Showing papers by "Elena Volpi published in 2015"
TL;DR: In this article, the authors found that older adults are more susceptible than young persons to muscle loss after short-term bed rest, which may be partially explained by a combined suppression of protein synthesis and a marginal increase in proteolytic markers.
Abstract: Bed rest-induced muscle loss and impaired muscle recovery may contribute to age-related sarcopenia. It is unknown if there are age-related differences in muscle mass and muscle anabolic and catabolic responses to bed rest. A secondary objective was to determine if rehabilitation could reverse bed rest responses. Nine older and fourteen young adults participated in a 5-day bed rest challenge (BED REST). This was followed by 8 weeks of high intensity resistance exercise (REHAB). Leg lean mass (via dual-energy X-ray absorptiometry; DXA) and strength were determined. Muscle biopsies were collected during a constant stable isotope infusion in the postabsorptive state and after essential amino acid (EAA) ingestion on three occasions: before (PRE), after bed rest and after rehabilitation. Samples were assessed for protein synthesis, mTORC1 signalling, REDD1/2 expression and molecular markers related to muscle proteolysis (MURF1, MAFBX, AMPKα, LC3II/I, Beclin1). We found that leg lean mass and strength decreased in older but not younger adults after bedrest (P < 0.05) and was restored after rehabilitation. EAA-induced mTORC1 signalling and protein synthesis increased before bed rest in both age groups (P < 0.05). Although both groups had blunted mTORC1 signalling, increased REDD2 and MURF1 mRNA after bedrest, only older adults had reduced EAA-induced protein synthesis rates and increased MAFBX mRNA, p-AMPKα and the LC3II/I ratio (P < 0.05). We conclude that older adults are more susceptible than young persons to muscle loss after short-term bed rest. This may be partially explained by a combined suppression of protein synthesis and a marginal increase in proteolytic markers. Finally, rehabilitation restored bed rest-induced deficits in lean mass and strength in older adults.
147 citations
TL;DR: There remains a need for large, long-term, randomized clinical trials examining whether the positive effects of dietary protein on muscle metabolism seen in acute studies will translate over the long term into gains of muscle mass, function, and the overall health of older adults.
Abstract: Purpose of reviewWe provide an update on the recent advances in nutrition research regarding the role of protein intake in the development and treatment of sarcopenia of aging.Recent findingsSpecific muscle mass, strength and function cut-points for the diagnosis of sarcopenia have been identified.
146 citations
TL;DR: It is concluded that age and sex do not influence basal muscle protein synthesis, however, basal mTORC1 hyperphosphorylation in the elderly may contribute to insulin resistance and the age-related anabolic resistance of skeletal muscle protein metabolism to nutrition and exercise.
114 citations
TL;DR: It is concluded that skeletal muscle mitochondrial respiratory capacity and coupling control decline with age, which result in a reduced capacity for ATP production in skeletal muscle of older adults.
Abstract: Mitochondrial health is critical to physiological function, particularly in tissues with high ATP turnover, such as striated muscle. It has been postulated that derangements in skeletal muscle mitochondrial function contribute to impaired physical function in older adults. Here, we determined mitochondrial respiratory capacity and coupling control in skeletal muscle biopsies obtained from young and older adults. Twenty-four young (28 ± 7 yr) and thirty-one older (62 ± 8 yr) adults were studied. Mitochondrial respiration was determined in permeabilized myofibers from the vastus lateralis after the addition of substrates oligomycin and CCCP. Thereafter, mitochondrial coupling control was calculated. Maximal coupled respiration (respiration linked to ATP production) was lower in muscle from older vs. young subjects (P < 0.01), as was maximal uncoupled respiration (P = 0.06). Coupling control in response to the ATP synthase inhibitor oligomycin was lower in older adults (P < 0.05), as was the mitochondria flux control ratio, coupled respiration normalized to maximal uncoupled respiration (P < 0.05). Calculation of respiratory function revealed lower respiration linked to ATP production (P < 0.001) and greater reserve respiration (P < 0.01); i.e., respiratory capacity not used for phosphorylation in muscle from older adults. We conclude that skeletal muscle mitochondrial respiratory capacity and coupling control decline with age. Lower respiratory capacity and coupling efficiency result in a reduced capacity for ATP production in skeletal muscle of older adults.
101 citations
TL;DR: A mechanism involving more efficient elimination of excess acyl groups derived from BCAA and aromatic AA metabolism via glycine conjugation in the liver, rather than increased BCAA disposal through oxidation and turnover, may mediate interactions between exercise, BCAA metabolism and IS.
Abstract: Aims/hypotheses
Obesity is associated with decreased insulin sensitivity (IS) and elevated plasma branched-chain amino acids (BCAAs). The purpose of this study was to investigate the relationship between BCAA metabolism and IS in overweight (OW) individuals during exercise intervention.
99 citations
06 Mar 2015
3 citations
TL;DR: The use of the Short Physical Performance Battery (SPPB) and step count monitoring for the first time to demonstrate physical improvements in a patient with lumbar stenosis.
2 citations
TL;DR: Soy-dairy protein blend ingestion prolongs the muscle protein synthesis response to a bout of resistance exercise, and the efficacy of PB supplementation with resistance exercise training withRET is confirmed.
Abstract: Soy-dairy protein blend (PB) ingestion prolongs the muscle protein synthesis response to a bout of resistance exercise. The efficacy of PB supplementation with resistance exercise training (RET) ha...
2 citations
TL;DR: This debate is ongoing as how to best define and measure sarcopenia, and several operative definitions have been published by international consensus panels over the past few years.
Abstract: Debate is ongoing as how to best define and measure sarcopenia. Several operative definitions have been published by international consensus panels over the past few years. In the absence of standa...
1 citations