Showing papers by "Elena Volpi published in 2016"

Efficacy and safety of leucine supplementation in the elderly

Abstract: Leucine supplementation has grown in popularity due to the discovery of its anabolic effects on cell signaling and protein synthesis in muscle. The current recommendation is a minimum intake of 55 mg ⋅ kg-1. d-1 Leucine acutely stimulates skeletal muscle anabolism and can overcome the anabolic resistance of aging. The value of chronic leucine ingestion for muscle growth is still unclear. Most of the research into leucine consumption has focused on efficacy. To our knowledge, very few studies have sought to determine the maximum safe level of intake. Limited evidence suggests that intakes of ≤1250 mg ⋅ kg-1. d-1 do not appear to have any health consequences other than short-term elevated plasma ammonia concentrations. Similarly, no adverse events have been reported for the leucine metabolite β-hydroxy-β-methylbutyrate (HMB), although no studies have tested HMB toxicity in humans. Therefore, future research is needed to evaluate leucine and HMB toxicity in the elderly and in specific health conditions.

Soy-Dairy Protein Blend or Whey Protein Isolate Ingestion Induces Similar Postexercise Muscle Mechanistic Target of Rapamycin Complex 1 Signaling and Protein Synthesis Responses in Older Men

Abstract: BACKGROUND Previous work demonstrated that a soy-dairy protein blend (PB) prolongs hyperaminoacidemia and muscle protein synthesis in young adults after resistance exercise OBJECTIVE We investigated the effect of PB in older adults We hypothesized that PB would prolong hyperaminoacidemia, enhancing mechanistic target of rapamycin complex 1 (mTORC1) signaling and muscle protein anabolism compared with a whey protein isolate (WPI) METHODS This double-blind, randomized controlled trial studied men 55-75 y of age Subjects consumed 30 g protein from WPI or PB (25% soy, 25% whey, and 50% casein) 1 h after leg extension exercise (8 sets of 10 repetitions at 70% one-repetition maximum) Blood and muscle amino acid concentrations and basal and postexercise muscle protein turnover were measured by using stable isotopic methods Muscle mTORC1 signaling was assessed by immunoblotting RESULTS Both groups increased amino acid concentrations (P < 005) and mTORC1 signaling after protein ingestion (P < 005) Postexercise fractional synthesis rate (FSR; P ≥ 005), fractional breakdown rate (FBR; P ≥ 005), and net balance (P = 008) did not differ between groups WPI increased FSR by 67% (mean ± SEM: rest: 005% ± 001%; postexercise: 009% ± 001%; P < 005), decreased FBR by 46% (rest: 017% ± 001%; postexercise: 009% ± 003%; P < 005), and made net balance less negative (P < 005) PB ingestion did not increase FSR (rest: 007% ± 003%; postexercise: 009% ± 001%; P ≥ 005), tended to decrease FBR by 42% (rest: 025% ± 008%; postexercise: 015% ± 008%; P = 008), and made net balance less negative (P < 005) Within-group percentage of change differences were not different between groups for FSR, FBR, or net balance (P ≥ 005) CONCLUSIONS WPI and PB ingestion after exercise in older men induced similar responses in hyperaminoacidemia, mTORC1 signaling, muscle protein synthesis, and breakdown These data add new evidence for the use of whey or soy-dairy PBs as targeted nutritional interventions to counteract sarcopenia This trial was registered at clinicaltrialsgov as NCT01847261

Brown adipose tissue is linked to a distinct thermoregulatory response to mild cold in people

Abstract: Brown adipose tissue (BAT) plays an important role in thermoregulation in rodents. Its role in temperature homeostasis in people is less studied. To this end, we recruited 18 men [8 subjects with no/minimal BAT activity (BAT-) and 10 with pronounced BAT activity (BAT+)]. Each volunteer participated in a 6 h, individualized, non-shivering cold exposure protocol. BAT was quantified using positron emission tomography/computed tomography. Body core and skin temperatures were measured using a telemetric pill and wireless thermistors, respectively. Core body temperature decreased during cold exposure in the BAT- group only (-0.34°C, 95% CI: -0.6 to -0.1, p = 0.03), while the cold-induced change in core temperature was significantly different between BAT+ and BAT- subjects (BAT+ vs. BAT-, 0.43°C, 95% CI: 0.20-0.65, p = 0.0014). BAT volume was associated with the cold-induced change in core temperature (p = 0.01) even after adjustment for age and adiposity. Compared to the BAT- group, BAT+ subjects tolerated a lower ambient temperature (BAT-: 20.6 ± 0.3°C vs. BAT+: 19.8 ± 0.3°C, p = 0.035) without shivering. The cold-induced change in core temperature (r = 0.79, p = 0.001) and supraclavicular temperature (r = 0.58, p = 0.014) correlated with BAT volume, suggesting that these non-invasive measures can be potentially used as surrogate markers of BAT when other methods to detect BAT are not available or their use is not warranted. These results demonstrate a physiologically significant role for BAT in thermoregulation in people. This trial has been registered with Clinaltrials.gov: NCT01791114 (https://clinicaltrials.gov/ct2/show/NCT01791114).

Testing the effects of narrative and play on physical activity among breast cancer survivors using mobile apps: study protocol for a randomized controlled trial

Abstract: Physical activity reduces risk for numerous negative health outcomes, but postmenopausal breast cancer survivors do not reach recommended levels. Many interventions encourage self-monitoring of steps, which can increase physical activity in the short term. However, these interventions appear insufficient to increase motivation for sustained change. There is a need for innovative strategies to increase physical activity motivation in this population. Narratives are uniquely persuasive, and video games show promise for increasing motivation. This study will determine the effectiveness of an intervention that combines narrative and gaming to encourage sustained physical activity.

Protein Supplementation Has Minimal Effects on Muscle Adaptations during Resistance Exercise Training in Young Men: A Double-Blind Randomized Clinical Trial

Abstract: Background: To our knowledge the efficacy of soy-dairy protein blend (PB) supplementation with resistance exercise training (RET) has not been evaluated in a longitudinal study. Objective: Our aim was to determine the effect of PB supplementation during RET on muscle adaptation. Methods: In this double-blind randomized clinical trial, healthy young men [18–30 y; BMI (in kg/m2): 25 ± 0.5] participated in supervised whole-body RET at 60–80% 1-repetition maximum (1-RM) for 3 d/wk for 12 wk with random assignment to daily receive 22 g PB (n = 23), whey protein (WP) isolate (n = 22), or an isocaloric maltodextrin (carbohydrate) placebo [(MDP) n = 23]. Serum testosterone, muscle strength, thigh muscle thickness (MT), myofiber cross-sectional area (mCSA), and lean body mass (LBM) were assessed before and after 6 and 12 wk of RET. Results: All treatments increased LBM (P 0.10) between treatments. Testosterone was not altered. Conclusions: PB supplementation during 3 mo of RET tended to slightly enhance gains in whole-body and arm LBM, but not leg muscle mass, compared with RET without protein supplementation. Although protein supplementation minimally enhanced gains in LBM of healthy young men, there was no enhancement of gains in strength. This trial was registered at clinicaltrials.gov as {"type":"clinical-trial","attrs":{"text":"NCT01749189","term_id":"NCT01749189"}}NCT01749189.

Short-Term Intensive Rehabilitation Induces Recovery of Physical Function After 7 Days of Bed Rest in Older Adults

Abstract: Purpose:Hospitalization can result in functional loss, especially in older adults. The purpose of the study was to determine the effect of intensive rehabilitation on changes in physical function in healthy older subjects after 1 week of bed rest and 3 days of rehabilitation. Methods:Six healthy subjects older than 60 years completed 7 days of bed rest followed by 3 days of rehabilitation including stretching, strengthening, balance, gait, and stair climbing. Results:Bed rest reduced the distance walked over 6 minutes, slowed gait speeds, and increased sit-to-stand times. Muscle flexibility and isokinetic quadriceps strength varied after bed rest. Three days of rehabilitation restored outcomes measures to baseline levels. Conclusions:A short bout of focused rehabilitation after a week of bed rest restored physical function measures to pre-bed rest levels in healthy older subjects. Similar training protocols may result in increased functional measures in older hospitalized patients.

Comparison of Five Malnutrition Screening Tools in a Cohort of Acutely Ill Older Adults

Abstract: Over the last decades numerous nutrition screening tools have been developed. Currently there is no international consensus on a single ‘best tool’ to determine the prevalence of malnutrition in ac...