ABSTRACT
Rediscovery of cold-activated brown adipose tissue (BAT) in humans has boosted research interest in identifying BAT activators for metabolic benefits. Of particular interest are cytokines capable of fat browning. Irisin, derived from FNDC5, is an exercise-induced myokine that drives brown-fat-like thermogenesis in murine white fat. Here we explored whether cold exposure is an afferent signal for irisin secretion in humans and compared it with FGF21, a brown adipokine in rodents. Cold exposure increased circulating irisin and FGF21. We found an induction of irisin secretion proportional to shivering intensity, in magnitude similar to exercise-stimulated secretion. FNDC5 and/or FGF21 treatment upregulated human adipocyte brown fat gene/protein expression and thermogenesis in a depot-specific manner. These results suggest exercise-induced irisin secretion could have evolved from shivering-related muscle contraction, serving to augment brown fat thermogenesis in concert with FGF21. Irisin-mediated muscle-adipose crosstalk may represent a thermogenic, cold-activated endocrine axis that is exploitable in obesity therapeutics development.
Subject(s)
Exercise/physiology , Fibroblast Growth Factors/blood , Fibronectins/blood , Adipocytes/metabolism , Adipokines/metabolism , Adipose Tissue, Brown/metabolism , Adult , Female , Fibroblast Growth Factors/metabolism , Fibronectins/metabolism , Humans , Male , Shivering/physiology , Young AdultABSTRACT
Vitamin D deficiency and its adverse skeletal sequelae are well recognized in the general population. Recent observation of high prevalence of low vitamin D states and their associations with worse clinical outcomes in critically ill populations have sparked interest in the role of supplementation for these patients. High-dose vitamin D efficaciously increases serum levels, but its impact on clinical outcome has not been examined. This article will review results from observational studies on prevalence and outcomes of hypovitaminosis D in critically ill patients, as well as caveats of vitamin D interventional trials. Improved understanding of vitamin D metabolism in critical illness will clarify the therapeutic potential of this pleiotropic hormone and facilitate implementation of cost-effective clinical trials.
Subject(s)
Vitamin D Deficiency/therapy , Vitamin D/administration & dosage , Critical Illness , Dietary Supplements , Humans , Treatment Outcome , Vitamin D/metabolism , Vitamin D Deficiency/complications , Vitamin D Deficiency/metabolismABSTRACT
The purpose of this study was to compare treadmill walking with exergame play on the "EA Sports Active™" (Entertainment Arts, Redwood City, CA) for the Nintendo™ (Kyoto, Japan) Wii™. Thirty healthy adults (13 male, 17 female; 24.1±6.6 years old) spent 30 minutes walking briskly on a treadmill and approximately 40 minutes playing "Island Cardio Blast" on "EA Sports Active." Heart rate (HR) monitors, accelerometers, and Ratings of Perceived Exertion (RPE) were used to measure intensity. Participants also rated affect measures with the Feeling Scale and the Felt Arousal Scale and completed the Physical Activity Enjoyment Scale following completion of exercise. Participants had a significantly higher HR and RPE on the exergame but a higher percentage of minutes in moderate- or higher-intensity activity on the treadmill. Affect measures were consistent with past research, with positive affect following exercise in both conditions. Play on the "EA Sports Active" game for the Nintendo Wii elicited higher HR, RPE, and enjoyment measures than treadmill walking, indicating that it may be a good mode of exercise.
ABSTRACT
The purpose of this study was to determine if two popular exergames, Wii Fit™ and EA Sports Active™, both games for the Nintendo Wii™ console, help children achieve intensity consistent with recommended physical activity guidelines. Thirty children (19 males and 11 females, Mean age = 9.4 ± 1.8 years) participated in this study by playing each game during one research session. During the session participants wore a heart rate monitor and accelerometer to measure exercise intensity. Perceived exertion (RPE) was measured with the children's run/walk OMNI scale. All three measures of exercise intensity (heart rate, accelerometer counts, and RPE) found that the EA Sports Active™ game session elicited higher exercise intensity. However, heart rate data found both games to achieve moderate intensity (65-68% age-predicted HRmax). When using heart rate as an indicator of exercise intensity it appears that both exergames were of sufficient intensity to achieve physical activity guidelines. Future studies should continue to investigate the utility of exergaming in helping children to become more physically active.
