Effects of GLP-1 Infusion Upon Whole-body Glucose Uptake and Skeletal Muscle Perfusion During Fed-state in Older Men.

INTRODUCTION: Ageing skeletal muscles become both insulin resistant and atrophic. The hormone glucagon-like peptide 1 (GLP-1) facilitates postprandial glucose uptake as well as augmenting muscle perfusion, independent of insulin action. We thus hypothesized exogenous GLP-1 infusions would enhance muscle perfusion and positively affect glucose metabolism during fed-state clamps in older people. METHODS: Eight men (71 ± 1 years) were studied in a randomized crossover trial. Basal blood samples were taken before postprandial (fed-state) insulin and glucose clamps, accompanied by amino acid infusions, for 3 hours. Reflecting this, following insertions of peripheral and femoral vessels cannulae and baseline measurements, peripheral IV infusions of octreotide, insulin (Actrapid), 20% glucose, and mixed amino acids; Vamin 14-EF with or without a femoral arterial GLP-1 infusion were started. GLP-1, insulin, and C-peptide were measured by ELISA. Muscle microvascular blood flow was assessed via contrast enhanced ultrasound. Whole-body glucose handling was assayed by assessing glucose infusion rate parameters. RESULTS: Skeletal muscle microvascular blood flow significantly increased in response to GLP-1 vs feeding alone (5.0 ± 2.1 vs 1.9 ± 0.7 fold-change from basal, respectively; P = 0.008), while also increasing whole-body glucose uptake (area under the curve 16.9 ± 1.7 vs 11.4 ± 1.8 mg/kg-1/180 minutes-1, P = 0.02 ± GLP, respectively). CONCLUSIONS: The beneficial effects of GLP-1 on whole-body glycemic control are evident with insulin clamped at fed-state levels. GLP-1 further enhances the effects of insulin on whole-body glucose uptake in older men, underlining its role as a therapeutic target. The effects of GLP-1 in enhancing microvascular flow likely also affects other glucose-regulatory organs, reflected by greater whole-body glucose uptake.

Long-Term Effect of Exercise on Irisin Blood Levels-Systematic Review and Meta-Analysis.

Physical exercise may activate a number of important biochemical processes in the human body. The aim of this systematic review and meta-analysis was to identify the long-term effect of physical activity on irisin blood levels. We searched PubMed, Scopus, and Web of Science for articles addressing the long-term effect of physical exercise on irisin blood levels. Fifty-nine articles were included in the final qualitative and quantitative syntheses. A statistically significant within-group effect of exercise on irisin blood levels was in 33 studies; out of them, the irisin level increased 23× and decreased 10×. The significant positive between-groups effect was found 11×. Furthermore, the meta-analysis indicated that physical exercise had a significant positive effect on irisin blood levels (SMD = 0.39 (95% CI 0.27-0.52)). Nevertheless, considerably high heterogeneity was found in all the analyses. This systematic review and meta-analysis indicate that physical exercise might increase irisin blood levels; however, the results of individual studies were considerably inconsistent, which questions the methodological detection of irisin by ELISA kits.

The Effects of High Mineral Alkaline Water Consumed Over Three Consecutive Days on Reaction Time Following Anaerobic Exercise - A Randomized Placebo-Controlled Crossover Pilot Study.

Drinking alkaline water after intense anaerobic exercise may enhance both cognitive and physical performance. This study aimed to investigate the effect of high mineral alkaline water consumed over three consecutive days on reaction time after anaerobic exercise in twelve healthy young males (aged 21.1 ± 1.3 years) with a valid sports medical examination. Participants were excluded when they took any medications or performance-enhancing supplements for the period of at least four weeks before the study commenced. Participants were randomly divided into two groups in this double-blind, placebo-controlled crossover pilot study. They ingested either alkaline water (AW) or regular table water ( RTW) for three consecutive days before anaerobic exercise. The anaerobic exercise consisted of two 2-min high-intensity step-tests with a passive rest interval of 3 minutes between the two bouts of exercise. Performance in the step-test (W), reaction time for visual and auditory signals, the rate of perceived exertion (RPE), urine specific gravity, and lactate concentration were analysed. No effect of AW was found on reaction time and the other variables except anaerobic performance. An-aerobic performance was significantly higher after ingestion of AW in both step-tests (p < 0.05). The ingestion of AW for three consecutive days before anaerobic exercise seems to positively affect anaerobic performance.

Feeding Your Himalayan Expedition: Nutritional Signatures and Body Composition Adaptations of Trekkers and Porters.

High-altitude exposure leads to many physiological challenges, such as weight loss and dehydration. However, little attention has been posed to the role of nutrition and ethnic differences. Aiming to fulfill this gap, five Italian trekkers and seven Nepalese porters, all males, recorded their diet in diaries during a Himalayan expedition (19 days), and the average daily intake of micro and macro-nutrients were calculated. Bioimpedance analysis was performed five times during the trek; muscle ultrasound was performed before and after the expedition, only for the Italians. The Nepalese group consumed a lot of rice and only Italians consumed cheese. Water intake was slightly over 3000 g/d for both groups. Nepalese diet had a higher density of dietary fibre and lower density of riboflavin, vitamins A, K, and B12. Intake of calcium was lower than recommended levels. Body mass index, waist circumference, fat-free mass, and total body water decreased in both groups, whereas resistance (Rz) increased. Italians reactance (Xc) increased at day 9, whereas that of Nepalese occurred at days 5, 9, and 16. The cross-sectional area of the Vastus lateralis was reduced after the expedition. Specific nutritional and food-related risk factors guidance is needed for diverse expedition groups. Loss of muscle mass and balance of fluids both deserve a particular focus as concerns altitude expeditions.

Serum ferritin and vitamin D evaluation in response to high altitude comparing Italians trekkers vs Nepalese porters.

Altitude hypoxia induces changes in iron homeostasis with serum ferritin (sFER) response being recently linked to erythropoiesis. The main aim of this study was to investigate sFER and Vitamin D (Vit D) response to hypobaric hypoxia, taking into account factors including nutrition and ethnic origin. As part of a "Kanchenjunga Exploration & Physiology" project, 6 Italian trekkers and 6 Nepalese porters took part in a 19-days long altitude trek in the Himalayas self-recording daily food consumption. Blood samples were collected and analyzed before and after the trek for sFER and Vit D. A web-based system calculated the dietary intake, generating reports that were used for later statistical analyses. sFER decreased after the trek (on average by 26% p = 0.013, partial η2 = 0.479) in both groups, whereas Vit D did not change in both groups. Nepalese tended to have lower sFER, but this difference was reduced when corrected for the dietary intake. Mean Cell Volume (MCV) and Hematocrit (HCT), in respect to baseline, remained higher 10 days after the trek (respectively, 87.37-88.85 fL with p = 0.044, and 43.05-44.63% with p = 0.065) in Italian trekkers. The observed reduction of sFER levels was related to altitude per se as inflammation or anemia were medically excluded. sFER, therefore, may act as a primary factor in the examination of hypobaric hypoxia in field studies. The results of this study open a new door into the mechanisms of iron homeostasis in specific tissues related to hypoxia adaptations, taking into account dietary intake and ethnic origin.

Muscle Hypertrophy and Architectural Changes in Response to Eight-Week Neuromuscular Electrical Stimulation Training in Healthy Older People.

Loss of muscle mass of the lower limbs and of the spine extensors markedly impairs locomotor ability and spine stability in old age. In this study, we investigated whether 8 w of neuromuscular electrical stimulation (NMES) improves size and architecture of the lumbar multifidus (LM) and vastus lateralis (VL) along with locomotor ability in healthy older individuals. Eight volunteers (aged 65 ≥ years) performed NMES 3 times/week. Eight sex- and age-matched individuals served as controls. Functional tests (Timed Up and Go test (TUG) and Five Times Sit-to-Stand Test (FTSST)), VL muscle architecture (muscle thickness (MT), pennation angle (PA), and fiber length (FL)), along with VL cross-sectional area (CSA) and both sides of LM were measured before and after by ultrasound. By the end of the training period, MT and CSA of VL increased by 8.6% and 11.4%, respectively. No significant increases were observed in FL and PA. LM CSA increased by 5.6% (left) and 7.1% (right). Interestingly, all VL architectural parameters significantly decreased in the control group. The combined NMES had a large significant effect on TUG (r = 0.50, p = 0.046). These results extend previous findings on the hypertrophic effects of NMES training, suggesting to be a useful mean for combating age-related sarcopenia.

Glucagon-like peptide 1 infusions overcome anabolic resistance to feeding in older human muscle.

BACKGROUND: Despite its known insulin-independent effects, glucagon-like peptide-1 (GLP-1) role in muscle protein turnover has not been explored under fed-state conditions or in the context of older age, when declines in insulin sensitivity and protein anabolism, as well as losses of muscle mass and function, occur. METHODS: Eight older-aged men (71 ± 1 year, mean ± SEM) were studied in a crossover trial. Baseline measures were taken over 3 hr, prior to a 3 hr postprandial insulin (~30 mIU ml-1 ) and glucose (7-7.5 mM) clamp, alongside I.V. infusions of octreotide and Vamin 14 (±infusions of GLP-1). Four muscle biopsies were taken, and muscle protein turnover was quantified via incorporation of 13 C6 phenylalanine and arteriovenous balance kinetics, using mass spectrometry. Leg macro- and microvascular flow was assessed via ultrasound and anabolic signalling by immunoblotting. GLP-1 and insulin were measured by ELISA. RESULTS: GLP-1 augmented muscle protein synthesis (MPS; fasted: 0.058 ± 0.004% hr-1 vs. postprandial: 0.102 ± 0.005% hr-1 , p < 0.01), in comparison with non-GLP-1 trials. Muscle protein breakdown (MPB) was reduced throughout clamp period, while net protein balance across the leg became positive in both groups. Total femoral leg blood flow was unchanged by the clamp; however, muscle microvascular blood flow (MBF) was significantly elevated in both groups, and to a significantly greater extent in the GLP-1 group (MBF: 5 ± 2 vs. 1.9 ± 1 fold change +GLP-1 and -GLP-1, respectively, p < 0.01). Activation of the Akt-mTOR signalling was similar across both trials. CONCLUSION: GLP-1 infusion markedly enhanced postprandial microvascular perfusion and further stimulated muscle protein metabolism, primarily through increased MPS, during a postprandial insulin hyperaminoacidaemic clamp.

The importance of sonographic evaluation of muscle depth and thickness prior to the 'tiny percutaneous needle biopsy'.

Biopsy of human skeletal muscle tissue is a widely used method in many research studies, where 'the tiny percutaneous needle biopsy' (TPNB) is one of the relatively simplest and safest procedures currently available. By using and contrasting ultrasound images of vastus lateralis of young and elderly subjects, this work highlights further the safety aspects of TPNB and stresses the importance of prior ultrasound evaluation of muscle depth and thickness in order to prevent wrong muscle group or tissue sampling in subsequent laboratory analyses.

Demographic and Lifestyle Factors and Memory in European Older People.

OBJECTIVES: To investigate associations between demographic and lifestyle factors and memory performance in European people aged ≥60 years. METHODS: Data from 23,641 people with a mean age of 70.2 (95 % CI 70.1-70.3) were analyzed and drawn from the fourth wave of the Survey of Health, Ageing, and Retirement in Europe (SHARE). Generalized linear models were carried out to estimate the associations for both men and women. Memory performance was tested using two word-list learning tests with immediate and delayed recall in SHARE. RESULTS: age, severe limitations in physical activities, and any past alcohol problem were all negatively associated with memory performance. Contrarily, education level, higher nonalcoholic fluid intake, and engagement in sports activities more than once a week and in activities requiring a moderate level of energy were all positively associated with memory performance. Smoking showed a significant negative association only in the immediate recall test for both men and women together, whilst long-term illness showed association only in the delayed recall. Alcohol consumption was positively associated with memory performance in women, but in men, it depended on the drinking frequency. CONCLUSIONS: Demographic and lifestyle factors are associated with memory performance in the older population.

Sex Hormones Response to Physical Hyperoxic and Hyperbaric Stress in Male Scuba Divers: A Pilot Study.

The use of hyperbaric oxygen plays a significant role in many aspects of medicine. However, there are few studies that analyzed the role of hyperbaric oxygen, in addition to physical exercise, on the endocrine profile. The aim of this study was to compare changes in plasma male sex hormones after hyperbaric physical exercise with different hyperbaric oxygen pre-conditionings. We recruited six healthy, well-trained recreational male divers. Concentrations of prolactin (PRL), follicle-stimulating hormone (FSH), luteotrophic hormone (LH), cortisol, 17-ß estradiol (E2), and total testosterone (TT) were measured in venous blood immediately after four different study conditions. Exercise increased PRL and hyperbaric oxygen potentiated this effect. Hyperbaria stimulated the E2 reduction and hyperoxia partially inhibited this reduction. Hyperbaria, but not hyperoxia, stimulated the TT reduction. There were no changes in FSH, LH, and cortisol. The increase in PRL likely reflects a stress response after physical exercise, amplified by hyperbaric oxygen. TT reduction may be interpreted as an acute and transient fertility impairment. Age, blood pressure, and BMI were taken into account as covariates for statistical analyses, and they significantly affected the results, in particular TT. These data open new insight into the role of E2 and PRL in male endocrine adaptive responses.