Efeitos da exposição controlada a agentes estressores sobre os marcadores bioquímicos de militares do Exército Brasileiro durante curso de alta intensidade

Abstract

The Activity of Controlled Exposure to Stressors (AECAE), associated with physiological wear promoted by the continued training of troops of the Brazilian Army (EB), may contribute to the development of rhabdomyolysis by strenuous exercise or effort rhabdomyolysis (ER). Characterized by the rupture of the membrane of skeletal muscle cells, ER leads to increased serum levels of intracellular proteins and renal overload, with symptoms that include muscle fatigue, weakness and brown urine. These symptoms can be obscured by exhaustion of training, resulting in irreparable kidney damage or even death. The present study aimed to evaluate the effects of AECAE on serum biochemical markers and the incidence of ER, in order to identify biochemical predictors that may indicate susceptibility to the development of ER among subjects submitted to AECAE. We also sought to evaluate the AECAE impact on the physical and biochemical health of individuals, by measuring various serum biomarkers at different times in AECAE. Of these, 49 soldiers were submitted to AECAE (case group) and 61 soldiers were not submitted to AECAE (control group). All protocols were approved by the UFG’s Research Ethics Committee (Opinion No. 6.287.272/UFG). Serum levels of 23 biochemical markers were measured during four moments evaluated in the study: basal (7 days before the beginning of AECAE; C1); minimum AECAE (exposure onset; C2); maximum AECAE (peak exposure; C3) and recovery (48 hours after the end of AECAE Maximum; C4). AECAE was designed to train participants under situations of physical, psychological, water and nutritional stress in a controlled manner. The protocol sought to simulate extreme conditions within a monitored environment to ensure the safety of those involved and the integrity of the data collected. All laboratory information was made available through an anonymized database. To determine the liver and kidney function, the ratios between AST (aspartate aminotransferase) and ALT (alanine aminotransferase) and between urea and creatinine were calculated, respectively. The serum creatine phosphokinase (CK) concentration > 1000U/L was used as a criterion for defining ER. During the peak AECAE, increased serum levels of CK, Lactic Dehydrogenase (LDH), AST, alanine aminotransferase (ALT), Creatine Phosphokinase Miocárdica (CK-MB), uric acid, total and direct bilirubin, creatinine, urea, urea/creatinine ratio, high density lipoprotein (HDL), phosphorus (P+), magnesium (Mg+) and total calcium (Ca2+). These values were also significantly higher than those observed in the control group. In addition, 48 hours after the end of maximum exposure, it was observed that the levels of LDH, CK, CK-MB, AST, ALT and Urea/Creatinine ratio were still elevated in subjects submitted to AECAE. In addition, based on the increase of the muscle degradation marker (CK>1000), it was found that 6% of the individuals in the group developed risk of ER in the minimum AECAE and 51% in the maximum AECAE. In relation to the risk predictors, we identified that individuals from the experimental group with basal values of urea/creatinine 28 ratio have 3.6 times more chances of developing ER during high intensity exercise (OR = 3.64 [1.11-11.97]; p = 0.03). The analysis of possible biochemical markers to determine susceptibility to success or failure in stressful situations, showed that individuals with higher baseline concentrations of direct bilirubin and CK and lower plasma levels of urea, CK-MB and LDH have a greater predisposition to success before exposure to high intensity physical and psychological stressors. The results of this study demonstrate that AECAE causes significant changes in several serum biochemical markers, which are indicative of muscle stress and organ dysfunction. Notably, even 48 hours after the end of AECAE, many of these markers have not yet returned to their baseline values, suggesting that this period may not be adequate to ensure complete muscle and renal recovery. In addition, the basal level of urea/creatinine ratio 28 has the potential to be used as a predictor of susceptibility to ER development during AECAE, allowing the selection of subjects and risk mitigation of developing this condition, that should be better investigated in future studies. Finally, the basal biochemical profile of direct bilirubin, CK, urea, CK-MB and LDH can serve as a promising indicator of greater resilience and success in high intensity stressful situations.