Date Published: February 2, 2017
Publisher: Public Library of Science
Author(s): Lara Ferreira Paraiso, Ana Flávia Mayrink Gonçalves-e-Oliveira, Lucas Moreira Cunha, Omar Pereira de Almeida Neto, Adriana Garcia Pacheco, Karinne Beatriz Gonçalves Araújo, Mário da Silva Garrote-Filho, Morun Bernardino Neto, Nilson Penha-Silva, Derek Laver.
This study aimed to evaluate the influence of acute and chronic exercise on erythrocyte membrane stability and various blood indices in a population consisting of five national-level male swimmers, over 18 weeks of training. The evaluations were made at the beginning and end of the 1st, 7th, 13th and 18th weeks, when volume and training intensity have changed. The effects manifested at the beginning of those weeks were considered due to chronic adaptations, while the effects observed at the end of the weeks were considered due to acute manifestations of the exercise load of that week. Acute changes resulting from the exercise comprised increases in creatine kinase activity (CK) and leukocyte count (Leu), and decrease in hematocrit (Ht) and mean corpuscular volume (MCV), at the end of the first week; increase in the activities of CK and lactate dehydrogenase (LDH), in the uric acid (UA) concentration and Leu count, at the end of the seventh week; increases in CK and LDH activities and in the mean corpuscular hemoglobin concentration (MCHC), at the end of the 13th week; and decrease in the value of the osmotic stability index 1/H50 and increases in the CK activity and platelets (Plt) count, at the end of the 18th week. Chronic changes due to training comprised increase in the values of 1/H50, CK, LDH, high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), serum iron (Fe), MCV and Plt. Although acute training has resulted in decrease in the osmotic stability of erythrocytes, possibly associated with exacerbation of the oxidative processes during intense exercise, chronic training over 18 weeks resulted in increased osmotic stability of erythrocytes, possibly by modulation in the membrane cholesterol content by low and high density lipoproteins.
Physical exercise increases oxygen (O2) consumption by the body, mainly in the muscle tissues [1, 2]. In the case of athletes, a good oxygen uptake is extremely important for tolerance to severe exercise [3, 4]. Red blood cells (RBC) should be efficient in O2 uptake and delivery to meet the high demand of tissues . The structure of the membranes of these cells plays an important role in maintaining its functionality; an imbalance in the physicochemical properties of the membrane can make the cell to become dysfunctional, hindering tissue oxygenation [6, 7].
Fig 1 shows a typical curve of dependency of the amount of released hemoglobin, given the absorbance at 540 nm, in function of the NaCl concentration in the medium.
The major finding of our research was that the training, both acute and chronic, has affected the osmotic stability of erythrocytes, as well as the values of various other parameters studied here. The body of the athletes was affected in some way in every training session, even in the first training, which was a light training, in which neither the intensity nor the volume of exercise were high.