Anabolic resistance of muscle protein turnover comes in various shapes and sizes

Anabolic resistance is defined by a blunted stimulation of muscle protein synthesis rates (MPS) to common anabolic stimuli in skeletal muscle tissue such as dietary protein and exercise. Generally, MPS is the target of most exercise and feeding interventions as muscle protein breakdown rates seem to be less responsive to these stimuli. Ultimately, the blunted responsiveness of MPS to dietary protein and exercise underpins the loss of the amount and quality of skeletal muscle mass leading to decrements in physical performance in these populations. The increase of both habitual physical activity (including structured exercise that targets general fitness characteristics) and protein dense food ingestion are frontline strategies utilized to support muscle mass, performance, and health. In this paper, we discuss anabolic resistance as a common denominator underpinning muscle mass loss with aging, obesity, and other disease states. Namely, we discuss the fact that anabolic resistance exists as a dimmer switch, capable of varying from higher to lower levels of resistance, to the main anabolic stimuli of feeding and exercise depending on the population. Moreover, we review the evidence on whether increased physical activity and targeted exercise can be leveraged to restore the sensitivity of skeletal muscle tissue to dietary amino acids regardless of the population

Exercising to offset muscle mass loss in hemodialysis patients: The disconnect between intention and intervention

Skeletal muscle loss is the most important hallmark of protein energy wasting syndrome as it contributes to declines in physical independence, poor quality of life, and higher mortality risk in individuals with ESRD on maintenance hemodialysis (HD). As such, exercise and nutritional interventions have been investigated with the goal to preserve skeletal muscle mass and overall quality of life. Unfortunately, current efforts are unable to confirm the capacity of exercise to mitigate ESRD‐associated muscle wasting. However, the inconclusive data are often accompanied by suboptimal exercise prescriptions. Exercise sessions are often implemented in‐clinic during the catabolic and proinflammatory period of dialysis treatment and without concurrent nutritional support. Additionally, indirect considerations like exercise intolerance and exercise program compliance/adherence also inhibit exercise training potential. These shortcomings all stem from the current lack of understanding in skeletal muscle mass regulation within the context of ESRD and intermittent HD. As such, this review summarizes the current understanding of exercise regulation on skeletal muscle mass and ESRD‐related obstacles of anabolism to contextualize the ineffectiveness of current exercise interventions for HD patients

Potato Ingestion as an Effective Race Fuel Alternative to Improve Cycling Performance in Trained Cyclists

Carbohydrate (CHO) ingestion is an established strategy to improve endurance performance. Race fuels should not only sustain performance, but also be readily digested and absorbed and replenish electrolytes. Potatoes are a cost-effective option that fulfills these criteria; however, their impact on endurance performance remains unexamined. PURPOSE: Compare the effects of potato purée (POT) ingestion during endurance cycling on subsequent performance versus commercial CHO gel (GEL) or a control (water, CTL). METHODS: Twelve trained cyclists (31±9y; 71±8kg; VO2max: 61±9mL/kg/min) consumed a standardized breakfast then performed a 2h cycling challenge (60-85%VO2max) followed by a time trial (6kJ/kg body mass) while consuming POT, GEL, or CTL in a randomized-crossover design. POT, GEL and CTL were administered with U-[13C6]glucose for an indirect estimate of gastric emptying rate. Repeated blood samples were collected. RESULTS: Time trial performance significantly improved (P=0.03) with POT (33.0±4.5min) and GEL (33.0±4.2min) versus CTL condition (39.5±7.9min); while POT and GEL conditions (P=1.00) had no difference. Post-challenge, blood glucose concentrations were lower (P0.05). CONCLUSION: Potatoes served as a viable alternative to commercial gels by sustaining performance and blood glucose concentrations during endurance cycling events in trained cyclists

NEOTROPICAL XENARTHRANS: a data set of occurrence of xenarthran species in the Neotropics

Xenarthrans—anteaters, sloths, and armadillos—have essential functions for ecosystem maintenance, such as insect control and nutrient cycling, playing key roles as ecosystem engineers. Because of habitat loss and fragmentation, hunting pressure, and conflicts with domestic dogs, these species have been threatened locally, regionally, or even across their full distribution ranges. The Neotropics harbor 21 species of armadillos, 10 anteaters, and 6 sloths. Our data set includes the families Chlamyphoridae (13), Dasypodidae (7), Myrmecophagidae (3), Bradypodidae (4), and Megalonychidae (2). We have no occurrence data on Dasypus pilosus (Dasypodidae). Regarding Cyclopedidae, until recently, only one species was recognized, but new genetic studies have revealed that the group is represented by seven species. In this data paper, we compiled a total of 42,528 records of 31 species, represented by occurrence and quantitative data, totaling 24,847 unique georeferenced records. The geographic range is from the southern United States, Mexico, and Caribbean countries at the northern portion of the Neotropics, to the austral distribution in Argentina, Paraguay, Chile, and Uruguay. Regarding anteaters, Myrmecophaga tridactyla has the most records (n = 5,941), and Cyclopes sp. have the fewest (n = 240). The armadillo species with the most data is Dasypus novemcinctus (n = 11,588), and the fewest data are recorded for Calyptophractus retusus (n = 33). With regard to sloth species, Bradypus variegatus has the most records (n = 962), and Bradypus pygmaeus has the fewest (n = 12). Our main objective with Neotropical Xenarthrans is to make occurrence and quantitative data available to facilitate more ecological research, particularly if we integrate the xenarthran data with other data sets of Neotropical Series that will become available very soon (i.e., Neotropical Carnivores, Neotropical Invasive Mammals, and Neotropical Hunters and Dogs). Therefore, studies on trophic cascades, hunting pressure, habitat loss, fragmentation effects, species invasion, and climate change effects will be possible with the Neotropical Xenarthrans data set. Please cite this data paper when using its data in publications. We also request that researchers and teachers inform us of how they are using these data

NEOTROPICAL ALIEN MAMMALS: a data set of occurrence and abundance of alien mammals in the Neotropics

Biological invasion is one of the main threats to native biodiversity. For a species to become invasive, it must be voluntarily or involuntarily introduced by humans into a nonnative habitat. Mammals were among first taxa to be introduced worldwide for game, meat, and labor, yet the number of species introduced in the Neotropics remains unknown. In this data set, we make available occurrence and abundance data on mammal species that (1) transposed a geographical barrier and (2) were voluntarily or involuntarily introduced by humans into the Neotropics. Our data set is composed of 73,738 historical and current georeferenced records on alien mammal species of which around 96% correspond to occurrence data on 77 species belonging to eight orders and 26 families. Data cover 26 continental countries in the Neotropics, ranging from Mexico and its frontier regions (southern Florida and coastal-central Florida in the southeast United States) to Argentina, Paraguay, Chile, and Uruguay, and the 13 countries of Caribbean islands. Our data set also includes neotropical species (e.g., Callithrix sp., Myocastor coypus, Nasua nasua) considered alien in particular areas of Neotropics. The most numerous species in terms of records are from Bos sp. (n = 37,782), Sus scrofa (n = 6,730), and Canis familiaris (n = 10,084); 17 species were represented by only one record (e.g., Syncerus caffer, Cervus timorensis, Cervus unicolor, Canis latrans). Primates have the highest number of species in the data set (n = 20 species), partly because of uncertainties regarding taxonomic identification of the genera Callithrix, which includes the species Callithrix aurita, Callithrix flaviceps, Callithrix geoffroyi, Callithrix jacchus, Callithrix kuhlii, Callithrix penicillata, and their hybrids. This unique data set will be a valuable source of information on invasion risk assessments, biodiversity redistribution and conservation-related research. There are no copyright restrictions. Please cite this data paper when using the data in publications. We also request that researchers and teachers inform us on how they are using the data