Dear editor
We read with interest the article by Kortas et al1 entitled “Effect of Nordic Walking training on iron metabolism in elderly women.” In their study, the authors investigated the effect of Nordic Walking (NW) training on serum ferritin, C-reactive protein (CRP), hepcidin, hemojuvelin, and vitamin D, which have been stated as components of the inflammatory system. In this study, while NW training significantly reduced iron stores and increased hemojuvelin and tended to reduce CRP levels, it did not affect hepcidin levels. The authors also observed a significant weight loss after training. The authors concluded NW training has pro-healthy effects manifested by decreased inflammation and a drop in iron stores.
It is well known that obesity is associated with insulin resistance and physical exercise and weight loss reduce insulin resistance. Several studies indicate a positive correlation between iron levels and insulin resistance.2,3 There is also a relationship between insulin resistance and CRP levels.4 The possibility of decreased insulin resistance with weight loss after training can also contribute to the decline in CRP and ferritin levels in this study. The authors mentioned that they did not observe the anticipated increase in hepcidin levels after exercise. As the authors stated, hepcidin levels increase in response to both inflammation and exercise. Because the mean body mass index of the study population is in the overweight range, these subjects might have insulin resistance and associated inflammation. Thus, the anticipated increase in hepcidin levels with exercise might have been attenuated via decreased inflammation in this study. This two-way interaction may account for the unchanged hepcidin levels. The authors did not report insulin levels in this study and did not discuss the probable effect of insulin resistance on the relationship between ferritin and exercise. We suggest that consideration of these factors may facilitate interpretation of the findings of this study. We also suggest that insulin resistance would better be assessed in future studies in this field.
Footnotes
Disclosure
The authors report no conflict of interest in this communication.
References
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