACKGROUND To compare the energy and macronutrient intake responses to equivalent energy deficits induced by diet (food restriction) and exercise in adolescents with obesity. METHODS Fourteen 12-15years old obese adolescents completed three experimental conditions (08:00am to 07:30pm) in a randomized crossover design: i) control session (CON); ii) diet-induced 25% energy depletion (Def-EI), iii) and an exercise-induced 25% energy depletion (Def-EX). The sessions order was either CON/Def-EI/Def-EX or CON/Def-EX/Def-EI as the deficit corresponded to 25% of the energy ingested at lunch on the control day (CON) and was imposed either by exercise (Def-EX) or diet (Def-EI). Ad libitum EI and macronutrients preferences were assessed at dinner and appetite sensations assessed using visual analogue scales. RESULTS Mean BMI was 36.6±5.0kg/m2 (z-BMI: 2.40±0.29). The individually calibrated 25% energy deficit represented 254±92kcal. Ad libitum EI was significantly higher during both Def-EX (971±225kcal) and Def-EI (949±246kcal) compared with CON (742±297) (p<0.05). The relative energy ingested derived from fat was significantly higher on both Def-EX (36.6±10.9%) and Def-EI (36.9±13.1%) compared with CON (21.6±7.8%) (p<0.05). The energy derived from carbohydrates was significantly lower on both Def-EX (48.3±9.0%) and Def-EI (44.4±17.3%) compare with CON (61.1±10.1%) (p<0.05). Appetite sensations were not different between conditions. The induced energy deficit was negatively correlated with the ad libitum EI difference between the exercise and the control session (EI Def-EX - EI CON) (r=-0,643 p<0.05) and positively correlated with the EI difference between the dietary restriction and the control session (EI Def-EI - EI CON) (r=0,569 p<0.05). CONCLUSION Equicaloric exercise- or diet-induced energy deficits could lead to similar EI compensation in obese adolescents but this EI compensation might be influenced by the magnitude of the deficit.

Impact of a short early therapeutic education program on the quality of life of asthmatic children and their families

Few studies have been made on the impact of therapeutic education (TE) on the quality of life (QOL) of asthmatic primary‐school aged children. We attempted to assess the beneficial effects on the QOL of children and their parents of a short TE program initiated immediately after the first consultation with a pediatric pulmonologist.

A new equation based on the 6-min walking test to predict VO 2peak in women with obesity

Abstract Objective: The 6-min walking test (6 MWT) is commonly used to assess obese patients’ aerobic fitness, but it has rarely been compared with a direct measurement of maximal aerobic capacities (VO2max or VO2peak) in obese adults. The aim of this study was to investigate the relationship between the distance covered during a 6 MWT with objectively measured VO2peak and to propose a new equation to predict VO2peak from this walking test in obese patients. Methods: One hundred and thirty-seven obese patients (45.6 ± 12.5 years) admitted to our hospital for a multidisciplinary rehabilitation program were enrolled. After assessment of their body composition, the participants were asked to perform a 6 MWT and their maximal aerobic capacities (VO2peak) were measured. Result: There is a significant linear relation between VO2peak and the distance covered during the 6 MWT (p < 0.001; r = 0.349). The determinant of VO2peak was body mass index, waist-to-hip ratio, fat free mass, leading to the follow prediction equation VO2peak such as VO2peak (l/min) = (body mass index ×0.0150065) − (waist-to-hip-ratio × 0.8595088) + (fat-free-mass × 0.0295478) + (6-min walk test ×0.0020672) − 0.5853372. Conclusion: The 6-min walk test is a reliable method to reflect obese women’s aerobic capacities and the distance covered can be used to accurately estimate VO2peak according to our newly proposed equation. Implication for rehabilitation Obesity is a worldwide disease and physical capacity evaluation is a key point for rehabilitation. The six minutes’ walk test is commonly used in obese people to assess aerobic fitness. This study proposes a new equation using 6 MWT performance to estimate VO2peak.

Improving Peripheral and Central Vascular Adjustments during Exercise through a Training Program in Adolescents with Obesity

Objective: The effects of a training program (TP) on muscle microvascularization during exercise remained to be explored in adolescents with obesity. We hypothesized that a TP would lead to better microvascular adaptations to exercise in skeletal muscle. Methods: 15 inactive adolescents followed a 12-week TP where both peripheral (muscular microvascularization) and central (cardiac) adaptations to exercise (40 min exercise set at 70% V̇O2peak) were assessed before and after intervention. Microvascular adaptations were evaluated in the Musculus vastus lateralis with near-infrared spectroscopy, by measurement of muscular blood volume (IR-BV) and tissue oxygen saturation (IR-SO2). Central adaptations were evaluated using thoracic impedance. Results: The TP favored lower BMI (p < 0.001), lower total and abdominal fat (p < 0.001), and a trend for the decrease in insulin resistance index (p = 0.07). V̇O2peak relative to weight (p = 0.008) and maximum power output increased (p = 0.0003). A smaller initial drop in IR-BV and IR-SO2 (p < 0.001), a prompter return of these parameters to their base values, and a higher IR-BV and IR-SO2 all times taken together (p < 0.001) were observed after completing the TP. Concerning central adaptation, cardiac output decreased (p < 0.001). Conclusion: We demonstrate for the first time by noninvasive techniques that a training program induces peripheral and central vascular adaptations to exercise in adolescents with obesity.

Eccentric cycling is more efficient in reducing fat mass than concentric cycling in adolescents with obesity: XXXX

The benefits of eccentric (ECC) training on fat mass (FM) remain underexplored. We hypothesized that in obese adolescents, ECC cycling training is more efficient for decreasing whole‐body FM percentage compared to concentric (CON) performed at the same oxygen consumption (VO2). Twenty‐four adolescents aged 13.4 ± 1.3 years (BMI > 90th percentile) were randomized to ECC or CON. They performed three cyclo‐ergometer sessions per week (30 min per session) for 12 weeks: two habituation, 5 at 50% VO2peak, and 5 at 70% VO2peak. Anthropometric measurements, body composition, maximal incremental CON tests, strength tests, and blood samples were assessed pre‐ and post‐training. Whole‐body FM percentage decreased significantly after compared to pretraining in both groups, though to a larger extent in the ECC group (ECC: −10% vs CON: −4.2%, P < 0.05). Whole‐body lean mass (LM) percentage increased significantly in both groups after compared to pretraining, with a greater increase in the ECC group (ECC: 3.8% vs CON: 1.5%, P <0.05). The improvements in leg FM and LM percentages were greater in the ECC group (−6.5% and 3.0%, P = 0.01 and P < 0.01). Quadriceps isometric and isokinetic ECC strength increased significantly more in the ECC group (28.3% and 21.3%, P < 0.05). Both groups showed similar significant VO2peak improvement (ECC: 15.4% vs CON: 10.3%). The decrease in homeostasis model assessment of insulin resistance index was significant in the ECC group (−19.9%). In conclusion, although both ECC and CON cycling trainings are efficient to decrease FM, ECC induces greater FM reduction, strength gains, and insulin resistance improvements and represents an optimal modality to recommend for obese adolescents.

Child-adult differences in neuromuscular fatigue are muscle-dependent

The aim of this study was to compare the development and etiology of neuromuscular fatigue of the knee extensor (KE) and plantar flexor (PF) muscles during repeated maximal voluntary isometric contractions (MVIC) between children and adults. Twenty-one prepubertal boys (9-11 years) and 24 men (18-30 years) performed two fatigue protocols consisting in a repetition of 5-s isometric MVIC of the KE or PF muscles interspersed with 5-s passive recovery periods until MVIC reached 60% of its initial value. The etiology of neuromuscular fatigue of the KE and PF muscles was investigated by means of non-invasive methods such as the surface electromyography, single and doublet magnetic stimulation, twitch interpolation technique and NIRS. The number of repetitions performed was significantly lower in men (15.4 ± 3.8) than boys (38.7 ± 18.8) for the KE fatigue test. In contrast, no significant difference was found for the PF muscles between boys and men (12.1 ± 4.9 and 13.8 ± 4.9 repetitions, respectively). Boys displayed a lower reduction in potentiated twitch torque, low-frequency fatigue and muscle oxygenation than men whatever the muscle group considered. In contrast, voluntary activation level and normalized EMG data decreased to a greater extent in boys than men for both muscle groups. To conclude, boys experienced less peripheral and more central fatigue during repeated MVICs than men whatever the muscle group considered. However, child-adult differences in neuromuscular fatigue were muscle-dependent since boys fatigued similarly to men with the PF muscles and to a lower extent with the KE muscles than men.

Eccentric Training Improves Body Composition by Inducing Mechanical and Metabolic Adaptations: A Promising Approach for Overweight and Obese Individuals

Skeletal muscle generates force by either shortening (concentrically) or lengthening (eccentrically). Eccentric (ECC) exercise is characterized by a lower metabolic demand and requires less muscle activity than concentric (CON) exercise at the same level of exerted force. However, the specific effect of ECC training vs. CON training on lean and fat mass remains underexplored. The first aim of this paper was to review the available evidence regarding the effects of ECC training on whole body and segmental lean and fat mass and, when possible, compare these with the effects of CON training. The second aim was to provide some insights into the main mechanical, physiological, and metabolic adaptations of ECC training that contribute to its effects on body composition. The third aim was to determine the beneficial effects of ECC exercise on health-related parameters in overweight and obese patients. ECC training is an effective modality to improve lean mass, but when matched for load or work, the difference between ECC and CON trainings seems unclear. A few studies reported that ECC training is also efficient at reducing fat mass. By increasing post-exercise resting energy expenditure, modifying metabolic substrate, and improving both blood lipid profile and insulin resistance, ECC training is a potential exercise modality for individuals with chronic conditions such as those who are overweight and obese. Further investigations using standardized experimental conditions, examining not only segmental but also whole body composition, are required to compare ECC and CON trainings.

Body Composition Is Altered in Pre-Diabetic Patients With Impaired Fasting Glucose Tolerance: Results From the NHANES Survey

Background Previous studies suggest that type 2 diabetes mellitus (T2DM) is associated with a loss of muscle mass but the impact of fasting blood glucose (FBG) on body composition remains underappreciated in pre-diabetic subjects. The aim of this study was to determine the influence of FBG on lean mass (LM), fat mass (FM) and their distribution (trunk vs. appendicular), separately in middle-aged men and women. Methods One thousand nine hundred and eleven (1,911) men (63.9 ± 11.7 years) and 1,977 women (63.7 ± 12.1 years) from the National Health and Nutrition Examination Survey (1999 - 2004) were divided into four groups: normal glucose tolerance (NGT), low impaired fasting glucose (IFG), high IFG and T2DM. Body composition was obtained from dual X-ray absorptiometry (DXA). Results Of the patients, 68.7% had NGT, 16.1% low IFG, 9.4% high IFG and 5.8% T2DM. After adjustment for age, body mass index, ethnicity, smoking, alcohol and physical activity (PA), no change in appendicular LM was observed between groups, but significant increases in trunk FM (in both gender) and trunk LM (in women) were found with increased glucose intolerance (T2DM > IFG > NGT), as well as significant decreases in trunk and total LM/FM ratios (T2DM < IFG < NGT) and a significant increase in trunk/appendicular FM ratio (T2DM > IFG > NGT). Conclusions Elevated FBG within the normal range is not associated with a significant loss of appendicular LM, but modifications in LM and FM trunk and total distribution with IFG suggest that nutritional and physical lifestyle strategies should be implemented in the pre-diabetic state.

Functional Benefits of Bilateral Emphysema Reduction Surgery in an Adolescent

Acquired emphysema is a rare pathology in pediatrics. We report the case of a patient born at term with a neonatal respiratory distress, which had required mechanical ventilation. She developed gradually chronic obstructive pulmonary disease with severe emphysematous lesions, respiratory failure and functional impairments. Bilateral emphysema resection, performed at 16 years old, allowed major functional benefits at rest and during exercise. We present the results of respiratory functional evaluations, walk tests and maximal exercise tests (including measure of dynamic hyperinflation) before and after surgery, which highlights that surgery is a successful option in the treatment of compressive emphysema in childhood.