RESUMEN
Background: In older persons, muscle loss is accelerated during physical inactivity and hypoenergetic states, both of which are features of hospitalization. Protein supplementation may represent a strategy to offset the loss of muscle during inactivity, and enhance recovery on resumption of activity. Objective: We aimed to determine if protein supplementation, with proteins of substantially different quality, would alleviate the loss of lean mass by augmenting muscle protein synthesis (MPS) while inactive during a hypoenergetic state. Design: Participants (16 men, mean ± SD age: 69 ± 3 y; 15 women, mean ± SD age: 68 ± 4 y) consumed a diet containing 1.6 g protein · kg-1 · d-1, with 55% ± 9% of protein from foods and 45% ± 9% from supplements, namely, whey protein (WP) or collagen peptides (CP): 30 g each, consumed 2 times/d. Participants were in energy balance (EB) for 1 wk, then began a period of energy restriction (ER; -500 kcal/d) for 1 wk, followed by ER with step reduction (ER + SR; <750 steps/d) for 2 wk, before a return to habitual activity in recovery (RC) for 1 wk. Results: There were significant reductions in leg lean mass (LLM) from EB to ER, and from ER to ER + SR in both groups (P < 0.001) with no differences between WP and CP or when comparing the change from phase to phase. During RC, LLM increased from ER + SR, but in the WP group only. Rates of integrated muscle protein synthesis decreased during ER and ER + SR in both groups (P < 0.01), but increased during RC only in the WP group (P = 0.05). Conclusions: Protein supplementation did not confer a benefit in protecting LLM, but only supplemental WP augmented LLM and muscle protein synthesis during recovery from inactivity and a hypoenergetic state. This trial was registered at http://www.clinicaltrials.gov as NCT03285737.
Asunto(s)
Suplementos Dietéticos , Ingestión de Energía , Actividad Motora , Proteínas Musculares/biosíntesis , Músculo Esquelético/efectos de los fármacos , Biosíntesis de Proteínas/efectos de los fármacos , Proteína de Suero de Leche/farmacología , Anciano , Restricción Calórica , Colágeno/farmacología , Convalecencia , Metabolismo Energético , Femenino , Hospitalización , Humanos , Pierna , Masculino , Músculo Esquelético/metabolismo , Péptidos/farmacología , Descanso , CaminataRESUMEN
Background: Nutritional supplementation can have beneficial effects on body composition, strength, and function in older adults. However, whether the response of satellite cells can be altered by nutritional supplementation in older adults remains unknown. Objective: We assessed whether a multi-ingredient protein-based supplement taken over a prolonged period of time could alter the muscle satellite cell response after exercise in older men. Methods: Twenty-seven older men [mean ± SD age: 73 ± 1 y; mean ± SD body mass index (kg/m2): 28 ± 1] participated in a randomized double-blind experiment. Participants were randomly divided into an experimental (EXP) group (n = 13) who consumed a multi-ingredient protein-based supplement [30 g whey protein, 2.5 g creatine, 500 IU vitamin D, 400 mg Ca, and 1500 mg n-3 (ω-3) polyunsaturated fatty acids] 2 times/d for 7 wk or a control (CON; 22 g maltodextrin) group (n = 14). After 7 wk of supplementation, all participants performed a single resistance exercise session, and muscle biopsy samples were taken from the vastus lateralis before and 24 and 48 h after exercise. Immunohistochemistry was used to assess the change in type I and II muscle fiber satellite cell content and activation status of the cells. In addition, mRNA expression of the myogenic regulatory factors was determined by using reverse transcriptase-polymerase chain reaction. Results: In response to the single bout of exercise, type I muscle fiber satellite cell content was significantly increased at 24 h (0.132 ± 0.015 and 0.131 ± 0.011 satellite cells/fiber in CON and EXP groups, respectively) and 48 h (0.126 ± 0.010 and 0.120 ± 0.012 satellite cells/fiber in CON and EXP groups, respectively) compared with pre-exercise (0.092 ± 0.007 and 0.118 ± 0.017 satellite cells/fiber in CON and EXP groups, respectively) muscle biopsy samples (P < 0.01), with no difference between the 2 groups. In both groups, we observed no significant changes in type II muscle fiber satellite cell content after exercise. Conclusion: Ingesting a multi-ingredient protein-based supplement for 7 wk did not alter the type I or II muscle fiber satellite cell response during postexercise recovery in older men. This trial was registered at www.clinicaltrials.gov as NCT02281331.
Asunto(s)
Suplementos Dietéticos , Ejercicio Físico/fisiología , Células Satélite del Músculo Esquelético/efectos de los fármacos , Células Satélite del Músculo Esquelético/fisiología , Anciano , Calcio/administración & dosificación , Calcio/farmacología , Creatina/administración & dosificación , Creatina/farmacología , Método Doble Ciego , Combinación de Medicamentos , Ácidos Grasos Insaturados/administración & dosificación , Ácidos Grasos Insaturados/farmacología , Regulación de la Expresión Génica/efectos de los fármacos , Humanos , Masculino , ARN Mensajero/genética , ARN Mensajero/metabolismo , Vitamina D/administración & dosificación , Vitamina D/farmacología , Proteína de Suero de Leche/administración & dosificaciónRESUMEN
BACKGROUND: Leucine co-ingestion with lower-protein (LP)-containing meals may overcome the blunted muscle protein synthetic response to food intake in the elderly but may be effective only in individuals who consume LP diets. OBJECTIVE: We examined the impact of leucine co-ingestion with mixed macronutrient meals on integrated 3-d rates of myofibrillar protein synthesis (MyoPS) in free-living older men who consumed higher protein (HP) (1.2 g · kg-1 · d-1) or LP (0.8 g · kg-1 · d-1) in rested and resistance exercise (REX) conditions. DESIGN: In a crossover design, 20 healthy older men [aged 65-85 y] were randomly assigned to receive LP or HP diets while ingesting a placebo (days 0-2) and Leu supplement (5 g leucine/meal; days 3-5) with their 3 main daily meals. A bout of unilateral REX was performed during the placebo and Leu treatments. Ingested 2H2O and skeletal muscle biopsies were used to measure the 3-d integrated rate of MyoPS during the placebo and Leu treatments in the rested and REX legs. RESULTS: Leucinemia was higher with Leu treatment than with placebo treatment (P < 0.001). MyoPS was similar in LP and HP during both treatments (P = 0.39) but was higher with Leu treatment than with placebo treatment in the rested (pooled mean ± SD: Leu, 1.57% ± 0.11%/d; placebo, 1.48% ± 0.08%/d; main effect of treatment: P < 0.001) and REX (pooled mean: Leu, 1.87% ± 0.09%/d; placebo, 1.71 ± 0.10%/d; main effect of treatment: P < 0.001) legs. CONCLUSIONS: Leu co-ingestion with daily meals enhances integrated MyoPS in free-living older men in rested and REX conditions and is equally effective in older men who consume daily protein intakes greater than or equal to the RDA. This trial was registered at clinicaltrials.gov as NCT02371278.