Effects of heat stress and dehydration on cognitive function in elite female field hockey players

Abstract

Background: It has previously been suggested that heat exposure and hypohydration have negative effects on cognitive performance, which may impact upon sporting performance. The aim of the present study was to examine the independent effects of heat stress and hypohydration on cognitive performance in elite female field hockey players.

Methods: Eight unacclimatised elite field hockey players (age: 22 ± 3 y; height: 1.68 ± 0.05 m; body mass: 63.1 ± 6.0 kg) completed a cognitive test battery before and after 50 min of field hockey specific exercise on a treadmill in four experimental trials; two in hot conditions (33.3 ± 0.1 °C), and two in moderate (16.0 ± 3.0 °C), both with and without ad libitum water intake.

Results: On the visual search test, participants were faster overall in the heat (1941 vs. 2104 ms, p = 0.001). Response times were quicker in the heat on the Sternberg paradigm (463 vs. 473 ms, p = 0.024) and accuracy was improved (by 1.9%, p = 0.004). There was no effect of hydration status on any of the markers of cognitive function.

Conclusions: Overall, the findings suggest that in elite field hockey players exposure to heat enhances response times and/or accuracy on a battery of cognitive function tests. However, hypohydration does not appear to affect cognitive performance in elite field hockey players.

Keywords: Cognitive performance; Decision-making; Hypohydration; Intermittent exercise; Skill; Team sports.

Fig. 1

The 1^st half and 2^nd half heart rate data (mean ± SD) observed during the FHITP. (HF: hot environment with fluid; HNF; hot environment no fluid; MF; moderate environment with fluid; MNF: moderate environment no fluid). Main effect condition (P = 0.001), hydration state (P = 0.020), time (P = 0.001) and condition x time interaction (P = 0.005). a = P < 0.05 between HF and MF, d = P < 0.05 between HNF and MF

Fig. 2

The mean (± SD) rectal temperature observed during the FHITP. (HF: hot environment with fluid; HNF; hot environment no fluid; MF; moderate environment with fluid; MNF: moderate environment no fluid). For clarity SD is not shown. SD for HF = ± 0.4; HNF = ± 0.4; MF = ± 0.4; MNF = ± 0.3. Main effect condition (P = 0.029), time (P < 0.001) and condition x time interaction (P < 0.001). a = P < 0.05 between HF and MF, d = P < 0.05 between HNF and MF, e = P < 0.05 between MF and MNF

Fig. 3

The mean (± SD) rating of perceived exertion (panel a), thermal sensation rating (panel b) and thirst sensation (panel c) observed during the FHITP. (HF: hot environment with fluid; HNF; hot environment no fluid; MF; moderate environment with fluid; MNF: moderate environment no fluid). RPE: Main effect condition (P < 0.001), fluid (P = 0.003), time (P < 0.001) and condition x time interaction (P < 0.001) and fluid x time interaction (P = 0.002). Thermal sensation: Main effect condition (P < 0.001), time (P < 0.001) and condition x time interaction (P < 0.001). Thirst sensation: Main effect fluid (P < 0.001), time (P < 0.001) and fluid x time interaction (P < 0.001) and condition x fluid x time interaction (P = 0.018). a = P < 0.05 between HF and MF, b = P < 0.05 between HF and MNF, c = P < 0.05 between HNF and MNF, d = P < 0.05 between HNF and MF, e = P < 0.05 between MF and MNF, f = P < 0.05 between HF and HNF

Fig. 4

The mean (± SD) blood lactate (panel a) and glucose (panel b) concentration during the FHITP. (HF: hot environment with fluid; HNF; hot environment no fluid; MF; moderate environment with fluid; MNF: moderate environment no fluid). Lactate: Main effect condition (P = 0.040), time (P < 0.001) and condition x time interaction (P < 0.001). Glucose: Main effect condition (P = 0.025), time (P < 0.001) and condition x time interaction (P < 0.001). a = P < 0.05 between HF and MF, b = P < 0.05 between HF and MNF, c = P < 0.05 between HNF and MNF, d = P < 0.05 between HNF and MF