Effects of 8 days acclimation on biological and performance response in a tropical climate

This study was designed to determine the acclimation process elicited by exposure to a tropical climate.

Nine triathletes performed 3 outdoor indirect continuous running multistage tests in both thermoneutral and tropical conditions. Before travelling to the tropical area (Martinique Island, FWI), the triathletes performed the thermoneutral test (TN) in 14 degrees C and 45% rh conditions. The tropical tests were performed 2 and 8 days after arrival (T2 and T8, performed at a mean environmental temperature of 33.4 degrees C and 75.5% rh). The day before T8, blood samples were drawn for biochemical analysis. During each test, tympanic temperature, sweat rate, weight loss, heart rate (HR), and performance were recorded.

The results demonstrated that: 1) the mean tympanic temperature was greater in T2 (p<0.001) and T8 (p<0.01) than in TN; 2) the mean sweat rate was significantly greater (p<0.001) in T2 and T8 than in TN and significantly greater in T8 than in T2 (p<0.03); 3) the weight loss after trials was significantly greater (p<0.001) in T2 and T8 than in TN and in T8 than in T2 (p<0.04); 4) the mean HR and the HR at rest were significantly greater in T2 than in TN (p<0.001) and T8 (p<0.005); 6) significant reductions were observed in T8 vs TN in red cell count (p<0.05) and plasma proteins (p<0.04), the consequence of a 7.5% plasma volume expansion; and 7) the performance was significantly lower in both T2 (p<0.02) and T8 (p<0.03) than in TN.

We concluded that 8 days exposure to hot/wet conditions induced impairments in physiological responses and performance that were still evident on the 8th day. Further and longer outdoor studies are needed to investigate if return to optimal performance levels after adaptation to hot/wet conditions is possible.