Diferentes níveis de desidratação e seu impacto na amonemia e desempenho cognitivo-motor no calor

Abstract

Purpose: Influences of dehydration on ammonemia and cerebral disorders during exercise in the heat are unclear. Therefore the aim of this study is investigate different dehydration levels and its impact on blood ammonia and cognitive-motor performance in the heat. Methods: sixteen runners performed an half marathon race (21 km) and in the end they were divided in two groups: body mass change percentual (Δ% BM) less than 1% (G1%) and Δ % BM greater than 3% (G3%). Before and after the race participants underwent blood collections and analyses, assessments of cognitive-motor and hydration status, the environmental thermal stress and changes in body temperature were also evaluated. Results: The Δ% BM was greater in G3% (-3,85 ± 0,28) than G1% (-0,40 ± 0,53) (P <0,001). The equivalent of rectal temperature increased only in G3% (P = 0,037). Increased in G1% and G3% ammonia (P < 0,001; P = 0,002), urea (P = 0,046; P = 0,011) and lactate (P = 0,007; P = 0,004). Also increased in G1% and G3% the enzymes aspartate aminotransferase (AST) (P = 0,002; P = 0,027), alanine aminotransferase (ALT) (P = 0,040; P = 0,006), creatine kinase (CK) (P = 0,039; P = 0,010) and lactate dehydrogenase (LDH) (P = 0,002; P = 0,038). Only LDH was greater in G3% than G1% (P = 0,010). The cognitive-motor performance did not present difference between the groups. Conclusion: The exercise in the heat, with dehydration up to ~ 4% of Δ% BM, exacerbates the ammonemia similarly to lower levels of dehydration, without impairment in cognitive-motor performance.