Dataset Information

Cold- and exercise-induced peak metabolic rates in tropical birds.

ABSTRACT: Compared with temperate birds, tropical birds have low reproductive rates, slow development as nestlings, and long lifespans. These "slow" life history traits are thought to be associated with reduced energy expenditure, or a slow "pace of life." To test predictions from this hypothesis, we measured exercise-induced peak metabolic rates (PMR(E)) in 45 species of tropical lowland forest birds and compared these data with PMR(E) for three temperate species. We also compared cold-induced PMR (PMR(C)) with PMR(E) in the same individuals of 19 tropical species. Tropical birds had a 39% lower PMR(E) than did the temperate species. In tropical birds, PMR(C) and PMR(E) scaled similarly with body mass (M(b)), but PMR(E) was 47% higher than PMR(C). PMR(E) averaged 6.44 x basal metabolic rate (BMR) and PMR(C) averaged 4.52 x BMR. The slope of the equation relating PMR(E) to M(b) exceeded the slope for the equation for BMR vs. M(b), whereas slopes for the equations of PMR(C) and BMR vs. M(b) did not differ. M(b)-adjusted residuals of PMR(E) were positively correlated with residual BMR, whereas residual PMR(C) and residual BMR were not correlated. PMR(E) and PMR(C) were not correlated after we corrected for M(b). Temperate birds maintained their body temperature at an 8.6 degrees C lower average air temperature than did tropical species. The lower PMR(E) values in tropical species suggest that their suite of life history traits on the slow end of the life history continuum are associated with reduced metabolic rates.

SUBMITTER: Wiersma P

PROVIDER: S-EPMC2409233 | biostudies-literature | 2007 Dec

REPOSITORIES: biostudies-literature

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Cold- and exercise-induced peak metabolic rates in tropical birds.

Wiersma Popko P Chappell Mark A MA Williams Joseph B JB

Proceedings of the National Academy of Sciences of the United States of America 20071218 52

Compared with temperate birds, tropical birds have low reproductive rates, slow development as nestlings, and long lifespans. These "slow" life history traits are thought to be associated with reduced energy expenditure, or a slow "pace of life." To test predictions from this hypothesis, we measured exercise-induced peak metabolic rates (PMR(E)) in 45 species of tropical lowland forest birds and compared these data with PMR(E) for three temperate species. We also compared cold-induced PMR (PMR(C ...[more]

PMID: 18093954

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Project description:BackgroundPhysical activity is an important part of life, and hence exercise-induced bronchoconstriction (EIB) can reduce the quality of life. A standardized test is needed to diagnose EIB. The American Thoracic Society (ATS) guidelines recommend an exercise challenge in combination with dry air. We investigated the feasibility of a new, ATS guidelines conform exercise challenge in a cold chamber (ECC) to detect EIB. The aim of this study was to investigate the surrogate marker reaction to methacholine, ECC and exercise challenge in ambient temperature for the prediction of a positive reaction and to re-evaluate the reproducibility of the response to an ECC.MethodsSeventy-eight subjects aged 6 to 40 years with suspected EIB were recruited for the study. The subjects performed one methacholine challenge, two ECCs, and one exercise challenge at an ambient temperature. To define the sensitivity and specificity of the predictor, a receiver-operating characteristic curve was plotted. The repeatability was evaluated using the method described by Bland and Altman (95% Limits of agreement).ResultsThe following cut-off values showed the best combination of sensitivity and specificity: the provocation dose causing a 20% decrease in the forced expiratory volume in 1 s (PD20FEV1) of methacholine: 1.36 mg (AUC 0.69, p < 0.05), the maximal decrease in FEV1 during the ECC: 8.5% (AUC 0.78, p < 0.001) and exercise challenges at ambient temperatures: FEV1 5.2% (AUC 0.64, p = 0.13). The median decline in FEV1 was 14.5% (0.0-64.2) during the first ECC and 10.7% (0.0-52.5) during the second ECC. In the comparison of both ECCs, the Spearman rank correlation of the FEV1 decrease was r = 0.58 (p < 0.001). The 95% limits of agreement (95% LOAs) for the FEV1 decrease were - 17.7 to 26.4%.ConclusionsThe surrogate markers PD20FEV1 of methacholine and maximal decrease in FEV1 during ECC can predict a positive reaction in another ECC, whereas the maximal FEV1 decrease in an exercise challenge at an ambient temperature was not predictive. Compared with previous studies, we can achieve a similar reproducibility with an ECC.Clinical trial registrationNCT02026492 (retrospectively registered 03/Jan/2014).

Dataset Information

Cold- and exercise-induced peak metabolic rates in tropical birds.

Publications

Cold- and exercise-induced peak metabolic rates in tropical birds.

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