Effects of a multidisciplinary body weight reduction program on static and dynamic thoraco-abdominal volumes in obese adolescents

Abstract

Abstract:The objective of this study was to characterize static and dynamic thoraco-abdominal volumes in obese adolescents and to test the effects of a 3-week multidisciplinary body weight reduction program (MBWRP), entailing an energy-restricted diet, psychological and nutritional counseling, aerobic physical activity, and respiratory muscle endurance training (RMET), on these parameters. Total chest wall (V CW ), pulmonary rib cage (V RC,p ), abdominal rib cage (V RC,a ), and abdominal (V AB ) volumes were measured on 11 male adolescents (Tanner stage: 3-5; BMI standard deviation score: >2; age: 15.9 ± 1.3 years; percent body fat: 38.4%) during rest, inspiratory capacity (IC) maneuver, and incremental exercise on a cycle ergometer at baseline and after 3 weeks of MBWRP. At baseline, the progressive increase in tidal volume was achieved by an increase in end-inspiratory V CW (p < 0.05) due to increases in V RC,p and V RC,a with constant V AB . End-expiratory V CW decreased with late increasing V RC,p , dynamically hyperinflating V RC,a (p < 0.05), and progressively decreasing V AB (p < 0.05). After MBWRP, weight loss was concentrated in the abdomen and total IC decreased. During exercise, abdominal rib cage hyperinflation was delayed and associated with 15% increased performance and reduced dyspnea at high workloads (p < 0.05) without ventilatory and metabolic changes. We conclude that otherwise healthy obese adolescents adopt a thoracoabdominal operational pattern characterized by abdominal rib cage hyperinflation as a form of lung recruitment during incremental cycle exercise. Additionally, a short period of MBWRP including RMET is associated with improved exercise performance, lung and chest wall volume recruitment, unloading of respiratory muscles, and reduced dyspnea.Key words: obesity, pediatrics, exercise, pulmonary physiology, exercise physiology, kinesiology.Résumé : Cette étude a pour objectif de déterminer les volumes thoraco-abdominaux statiques et dynamiques chez des adolescents obèses et d'évaluer sur ces variables les effets de 3 semaines d'un programme multidisciplinaire de perte de poids (MBWRP) comprenant un régime restrictif, du counseling psychologique et nutritionnel, de l'activité physique aérobie et un entraînement en endurance des muscles respiratoires (RMET). On mesure les volumes de la cage thoracique totale (V CW ), du compartiment pulmonaire (V RC,p ), du compartiment abdominal (V RC,a ) et de l'abdomen (V AB ) de 11 adolescents mâles (stade de Tanner : 3-5, IMC > 2 écarts-types, âge 15,9 ± 1,3 ans, pourcentage de gras corporel : 38,4 %) au repos, la capacité inspiratoire (IC), une manoeuvre de capacité inspiratoire (IC) et un test d'effort progressif sur cycloergomètre au début et après 3 semaines de MBWRP. Au début, le volume courant s'accroit progressivement par l'augmentation de V CW à la fin de l'inspiration (p < 0,05) due à l'agrandissement des deux compartiments de la cage thoracique, V AB demeurant constant. V CW à la fin de l'expiration diminue en présence d'une augmentation...

Three weeks of respiratory muscle endurance training improve the O2 cost of walking and exercise tolerance in obese adolescents

“…Reduced RPE following RMET was described also by LoMauro et al. (). Further linking the reduced O 2 cost of walking to an enhanced exercise tolerance, in the present study the effects of RMET on O 2 (Fig.…”

“…A limitation of the present study is represented by the fact that no direct measurements of the work of breathing and of the O 2 cost of breathing were performed. In a previous study carried out by our group in obese adolescents during cycling, however, we observed by optoelectronic plethysmography significant changes of static and dynamic thoraco-abdominal volumes of breathing following a RMET protocol identical to that of the present study (LoMauro et al 2016). More specifically, the patients showed abdominal rib cage hyperinflation as a form of lung recruitment during exercise, with a move to higher operating volumes.…”

“…A previous study by our group (LoMauro et al. ) on a similar population described that 3 weeks of RMET is enough to reduce abdominal load, recruit lung and chest wall volumes, and as a result increase FVC. No differences between groups at baseline were observed for spirometry variables.…”

“…) and in the present one, in which several physiological variables related to exercise tolerance were directly determined, allowing mechanistic insights into the factors potentially responsible for the observed changes, such as the effects of RMET on respiratory mechanics (LoMauro et al. ), the reduced O 2 cost of exercise, the “metaboreflex” concept discussed above. The same concepts apply to another study (Edwards et al.…”

“…Three weeks of RMET were enough to reduce the abdominal load, recruit lung and chest wall volumes, unload RM and delay the abdominal rib cage hyperinflation (LoMauro et al. ). These effects, which were not determined in the present study, resulted in a reduced dyspnea and an enhanced exercise tolerance, and would be presumably associated with reduced work of breathing and O 2 cost of breathing.…”