Effect of exercise on hepatic steatosis: Are benefits seen without dietary intervention? A systematic review and meta-analysis.

BACKGROUND: Interventions involving both exercise and dietary modification are effective in reducing steatosis in nonalcoholic fatty liver disease (NAFLD). However, exercise alone may reduce liver fat and is known to have other positive effects on health. The primary aim of this study was to systematically review the effect of exercise alone without dietary intervention on NAFLD and to examine correlations across changes in liver fat and metabolic markers during exercise. METHODS: Relevant online databases were searched from earliest records to May 2020 by two researchers. Studies were included where the trial was a randomized controlled trial, participants were adults, exercise intervention was longer than 4 weeks, no dietary intervention occurred, and the effect of the intervention on liver fat was quantified via magnetic resonance imaging/proton magnetic resonance spectroscopy. RESULTS: Of 21 597 studies retrieved, 16 were included involving 706 participants. Exercise was found to have a beneficial effect on liver fat without dietary modification (-2.4%, -3.13 to -1.66) (mean, 95% CI). Pearson correlation showed significant relationships between change in liver fat and change in weight (r = 0.67, P = .007), liver enzymes aspartate aminotransferase (r = 0.76, P = .002) and alanine aminotransferase (r = 0.91, P < .001), and cardiorespiratory fitness VO2 peak (peak volume oxygen consumption) (r = -0.88, P = .004). By multivariate regression, change in weight and change in VO2 peak significantly contributed to change in liver fat (R2 = 0.84, P = .01). CONCLUSIONS: This systematic review found that exercise without dietary intervention improves liver fat and that clinical markers may be useful proxies for quantifying liver fat changes.

Relación entre proteínas carboniladas y factor necrótico tumoral alfa con fuerza muscular en mujeres jóvenes y mayores: estudio exploratorio / Association between carbonyl proteins and tumor necrosis factor alpha with muscle strength in young and older women: exploratory study

Introducción. Actualmente se ha planteado la existencia de una estrecha relación entre el estrés oxidativo e inflamatorio crónico de bajo grado. Ambos tipos de estrés han sido relacionados con la función muscular en adultos mayores (AM), sin embargo, no se ha definido si esta relación es particular para AM. El objetivo del estudio fue determinar la relación entre los niveles plasmáticos de factor necrótico tumoral alfa (TNF-α) y proteínas carboniladas (PC) con la fuerza muscular en un grupo de mujeres jóvenes y adultas mayores. Métodos. Estudio exploratorio. En 13 mujeres mayores y 8 jóvenes, fueron valorados los niveles plasmáticos de PC y TNF-α. La fuerza muscular se valoró mediante las pruebas de fuerza prensil, fuerza isométrica máxima voluntaria de cuádriceps, el arm curl test y el pararse-sentarse en 30 segundos. Resultados. No existieron diferencias entre las concentraciones plasmáticas de PC y TNF-α entre los grupos de estudio, las cuales se relacionaron entre sí solo en el grupo de AM. Se observó una relación no lineal entre las concentraciones plasmáticas de PC y la fuerza isométrica máxima voluntaria de cuádriceps solo en el grupo de AM (R2 = 36,2; p = 0,038). Para el caso del TNF-α no se encontraron asociaciones significativas con ninguna de las pruebas aplicadas. Conclusiones. Existe relación entre las concentraciones plasmáticas de PC y la fuerza isométrica máxima voluntaria de cuádriceps solo en el grupo de AM lo que podría indicar una acción deletérea del estrés oxidativo sobre la función muscular particularmente en el envejecimiento (AU)

Introduction. It has recently been proposed that there is a close relationship between oxidative stress and low-grade chronic inflammation. Both processes have been related separately to muscle function in older adults (OA). Nevertheless, it still has not been determined if this relationship is present particularly in OA. The objective of this study was to determine the relationship between the plasma levels of TNF-α and carbonyl proteins (CP) and muscle strength in a group of young and older women. Methods. An exploratory study was conducted on 13 older and 8 young women, in whom the plasma levels of CP and TNF-α were measured. Muscle strength was measured by handgrip test, quadriceps voluntary maximal isometric strength, arm curl, and the 30 second sit to stand test. Results. There were no differences in the plasma levels of CP and TNF-α between the groups, but there was relationship between the biomarkers only in the OA group. A non-linear relationship was observed between CP and quadriceps voluntary maximal isometric strength only in the OA group (R2 = 36.2; P=.038). For TNF-α there were no significant association with any of the applied tests. Conclusions. There is an association between CP and quadriceps voluntary maximal isometric strength only in the OA group, which could indicate a deleterious action of oxidative stress on muscle function, particularly in aging (AU)

[Association between carbonyl proteins and tumor necrosis factor alpha with muscle strength in young and older women: exploratory study]. / Relación entre proteínas carboniladas y factor necrótico tumoral alfa con fuerza muscular en mujeres jóvenes y mayores: estudio exploratorio.

INTRODUCTION: It has recently been proposed that there is a close relationship between oxidative stress and low-grade chronic inflammation. Both processes have been related separately to muscle function in older adults (OA). Nevertheless, it still has not been determined if this relationship is present particularly in OA. The objective of this study was to determine the relationship between the plasma levels of TNF-α and carbonyl proteins (CP) and muscle strength in a group of young and older women. METHODS: An exploratory study was conducted on 13 older and 8 young women, in whom the plasma levels of CP and TNF-α were measured. Muscle strength was measured by handgrip test, quadriceps voluntary maximal isometric strength, arm curl, and the 30 second sit to stand test. RESULTS: There were no differences in the plasma levels of CP and TNF-α between the groups, but there was relationship between the biomarkers only in the OA group. A non-linear relationship was observed between CP and quadriceps voluntary maximal isometric strength only in the OA group (R(2)=36.2; P=.038). For TNF-α there were no significant association with any of the applied tests. CONCLUSIONS: There is an association between CP and quadriceps voluntary maximal isometric strength only in the OA group, which could indicate a deleterious action of oxidative stress on muscle function, particularly in aging.