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Study of plasma redox biomarkers for accurate stress evaluation in athletes
  1. M Paes de Barros1,
  2. C O Soares2,
  3. B Pereira3,
  4. E J H Bechara2,
  5. L R Silveira3,
  6. R Curi4,
  7. T P Souza-Junior5
  1. 1Institute of Physical Activity and Sports Sciences (ICAFE), Universidade Cruzeiro do Sul, Sao Paulo, Brazil
  2. 2Department of Biochemistry, Universidade de Sao Paulo, Sao Paulo, Brazil
  3. 3School of Physical Education and Sports, Universidade de Sao Paulo, Sao Paulo, Brazil
  4. 4Department of Physiology and Biophysics (ICB1), Universidade de Sao Paulo, Sao Paulo, Brazil
  5. 5Department of Physical Education, Universidade Federal do Parana, Curitiba, Brazil

Abstract

Background A plethora of data revealed that reactive oxygen species (ROS) are normally produced during/after endurance or resistance exercise. Drastic drops in performance, precocious fatigue and injury risk are putative outcomes of the ROS-mediated biochemical changes. On the other hand, adequate ROS production is essential to provide the desired physiological adaptations of training and to avoid related immune depression.

Objective This work aims to test plasma biomarkers of oxidative stress for an accurate evaluation of exhaustion in athletes.

Design Subjects were prospectively randomised evaluated.

Setting Male cyclists of Brazilian college league (university games) were selected.

Participants Subjects (n=20) had no history of smoking, alcohol abuse, or systemic disease.

Interventions A Wingate Test was carried out using a Cybex cycle ergometer with increasing loads up to 10% BW (preheat procedure for 5 min). Athletes were strongly encouraged during the test for maximum effort achievement.

Main outcome measurements Blood samples (5 ml) were collected before and after the Wingate test, using EDTA-containing Vaccuntainer kits. Total iron, haemoglobin, uric acid, Ferric-reducing activity (FRAP), and malondialdehyde (biomarker of lipid oxidation) were measured in plasma.

Results Plasma iron and FRAP levels varied consistently when total amounts released from time zero to 60 min after the Wingate test were evaluated (R=0.939). Remarkably, uric acid was identified as one of the major contributors for FRAP capacity, thus, restricting iron ions participation as catalysts for ROS overproduction during exercise. Lower indexes of lipid oxidation were reported under these circumstances.

Conclusion The pool of plasma biomarkers – total iron, FRAP, uric acid and malondialdehyde – are good candidates for an efficient evaluation of oxidative stress related to exhaustion. Further investigations are necessary to precise how responsive those parameters are at different exercise intensities.

Financial support: FAPESP, CAPES & CNPq (Brazil); BioReal AB/Fuji Health Sciences (Sweden/Japan).

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