Mélanie Rance

Changes in Basal and Insulin and Amino Acid Response of Whole Body and Skeletal Muscle Proteins in Obese Men

CONTEXT Obesity-related insulin resistance of glucose and lipid metabolism may also affect protein kinetics, notably at the muscle level. OBJECTIVE We hypothesized that muscle protein response to insulin and amino acid is blunted during obesity. RESEARCH DESIGN AND METHODS Total (Tot) and mitochondrial (Mit) muscle proteins fractional synthesis rates (FSR) together with whole-body protein kinetics (WB) have been determined in postabsorptive state (PA) and during a hyperinsulinemic, hyperaminoacidemic, euglycemic clamp by using a continuous infusion of (13)C-leucine in six obese and eight nonobese subjects. RESULTS Responses of WB glucose disposal rate and protein breakdown to insulin and amino acid infusion were significantly lower in obese than in nonobese subjects (P < 0.05). In PA, Tot and Mit FSR were significantly lower (P < 0.05) in obese (Tot, 0.044 +/- 0.005% . h(-1); Mit, 0.064 +/- 0.008% . h(-1)) in comparison with nonobese subjects (Tot, 0.082 +/- 0.010% . h(-1); Mit, 0.140 +/- 0.006% . h(-1)). Tot FSR was similarly stimulated by insulin and amino acid in both groups (0.094 +/- 0.013 vs. 0.117 +/- 0.006% . h(-1), obese vs. nonobese; P < 0.05). Mit FSR was increased in nonobese subjects (0.179 +/- 0.007% . h(-1); P < 0.05) but not in obese subjects (0.078 +/- 0.012% . h(-1); P = not significant). CONCLUSIONS The obesity-related impairment of protein metabolism is characterized by 1) a reduced turnover rate of skeletal muscle proteins in PA; 2) a lack of stimulation of mitochondrial protein synthesis by insulin and amino acid; and 3) a lower inhibition of WB proteolysis by insulin and amino acid. Alterations of selective muscle protein kinetics may predispose obese subjects to muscle metabolic dysfunction leading to type 2 diabetes.

Effect of physical activity intervention on body composition in young children: influence of body mass index status and gender.

Aim: To fight overweight and obesity in childhood, this study proposes an additional physical activity (PA) in young children aged 6–10 years. The objective was to evaluate the effect of school‐based PA on the body composition according to body mass index (BMI) categories (nonobese vs. obese) and gender.

Four-Month Course of Soluble Milk Proteins Interacts With Exercise to Improve Muscle Strength and Delay Fatigue in Elderly Participants

BACKGROUND The benefit of protein supplementation on the adaptive response of muscle to exercise training in older people is controversial. OBJECTIVE To investigate the independent and combined effects of a multicomponent exercise program with and without a milk-based nutritional supplement on muscle strength and mass, lower-extremity fatigue, and metabolic markers. DESIGN A sample of 48 healthy sedentary men aged 60.8 ± 0.4 years were randomly assigned to a 16-week multicomponent exercise training program with a milk-based supplement containing, besides proteins [total milk proteins 4 or 10 g/day or soluble milk proteins rich in leucine (PRO) 10 g/day], carbohydrates and fat. Body composition, muscle mass and strength, and time to task failure, an index of muscle fatigue, were measured. Blood lipid, fibrinogen, creatine phosphokinase, glucose, insulin, C-reactive protein, interleukin-6, tumor necrosis factor-α soluble receptors, and endothelial markers were assessed. RESULTS Body fat mass was reduced after the 4-month training program in groups receiving 10 g/day of protein supplementation (P < .01). The training program sustained with the daily 10 g/day PRO was associated with a significant increase in dominant fat free mass (+5.4%, P < .01) and in appendicular muscle mass (+4.5%, P < .01). Blood cholesterol was decreased in the trained group receiving 10 g/day PRO. The index of insulin resistance (homeostasis model assessment-insulin resistance) and blood creatine phosphokinase were reduced in the groups receiving 10 g/day PRO, irrespective of exercise. The inflammatory and endothelial markers were not different between the groups. Training caused a significant improvement (+10.6% to 19.4%, P < .01) in the maximal oxygen uptake. Increased maximum voluntary contraction force was seen in the trained groups receiving 10 g/day of proteins (about 3%, P < .05). Time to task failure was improved in the trained participants receiving a 10 g/day supplementation with PRO (P < .01). CONCLUSIONS Soluble milk proteins rich in leucine improved time to muscle failure and increase in skeletal muscle mass and strength after prolonged multicomponent exercise training in healthy older men.

Lower-limb and whole-body tissue composition assessment in healthy active older women

Aim: The study evaluated, in active elderly women, the accuracy and bias of anthropometry and bioelectrical impedance analysis (BIA) for lower-limb and whole-body tissue composition measures using dual-energy X-ray absorptiometry (DXA) as the criterion method. Methods: Nineteen individuals (66.1 ± 4.2 years) participated in the study. Whole-body fat mass (FM) and fat-free mass (FFM) were measured by anthropometry, BIA and DXA. Lower-limb volume (LLV) and lower-limb FFM (LLFFM) were assessed by anthropometry and DXA. Results: LLV and LLFFM were significantly overestimated by anthropometry vs. DXA (p<0.05 and p<0.001, respectively) but significant relationships were observed [coefficient of determination (R2)>0.25, p<0.05]. No significant difference was observed between FMA (where A stands for anthropometry) vs. FMDXA and FFMA vs. FFMDXA and significant relationships were observed [R2 = 0.93, p<0.001, coefficient of variation (CV) = 7.3%; and R2 = 0.85, p<0.001, CV = 4.4%, respectively]. No significant difference was observed between FMBIA and FMDXA and a significant relationship was observed (R2 = 0.80, p<0.001, CV = 11.6%). FFM was significantly underestimated by BIA vs. DXA (p<0.01). Conclusions: In active elderly women, (i) compared with DXA, anthropometry overestimates LLV and LLFFM; (ii) anthropometry can be an accurate method for assessing whole-body composition; and (iii) despite a non-significant bias for the FM measurement, the BIA tends to overestimate FM and underestimate FFM. Résumé. But: Cette étude évalue la précision et l’écart entre anthropométrie et analyse d’impédance bioélectrique (AIB) pour le membre inférieur et les mesures de composition des tissus pour l’ensemble du corps par la méthode d’absorptiométrie d’énergie double de rayons X (ADX) chez des femmes âgées actives. Méthodes: Dix neuf individus (66,1 ± 4,2 ans) ont participé à l’étude. La masse grasse totale (MG) et la masse maigre (MM) ont été mesurées par anthropométrie, AIB et ADX. Le volume du membre inférieur (VMI) et la masse maigre du membre inférieur (MMMI) l’ont été par anthropométrie et ADX. Résultats: Le VMI et la MMMI sont significativement surestimés par l’anthropométrie en comparaison avec l’ADX (respectivement p<0,05 et p<0,001) mais des corrélations significatives existent entre les deux mesures [coefficient de détermination R2>0,25 p<0,05]. On n’observe pas de différence significative entre MGA (A = anthropométrie) par rapport à la MGADX et entre MMA par rapport à MMADX et on observe des corrélations significatives [respectivement R2 = 0,93 p<0,001 coefficient de variation CV = 7,3% et R2 = 0,85 p<0,001, CV = 4,4%]. On n’observe pas de différence significative entre MGAIB et MGADX et une corrélation significative existe entre les deux mesures [R2 = 0,80, p<0,001, CV = 11, 6%]. La MM est significativement sous estimée par l’AIB par rapport à l’ADX. Conclusion: Chez les femmes âgées actives, (i) l’anthropométrie surestime le VMI et la MMMI par rapport à l’ADX ; (ii) l’anthropométrie peut être une méthode précise de la mesure de la composition corporelle et (iii) en dépit d’un écart non significatif pour les mesures de la MG, l’AIB tend à surestimer la MG et sous estimer la MM. Zusammenfassung. Ziel: Die Studie untersuchte bei aktiven älteren Frauen die Genauigkeit und den Messfehler anthropometrischer und bioelektrischer Impedanzanalysen (BIA) von Messungen der Unterschenkel- und Ganzkörperzusammensetzung, wobei die Dual-energy Röntgenabsorptionsspektrometrie (dual-energy X-ray absorptiometry, DEXA) als Referenzmethode herangezogen wurde. Methoden: 19 Personen (66,1 ± 4,2 Jahre) nahmen an der Untersuchung teil. Ganzkörperfettmasse (FM) und fettfreie Masse (FFM) wurden mittels Anthropometrie, BIA und DEXA bestimmt. Unterschenkelvolumen (lower-limb volume, LLV) und Unterschenkel FFM (LLFFM) wurden mittels Anthropometrie und DEXA bestimmt. Ergebnisse: LLV und LLFFM wurden bei Verwendung der Anthropometrie im Vergleich zu DEXA signifikant überschätzt (p<0,05, bzw. p<0,001), aber es wurden untereinander signifikante Beziehungen beobachtet [coefficient of determination (R2)>0,25, p<0.05]. Keine signifikanten Unterschiede wurden zwischen FMA (wobei A für Anthropometrie steht) gegenüber FMDXA und FFMA gegenüber FFMDXA beobachtet [R2 = 0,93, p<0,001, Variationskoeffizient (CV) = 7,3%, bzw. R2 = 0,85, p<0,001, CV = 4,4%]. Es wurden keine signifikanten Unterschiede zwischen FMBIA und FMDXA beobachtet, aber eine signifikante Beziehung (R2 = 0,80, p<0,001, CV = 11,6%). FFM wurde bei Verwendung von BIA signifikant gegenüber DEXA unterschätzt (p<0,01). Zusammenfassung: (i) bei aktiven älteren Frauen unterschätzt die Anthropometrie das LLV und das LLFFM verglichen mit DEXA, (ii) Anthropometrie kann eine sichere Methode für die Bestimmung der Ganzkörperzusammensetzung sein; und (iii) trotz eines nicht-signifikanten Messfehlers für FM tendiert BIA dazu, FM zu überschätzen und FFM zu unterschätzen. Resumen. Objetivo: El estudio evaluaba, en mujeres ancianas activas, la precisión y el sesgo de la antropometría y del análisis de impedancia bioeléctrica (BIA) para medir la composición corporal de la extremidad inferior y del tejido corporal total, utilizando absorciometría de rayos X de doble energía (DXA) como método de referencia. Métodos: En el estudio participaron 19 individuos (66,1 ± 4,2 años). Se midieron por antropometría, BIA y DXA la masa grasa corporal total (FM) y la masa libre de grasa (FFM). El volumen de la extremidad inferior (LLV) y la FFM de la extremidad inferior (LLFFM) se estimaron mediante antropometría y DXA. Resultados: El LLV y la LLFFM se sobrestimaron significativamente mediante antropometría vs. DXA (p<0,05 y p<0,0001, respectivamente), pero se observaron relaciones significativas [coeficiente de determinación (R2)>0,25, p<0,05]. No se observaron diferencias significativas entre FMA (donde A representa a la antropometría) vs. FMDXA y FFM A vs. FFMDXA y se observó una relación significativa [R2 = 0,93, p<0,001, coeficiente de variación (CV) = 7,3%; y R2 = 0,85, p<0,001, CV = 4,4%, respectivamente]. No se han observado diferencias significativas entre FMBIA y FMDXA y se encontró una relación significativa (R2 = 0,80, p<0,001, CV = 11,6%). La FFM se subestimó significativamente mediante BIA vs. DXA (p<0,01). Conclusiones: En mujeres ancianas activas, (i) la antropometría sobreestima el LLV y la LLFFM comparada con el uso de DXA, (ii) la antropometría puede ser un método preciso para estimar la composición corporal total, y (iii) a pesar de un sesgo no significativo en la medida de FM, el BIA tiende a sobrestimar la FM y a subestimar la FFM.