Efecto agudo de ejercicio isométrico sobre parámetros autonómicos en adultos sedentarios obesos y con sobrepeso

Introduction: Obesity is understood as a chronic inflammation associated with complications in the autonomic nervous system dysfunction related to cardiovascular diseases. And isometric exercise, represented by manual grip strength, favors the reduction of cardiovascular risk and autonomic imbalance. Objective: to describe the acute response of an isometric exercise (IE) compared to the effect of an aerobic exercise (AE), analyzing the autonomic parameters of heart rate variability (LF/HF), diastolic blood pressure (DBP), systolic blood pressure (SBP) and heart rate (HR) in obese and overweight people. Methodology: 20 participants were randomly distributed into 2 groups; those who performed an aerobic exercise session on a cycle ergometer for 15 min at 50 watts (n=10) and those who performed an IE session at 30% of maximal strength (n=10). Both were evaluated pre and post intervention, the variables were analyzed using the Mann-Whitney U statistical test with a significance level of p<0.05. Results: IE produced statistically significant changes in SBP (p= 0.001), LH/HF (p=0.02) and HR (p=0.018), while DBP improved, but not significantly. Conclusions: an EI session generates a greater decrease than EA in HRV, HR and SBP variables.Introducción: La obesidad es entendida como una inflamación crónica asociada a complicaciones en la disfunción del sistema nervioso autónomo relacionada con enfermedades cardiovasculares. Y el ejercicio isométrico, representado por la fuerza de prensión manual, favorece la reducción del riesgo cardiovascular y al desequilibrio autonómico. Objetivo: describir la respuesta aguda de un ejercicio isométrico (EI) comparándolo con el efecto de un ejercicio aeróbico (EA), analizando los parámetros autonómicos de variabilidad de la frecuencia cardiaca (LF/HF), presión arterial diastólica (PAD), sistólica (PAS) y la frecuencia cardiaca (FC) en personas obesos y en sobrepeso. Metodología: 20 participantes fueron distribuidos al azar en 2 grupos; los que realizaron una sesión de ejercicio aeróbico en cicloergómetro durante 15 min a 50 watts (n=10) y los que realizaron una sesión de EI al 30% de la fuerza máxima. Ambos fueron evaluados pre y post intervención, se analizaron las variables mediante la prueba estadística U de Mann-Whitney con un nivel de significancia p<0,05. Resultados: El EI produjo cambios estadísticamente significativos en PAS (p= 0,001), LH/HF (p = 0,02) y FC (p=0,01), mientras que la PAD mejoró, pero no de forma significativa. Conclusiones: una sesión de EI, genera una mayor disminución que el EA en las variables de VFC, FC y PAS

Extremely Long-Lived Stigmas Allow Extended Cross-Pollination Opportunities in a High Andean Plant

High-elevation ecosystems are traditionally viewed as environments in which predominantly autogamous breeding systems should be selected because of the limited pollinator availability. Chaetanthera renifolia (Asteraceae) is an endemic monocarpic triennial herb restricted to a narrow altitudinal range within the high Andes of central Chile (3300–3500 m a.s.l.), just below the vegetation limit. This species displays one of the larger capitulum within the genus. Under the reproductive assurance hypothesis, and considering its short longevity (monocarpic triennial), an autogamous breeding system and low levels of pollen limitation would be predicted for C. renifolia. In contrast, considering its large floral size, a xenogamous breeding system, and significant levels of pollen limitation could be expected. In addition, the increased pollination probability hypothesis predicts prolonged stigma longevity for high alpine plants. We tested these alternative predictions by performing experimental crossings in the field to establish the breeding system and to measure the magnitude of pollen limitation in two populations of C. renifolia. In addition, we measured the stigma longevity in unpollinated and open pollinated capitula, and pollinator visitation rates in the field. We found low levels of self-compatibility and significant levels of pollen limitation in C. renifolia. Pollinator visitation rates were moderate (0.047–0.079 visits per capitulum per 30 min). Although pollinator visitation rate significantly differed between populations, they were not translated into differences in achene output. Finally, C. renifolia stigma longevity of unpollinated plants was extremely long and significantly higher than that of open pollinated plants (26.3±2.8 days vs. 10.1±2.2, respectively), which gives support to the increased pollination probability hypothesis for high-elevation flowering plants. Our results add to a growing number of studies that show that xenogamous breeding systems and mechanisms to increase pollination opportunities can be selected in high-elevation ecosystems

Acute effect of isometric exercise on autonomic parameters in obese and overweight sedentary adults

La obesidad es entendida como una inflamación crónica asociada a complicaciones en la disfunción del sistema nervioso autónomo relacionadacon enfermedades cardiovasculares. Y el ejercicio isométrico, representado por la fuerza de prensión manual, favorece la reducción del riesgo cardiovascular y al desequilibrio autonómico. Objetivo:describir la respuesta aguda de un ejercicio isométrico (EI) comparándolo con el efecto de un ejercicio aeróbico (EA), analizando los parámetros autonómicos de variabilidad de la frecuencia cardiaca (LF/HF), presión arterial diastólica (PAD), sistólica (PAS) y la frecuencia cardiaca (FC) en personas obesos y en sobrepeso. Metodología: 20 participantes fueron distribuidos al azar en 2 grupos; los que realizaron una sesión de ejercicio aeróbico en cicloergómetro durante 15 min a 50 watts (n=10) y los que realizaron una sesión de EI al 30% de la fuerza máxima. Ambosfueron evaluados pre y post intervención, se analizaron las variables mediante la prueba estadística U de Mann-Whitney con un nivel designificancia p<0,05.Resultados: El EI produjo cambios estadísticamente significativos en PAS (p= 0,001), LH/HF (p = 0,02) y FC (p=0,01), mientras que la PAD mejoró, pero no de forma significativa. Conclusiones: una sesión de EI, genera una mayor disminución que el EA en las variables de VFC, FC y PAS.Obesity is understood as a chronic inflammation associated with complications in the autonomic nervous system dysfunction related to cardiovascular diseases. And isometric exercise, represented by manual grip strength,favors the reduction of cardiovascular risk and autonomic imbalance. Objective: todescribe the acute response of an isometric exercise (IE) compared to the effect of an aerobic exercise (AE), analyzing the autonomic parameters of heart rate variability (LF/HF), diastolic blood pressure (DBP), systolic blood pressure (SBP) and heart rate (HR) in obese and overweight people. Methodology: 20 participants were randomly distributed into 2 groups; those who performed an aerobic exercise session on a cycle ergometer for 15 min at 50 watts (n=10) and those who performed an IE session at 30% of maximal strength (n=10). Both were evaluated pre and post intervention, the variables were analyzed using the Mann-Whitney U statistical test with a significance level of p<0.05. Results: IE produced statistically significant changes in SBP (p= 0.001), LH/HF (p=0.02) and HR (p=0.018), while DBP improved, but not significantly. Conclusions:an EI session generates a greater decrease than EA in HRV, HR and SBP variables

Effects of pollination treatment on the reproduction of two populations of <i>Chaetanthera renifolia</i>.

<p>ANCOVA summary of effects of pollination treatment (autonomous self-pollination vs. hand cross-pollination) and site (La Parva and Piedra Numerada) on the percentage of achene set and achene weight of <i>Chaetanthera renifolia</i> plants. Plant size (diameter) was entered as a covariate. Significant effects are indicated in bold.</p

Pollinator visitation rates and achene output of two populations of <i>Chaetanthera renifolia</i>.

<p>(A) Mean pollinator visitation rate at La Parva (light-grey bars, <i>n</i> = 18) and Piedra Numerada (dark-grey bars, <i>n</i> = 17). (B) Mean percentage of achene set at La Parva (n = 40) and Piedra Numerada (<i>n</i> = 41). Bars are means ± SE. *** Indicates significant differences (<i>P</i><0.01).</p

Effects of pollination treatment and site on stigmas longevity of <i>Chaetanthera renifolia</i>.

<p>Two-way ANOVA of the effects of treatment (pollinator-excluded vs. open-pollinated) and site (La Parva and Piedra Numerada) on stigma longevity (# days) of <i>Chaetanthera renifolia</i> capitula. Significant effects are indicated in bold.</p

Effects of pollination treatments (spontaneous self-pollination vs. hand cross-pollination) on reproduction of <i>Chaetanthera renifolia</i>.

<p>Mean percentage of achene set and achene weight at La Parva (A and C) and Piedra Numerada (C and D). Open bars: autogamous self-pollinated (<i>n</i> = 18); Grey bars: hand cross-pollination (<i>n</i> = 18). Bars are means ± SE. *** Indicates significant differences (<i>P</i><0.001).</p

List and frequencies of insect pollinator taxa observed on <i>Chaetanthera renifolia</i> capitula.

<p>Number of individuals of each taxon observed (<i>N</i>), and percentage (%) of the total number of visits that each pollinator taxon made to <i>Chaetanthera renifolia</i> capitula from La Parva and Piedra Numerada.</p

Effect of pollination (unpollinated vs. open-pollinated) on stigma longevity of <i>Chaetanthera renifolia</i>.

<p>Mean stigma longevity of open-pollinated (white bars, <i>n</i> = 18) and pollinator–excluded plants (grey bars, <i>n</i> = 18) at La Parva (A) and Piedra Numerada (B) populations of <i>Chaetanthera renifolia</i>. Bars are means ± SE. *** Indicates significant differences (<i>P</i><0.01).</p