Voluntary Activity

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Theodore Garland - One of the best experts on this subject based on the ideXlab platform.

  • erythropoietin elevates vo2 max but not Voluntary wheel running in mice
    The Journal of Experimental Biology, 2010
    Co-Authors: Erik M Kolb, Scott A Kelly, Kevin M Middleton, L S Sermsakdi, Mark A Chappell, Theodore Garland
    Abstract:

    Voluntary Activity is a complex trait, comprising both behavioral (motivation, reward) and anatomical/physiological (ability) elements. In the present study, oxygen transport was investigated as a possible limitation to further increases in running by four replicate lines of mice that have been selectively bred for high Voluntary wheel running and have reached an apparent selection limit. To increase oxygen transport capacity, erythrocyte density was elevated by the administration of an erythropoietin (EPO) analogue. Mice were given two EPO injections, two days apart, at one of two dose levels (100 or 300 microg kg(-1)). Hemoglobin concentration ([Hb]), maximal aerobic capacity during forced treadmill exercise (VO2,max) and Voluntary wheel running were measured. [Hb] did not differ between high runner (HR) and non-selected control (C) lines without EPO treatment. Both doses of EPO significantly (P<0.0001) increased [Hb] as compared with sham-injected animals, with no difference in [Hb] between the 100 microg kg(-1) and 300 microg kg(-1) dose levels (overall mean of 4.5 g dl(-1) increase). EPO treatment significantly increased VO2,max by approximately 5% in both the HR and C lines, with no dosexline type interaction. However, wheel running (revolutions per day) did not increase with EPO treatment in either the HR or C lines, and in fact significantly decreased at the higher dose in both line types. These results suggest that neither [Hb] per se nor VO2,max is limiting Voluntary wheel running in the HR lines. Moreover, we hypothesize that the decrease in wheel running at the higher dose of EPO may reflect direct action on the reward pathway of the brain.

  • basal metabolic rate of aged mice is affected by random genetic drift but not by selective breeding for high early age locomotor Activity or chronic wheel access
    Physiological and Biochemical Zoology, 2008
    Co-Authors: Stephanie L Kane, Theodore Garland, Patrick A. Carter
    Abstract:

    Abstract The study of correlated evolution can lead to new insights about the inheritance patterns of complex traits. In order to better understand the evolution of metabolic rate, we tested whether Voluntary Activity levels and basal metabolic rate are genetically correlated in 90‐wk‐old mice (Mus domesticus) from replicated lines of the sixteenth generation of an artificial selection experiment for high early‐age wheel‐running Activity. We measured basal rates of oxygen consumption and carbon dioxide production and also computed the respiratory exchange ratio. Half of the individuals from both selected and control lines had been allowed free access to running wheels since 4 wk of age, while the other half were in standard cages. This design allowed testing of hypotheses about (1) genetic correlations between Voluntary Activity and metabolic rate and (2) lifetime training effects on metabolic traits. Selection group did not have a significant effect on metabolic traits; therefore, this study does not sup...

  • effects of Voluntary Activity and genetic selection on muscle metabolic capacities in house mice mus domesticus
    Journal of Applied Physiology, 2000
    Co-Authors: Philippe Houleleroy, John G Swallow, Theodore Garland, Helga Guderley
    Abstract:

    Selective breeding is an important tool in behavioral genetics and evolutionary physiology, but it has rarely been applied to the study of exercise physiology. We are using artificial selection for...

  • Nesting Behavior of House Mice (Mus Domesticus) Selected for Increased Wheel-Running Activity
    Behavior Genetics, 2000
    Co-Authors: Patrick A. Carter, John G Swallow, Sarah J. Davis, Theodore Garland
    Abstract:

    Nest building was measured in “active” (housed with access to running wheels) and “sedentary” (without wheel access) mice (Mus domesticus) from four replicate lines selected for 10 generations for high Voluntary wheel-running behavior, and from four randombred control lines. Based on previous studies of mice bidirectionally selected for thermoregulatory nest building, it was hypothesized that nest building would show a negative correlated response to selection on wheel-running. Such a response could constrain the evolution of high Voluntary Activity because nesting has also been shown to be positively genetically correlated with successful production of weaned pups. With wheel access, selected mice of both sexes built significantly smaller nests than did control mice. Without wheel access, selected females also built significantly smaller nests than did control females, but only when body mass was excluded from the statistical model, suggesting that body mass mediated this correlated response to selection. Total distance run and mean running speed on wheels was significantly higher in selected mice than in controls, but no differences in amount of time spent running were measured, indicating a complex cause of the response of nesting to selection for Voluntary wheel running.

  • effects of Voluntary Activity and genetic selection on aerobic capacity in house mice mus domesticus
    Journal of Applied Physiology, 1998
    Co-Authors: John G Swallow, Wen Zhi Zhan, Theodore Garland, Patrick A. Carter, Gary C. Sieck
    Abstract:

    Swallow, John G., Theodore Garland, Jr., Patrick A. Carter, Wen-Zhi Zhan, and Gary C. Sieck. Effects of Voluntary Activity and genetic selection on aerobic capacity in house mice (Mus domesticus).J...

Patrick A. Carter - One of the best experts on this subject based on the ideXlab platform.

  • basal metabolic rate of aged mice is affected by random genetic drift but not by selective breeding for high early age locomotor Activity or chronic wheel access
    Physiological and Biochemical Zoology, 2008
    Co-Authors: Stephanie L Kane, Theodore Garland, Patrick A. Carter
    Abstract:

    Abstract The study of correlated evolution can lead to new insights about the inheritance patterns of complex traits. In order to better understand the evolution of metabolic rate, we tested whether Voluntary Activity levels and basal metabolic rate are genetically correlated in 90‐wk‐old mice (Mus domesticus) from replicated lines of the sixteenth generation of an artificial selection experiment for high early‐age wheel‐running Activity. We measured basal rates of oxygen consumption and carbon dioxide production and also computed the respiratory exchange ratio. Half of the individuals from both selected and control lines had been allowed free access to running wheels since 4 wk of age, while the other half were in standard cages. This design allowed testing of hypotheses about (1) genetic correlations between Voluntary Activity and metabolic rate and (2) lifetime training effects on metabolic traits. Selection group did not have a significant effect on metabolic traits; therefore, this study does not sup...

  • Nesting Behavior of House Mice (Mus Domesticus) Selected for Increased Wheel-Running Activity
    Behavior Genetics, 2000
    Co-Authors: Patrick A. Carter, John G Swallow, Sarah J. Davis, Theodore Garland
    Abstract:

    Nest building was measured in “active” (housed with access to running wheels) and “sedentary” (without wheel access) mice (Mus domesticus) from four replicate lines selected for 10 generations for high Voluntary wheel-running behavior, and from four randombred control lines. Based on previous studies of mice bidirectionally selected for thermoregulatory nest building, it was hypothesized that nest building would show a negative correlated response to selection on wheel-running. Such a response could constrain the evolution of high Voluntary Activity because nesting has also been shown to be positively genetically correlated with successful production of weaned pups. With wheel access, selected mice of both sexes built significantly smaller nests than did control mice. Without wheel access, selected females also built significantly smaller nests than did control females, but only when body mass was excluded from the statistical model, suggesting that body mass mediated this correlated response to selection. Total distance run and mean running speed on wheels was significantly higher in selected mice than in controls, but no differences in amount of time spent running were measured, indicating a complex cause of the response of nesting to selection for Voluntary wheel running.

  • effects of Voluntary Activity and genetic selection on aerobic capacity in house mice mus domesticus
    Journal of Applied Physiology, 1998
    Co-Authors: John G Swallow, Wen Zhi Zhan, Theodore Garland, Patrick A. Carter, Gary C. Sieck
    Abstract:

    Swallow, John G., Theodore Garland, Jr., Patrick A. Carter, Wen-Zhi Zhan, and Gary C. Sieck. Effects of Voluntary Activity and genetic selection on aerobic capacity in house mice (Mus domesticus).J...

  • effects of Voluntary Activity and genetic selection on aerobic capacity in house mice mus domesticus
    Journal of Applied Physiology, 1998
    Co-Authors: John G Swallow, Wen Zhi Zhan, Theodore Garland, Patrick A. Carter, Gary C. Sieck
    Abstract:

    Swallow, John G., Theodore Garland, Jr., Patrick A. Carter, Wen-Zhi Zhan, and Gary C. Sieck. Effects of Voluntary Activity and genetic selection on aerobic capacity in house mice (Mus domesticus).J...

Janet L Taylor - One of the best experts on this subject based on the ideXlab platform.

  • time course of human motoneuron recovery after sustained low level Voluntary Activity
    Journal of Neurophysiology, 2016
    Co-Authors: Martin E Heroux, Janet L Taylor, Simon C Gandevia, Annie A Butler, Jane E Butler
    Abstract:

    Motoneurons often fire repetitively and for long periods. In sustained Voluntary contractions the excitability of motoneurons declines. We provide the first detailed description of the time course ...

  • the origin of Activity in the biceps brachii muscle during Voluntary contractions of the contralateral elbow flexor muscles
    Experimental Brain Research, 2006
    Co-Authors: Inge Zijdewind, Jane E Butler, Simon C Gandevia, Janet L Taylor
    Abstract:

    During strong Voluntary contractions, Activity is not restricted to the target muscles. Other muscles, including contralateral muscles, often contract. We used transcranial magnetic stimulation (TMS) to analyse the origin of these unintended contralateral contractions (termed “associated” contractions). Subjects (n = 9) performed maximal Voluntary contractions (MVCs) with their right elbow-flexor muscles followed by submaximal contractions with their left elbow flexors. Electromyographic Activity (EMG) during the submaximal contractions was matched to the associated EMG in the left biceps brachii during the right MVC. During contractions, TMS was delivered to the motor cortex of the right or left hemisphere and excitatory motor evoked potentials (MEPs) and inhibitory (silent period) responses recorded from left biceps. Changes at a spinal level were investigated using cervicomedullary stimulation to activate corticospinal paths (n = 5). Stimulation of the right hemisphere produced silent periods of comparable duration in associated and Voluntary contractions (218 vs 217 ms, respectively), whereas left hemisphere stimulation caused a depression of EMG but no EMG silence in either contraction. Despite matched EMG, MEPs elicited by right hemisphere stimulation were ∼1.5–2.5 times larger during associated compared to Voluntary contractions (P < 0.005). Similar inhibition of the associated and matched Voluntary Activity during the silent period suggests that associated Activity comes from the contralateral hemisphere and that motor areas in this (right) hemisphere are activated concomitantly with the motor areas in the left hemisphere. Comparison of the MEPs and subcortically evoked potentials implies that cortical excitability was greater in associated contractions than in the matched Voluntary efforts.

  • the origin of Activity in the biceps brachii muscle during Voluntary contractions of the contralateral elbow flexor muscles
    Experimental Brain Research, 2006
    Co-Authors: Inge Zijdewind, Jane E Butler, Simon C Gandevia, Janet L Taylor
    Abstract:

    During strong Voluntary contractions, Activity is not restricted to the target muscles. Other muscles, including contralateral muscles, often contract. We used transcranial magnetic stimulation (TMS) to analyse the origin of these unintended contralateral contractions (termed "associated" contractions). Subjects (n = 9) performed maximal Voluntary contractions (MVCs) with their right elbow-flexor muscles followed by submaximal contractions with their left elbow flexors. Electromyographic Activity (EMG) during the submaximal contractions was matched to the associated EMG in the left biceps brachii during the right MVC. During contractions, TMS was delivered to the motor cortex of the right or left hemisphere and excitatory motor evoked potentials (MEPs) and inhibitory (silent period) responses recorded from left biceps. Changes at a spinal level were investigated using cervicomedullary stimulation to activate corticospinal paths (n = 5). Stimulation of the right hemisphere produced silent periods of comparable duration in associated and Voluntary contractions (218 vs 217 ms, respectively), whereas left hemisphere stimulation caused a depression of EMG but no EMG silence in either contraction. Despite matched EMG, MEPs elicited by right hemisphere stimulation were approximately 1.5-2.5 times larger during associated compared to Voluntary contractions (P < 0.005). Similar inhibition of the associated and matched Voluntary Activity during the silent period suggests that associated Activity comes from the contralateral hemisphere and that motor areas in this (right) hemisphere are activated concomitantly with the motor areas in the left hemisphere. Comparison of the MEPs and subcortically evoked potentials implies that cortical excitability was greater in associated contractions than in the matched Voluntary efforts.

John G Swallow - One of the best experts on this subject based on the ideXlab platform.

Jj Ramsey - One of the best experts on this subject based on the ideXlab platform.

  • Sex‐specific alterations in whole body energetics and Voluntary Activity in heterozygous R163C malignant hyperthermia‐susceptible mice
    'FASEB', 2020
    Co-Authors: Jm Rutkowsky, Pd Allen, Ta Knotts, In Pessah, Jj Ramsey
    Abstract:

    Malignant hyperthermia (MH) is characterized by induction of skeletal muscle hyperthermia in response to a dysregulated increase in myoplasmic calcium. Although altered energetics play a central role in MH, MH‐susceptible humans and mouse models are often described as having no phenotype until exposure to a triggering agent. The purpose of this study was to determine the influence of the R163C ryanodine receptor 1 mutation, a common MH mutation in humans, on energy expenditure, and Voluntary wheel running in mice. Energy expenditure was measured by indirect respiration calorimetry in wild‐type (WT) and heterozygous R163C (HET) mice over a range of ambient temperatures. Energy expenditure adjusted for body weight or lean mass was increased (P < .05) in male, but not female, HET mice housed at 22°C or when housed at 28°C with a running wheel. In female mice, Voluntary wheel running was decreased (P < .05) in the HET vs WT animals when analyzed across ambient temperatures. The thermoneutral zone was also widened in both male and female HET mice. The results of the study show that the R163C mutations alters energetics even at temperatures that do not typically induce MH

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