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Prediction of maximal or peak oxygen uptake from ratings of perceived exertion.
Coquart, JB, Garcin, M, Parfitt, G, Tourny-Chollet, C, Eston, RG
Sports medicine (Auckland, N.Z.). 2014;(5):563-78
Abstract
Maximal or peak oxygen uptake (V˙O2 max and V˙O2 peak , respectively) are commonly measured during graded exercise tests (GXTs) to assess cardiorespiratory fitness (CRF), to prescribe exercise intensity and/or to evaluate the effects of training. However, direct measurement of CRF requires a GXT to volitional exhaustion, which may not always be well accepted by athletes or which should be avoided in some clinical populations. Consequently, numerous studies have proposed various sub-maximal exercise tests to predict V˙O2 max or V˙O2 peak . Because of the strong link between ratings of perceived exertion (RPE) and oxygen uptake (V˙O2), it has been proposed that the individual relationship between RPE and V˙O2 (RPE:V˙O2) can be used to predict V˙O2 max (or V˙O2 peak) from data measured during submaximal exercise tests. To predict V˙O2 max or V˙O2 peak from these linear regressions, two procedures may be identified: an estimation procedure or a production procedure. The estimation procedure is a passive process in which the individual is typically asked to rate how hard an exercise bout feels according to the RPE scale during each stage of a submaximal GXT. The production procedure is an active process in which the individual is asked to self-regulate and maintain an exercise intensity corresponding to a prescribed RPE. This procedure is referred to as a perceptually regulated exercise test (PRET). Recently, prediction of V˙O2max or V˙O2 peak from RPE:V˙O2 measured during both GXT and PRET has received growing interest. A number of studies have tested the validity, reliability and sensitivity of predicted V˙O2 max or V˙O2 peak from RPE:V˙O2 extrapolated to the theoretical V˙O2 max at RPE20 (or RPE19). This review summarizes studies that have used this predictive method during submaximal estimation or production procedures in various populations (i.e., sedentary individuals, athletes and pathological populations). The accuracy of the methods is discussed according to the RPE:V˙O2 range used to plot the linear regression (e.g., RPE9–13 versus RPE9–15 versus RPE9–17 during PRET), as well as the perceptual endpoint used for the extrapolation (i.e., RPE19 and RPE20). The V˙O2 max or V˙O2 peak predictions from RPE:V˙O2 are also compared with heart rate-related predictive methods. This review suggests that V˙O2 max (or V˙O2 peak ) may be predicted from RPE:V˙O2 extrapolated to the theoretical V˙O2 max (or V˙O2 peak) at RPE20 (or RPE19). However, it is generally preferable to (1) extrapolate RPE:V ˙ O 2 to RPE19 (rather than RPE20); (2) use wider RPE ranges (e.g. RPE ≤ 17 or RPE9–17) in order to increase the accuracy of the predictions; and (3) use RPE ≤ 15 or RPE9–15 in order to reduce the risk of cardiovascular complications in clinical populations.
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The neurocognitive bases of human multimodal food perception: consciousness.
Verhagen, JV
Brain research reviews. 2007;(2):271-86
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Abstract
This review explores how we become aware of the (integrated) flavor of food. In recent years, progress has been made understanding the neural correlates of consciousness. Experimental and computational data have been largely based on the visual system. Contemporary neurobiological frameworks of consciousness are reviewed, concluding that neural reverberation among forward- and back-projecting neural ensembles across brain areas is a common theme. In an attempt to extrapolate these concepts to the oral-sensory and olfactory systems involved with multimodal flavor perception, the integration of the sensory information of which into a flavor gestalt has been reviewed elsewhere (Verhagen, J.V., Engelen, L., 2006. The neurocognitive bases of human multimodal food perception: Sensory integration. Neurosci. Biobehav. Rev. 30(5): 613_650), I reconceptualize the flavor-sensory system by integrating it into a larger neural system termed the Homeostatic Interoceptive System (HIS). This system consists of an oral (taste, oral touch, etc.) and non-oral part (non oral-thermosensation, pain, etc.) which are anatomically and functionally highly similar. Consistent with this new concept and with a large volume of experimental data, I propose that awareness of intraoral food is related to the concomitant reverberant self-sustained activation of a coalition of neuronal subsets in agranular insula and orbitofrontal cortex (affect, hedonics) and agranular insula and perirhinal cortex (food identity), as well as the amygdala (affect and identity) in humans. I further discuss the functional anatomy in relation essential nodes. These formulations are by necessity to some extent speculative.
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[Voltage-dependent calcium channels at the heart of pain perception].
Weiss, N, De Waard, M
Medecine sciences : M/S. 2006;(4):396-404
Abstract
Voltage-dependent calcium channels represent a major pathway of calcium entry into neurons, where they participate actively to cell excitability and to the molecular processes of synaptic transmission. For that reason, they have been the direct or indirect pharmacological targets of analgesics and this long before their implication in the physiology of nociception had been demonstrated. These last years, the still more refined molecular characterization of these channels and their associated regulatory subunits and the demonstration of their implication in nociceptive processes indicates that these structures are prime pharmacological targets for the management of pain. Herein, we detail the recent breakthroughs on calcium channel structure, function and pharmacology, review the implication of calcium channels in the transmission of nociception, and evaluate their importance as targets for the treatment of pain perception. The search for specific inhibitors of voltage-dependent calcium channels appears as a prelude to the development of new promising analgesic molecules.
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Effect of sensory perception of foods on appetite and food intake: a review of studies on humans.
Sørensen, LB, Møller, P, Flint, A, Martens, M, Raben, A
International journal of obesity and related metabolic disorders : journal of the International Association for the Study of Obesity. 2003;(10):1152-66
Abstract
OBJECTIVE How much do the sensory properties of food influence the way people select their food and how much they eat? The objective of this paper is to review results from studies investigating the link between the sensory perception of food and human appetite regulation. CONTENT OF THE REVIEW The influence of palatability on appetite and food intake in humans has been investigated in several studies. All reviewed studies have shown increased intake as palatability increased, whereas assessments of the effect of palatability using measures of subjective appetite sensations have shown diverging results, for example, subjects either feel more hungry and less full after a palatable meal compared to a less palatable meal, or they feel the opposite, or there is no difference. Whether palatability has an effect on appetite in the period following consumption of a test meal is unclear. Several studies have investigated which sensory properties of food are involved in sensory-specific satiety. Taste, smell, texture and appearance-specific satieties have been identified, whereas studies on the role of macronutrients and the energy content of the food in sensory-specific satiety have given equivocal results. Different studies have shown that macronutrients and energy content play a role in sensory-specific satiety or that macronutrients and energy content are not a factor in sensory-specific satiety. Sensory-specific satiety may have an important influence on the amount of food eaten. Studies have shown that increasing the food variety can increase food and energy intake and in the short to medium term alter energy balance. Further knowledge about the importance of flavour in appetite regulation is needed, for example, which flavour combinations improve satiety most, the possible connection between flavour intensity and satiety, the effect of persistence of chemesthetic sensation on palatability and satiety, and to what extent genetic variation in taste sensitivity and perception influences dietary habits and weight control.
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Central role of hypothalamic digoxin in conscious perception, neuroimmunoendocrine integration, and coordination of cellular function: relation to hemispheric dominance.
Kurup, RK, Kurup, PA
The International journal of neuroscience. 2002;(6):705-39
Abstract
Alteration in the isoprenoid metabolites--digoxin, ubiquinone, and dolichol--have been reported in neuronal degeneration (Parkinson's disease), oncogenesis (central nervous system glioma), functional neuropsychiatric disorders (schizophrenia and epilepsy), and immune-mediated disorders (multiple sclerosis). The coexistence of these disorders has been documented in literature and a central dysfunction related to digoxin and the isoprenoid pathway may underlie all these disorders. A family with a high prevalence of Parkinson's disease, schizophrenia, neoplasms, syndrome X, rheumatoid arthritis, and epilepsy has been described. The psychological behavioral patterns of the family were: creativity and high IQ, hypersexual behavior, reduced appetite and eating behavior, insomnia and reduced sleep patterns, increased tendency for spirituality, increased tendency for addiction, less bonding and affectionate behavior, and left handedness/right hemispheric dominance. Digoxin, an endogenous Na(+)-K+ ATPase inhibitor secreted by the hypothalamus, was found to be elevated and red blood cell (RBC) membrane Na(+)-K+ ATPase activity was found to be reduced in all the disorders and in the indexed family studied. Hypothalamic digoxin can modulate conscious perception and its dysfunction may lead to schizophrenia. Digoxin can also preferentially upregulate tryptophan transport over tyrosine, resulting in increased levels of depolarizng tryptophan catabolites, serotonin, quinolinic acid, strychnine, and nicotine, and decreased levels of hyperpolarizing tyrosine catabolites, dopamine, noradrenaline, and morphine, contributing to membrane Na(+)-K+ ATPase inhibition in all the above disorders and the indexed family. Digoxin-induced membrane Na(+)-K+ ATPase inhibition can result in increased intracellular Ca2+ and reduced Mg2+ levels, leading on to glutamate excitotoxicity, oncogene activation, and immune activation. Digoxin-induced altered Ca2+/Mg2+ ratios, reduced ubiquinone, and increased dolichol can affect glycoconjugate metabolism, membrane formation and structure, and mitochondrial function, leading to the diverse disorders described above, including those in the indexed family. The isoprenoid pathway and neurotransmitter patterns were compared in right-handed/LH dominant and left-handed/RH dominant individuals. The left-handed/RH dominant individuals compared to right-handed/LH dominant individuals had elevated hydroxymethylglutarylcoenzyme A reductase activity, with increased serum digoxin and dolichol levels. The serum ubiquinone, serum Mg2+ and RBC Na(+)-K+ ATPase activity were reduced in left-handed/RH dominant individuals. The left-handed/RH dominant individuals compared to right-handed/LH dominant individuals had elevated levels of serum tryptophan, quinolinic acid, serotonin, nicotine, and strychnine. The levels of tyrosine, dopamine, noradrenaline, and morphine were low in left-handed/RH dominant compared to right-handed/LH dominant individuals. The hyperdigoxinemic state indicates right hemispheric dominance. Hypothalamic digoxin can thus function as the master conductor of the neuroimmunoendocrine orchestra and coordinate the functions of various cellular organelles.