ABSTRACT
BACKGROUND: Inflammatory cytokines and acute phase proteins increase with aging, promoting a chronic low-grade inflammation. Studies have shown a positive effect of exercise on inflammatory markers in older persons. Interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), and C-reactive protein (CRP) are the main biomarkers investigated. However, it is unclear if exercise could decrease all these biomarkers. PURPOSE: The aim was to analyze the effect of chronic exercise on IL-6, TNF-α, and CRP levels in older persons. METHODS: Preferred Reporting Items in Systematic Reviews and Meta-analyses guidelines were adopted. Original articles that investigated the effect of chronic exercise on inflammatory profile of the elderly persons were eligible for this review. The databases PubMed, PEDro, EBSCO, and BioMed Central were searched. Three reviewers evaluated each publication for reducing bias. Data about IL-6, TNF-α, and CRP were collected and analyzed. A standardized mean difference based on estimated pooled effect size was calculated considering heterogeneity index (I2) and random effect. RESULTS: Seventy-six studies were retrieved from databases, and 8 of them were analyzed. IL-6 and CRP levels decreased after chronic exercise (overall effect P < .05). CONCLUSION: Regular exercise decreases IL-6 and CRP levels in older persons. The effect of exercise on TNF-α remains unclear.
Subject(s)
C-Reactive Protein/metabolism , Exercise/physiology , Inflammation/physiopathology , Interleukin-6/blood , Tumor Necrosis Factor-alpha/blood , Aged , Biomarkers/blood , Female , HumansABSTRACT
Several indicators have been used to analyze scientific journals, with the impact factor and the number of citations in a 2-yr calendar time frame (2-YRC) being the most common factors. However, considering that the Journal of Applied Physiology (JAPPL) appears monthly and that calculations of these indicators are based on citations of papers published in previous years, we hypothesized that articles published at the beginning of the year would be cited more in the 2-YRC compared with those appearing in the last issues of the year, a phenomena known as a relative age effect. Our objective was to confirm the existence of a relative age effect in the 2-YRC for original articles published in JAPPL. From 2005 to 2008, a total of 1,726 original articles were published, according to the Web of Science, and 9,973 citations in 2-YRC, varying from 0 to 45, with a mean of 5.78 for individual papers. Although there were no differences in the number of original articles published in a given month (P = 0.99), the 2-YRC varied considerably throughout the year, being higher for those earlier issues of the year, as shown by the linear regression analysis (r(2) = 0.76; P < 0.001). The 2-YRC began at 6.62 during the first 3 mo of the year, dropping by 10% at each 3-mo period. In summary, the longer an article has been out there, the more citations it collects. The relative age effect is a potential confounding variable for the assessment and interpretation of 2-YRC (using calendar years) from JAPPL original articles.
