title: The effect of cold water endurance swimming on core temperature in aspiring English Channel swimmers.
abstract: BACKGROUND
  The purpose of this study was to determine if cold water swimmers (CWS) developed hypothermia over a 6-h cold water endurance swim and whether body composition, stroke rate (SR) or personal characteristics correlated with core temperature (TC) change. Nine experienced male and female CWS who were aspiring English Channel (EC) swimmers volunteered to participate. Subjects aimed to complete their 6-h EC qualifying swim (water 15-15.8 °C/air 15-25 °C) while researchers intermittently monitored TC and SR. Data obtained included anthropometry (height, mass, segmental body composition), training volume and EC completion.
  
  
  RESULTS
  Of the nine swimmers who volunteered, all successfully completed their EC qualifying swim. Six CWS had complete data included in analysis. One CWS demonstrated hypothermia (34.8 °C) at 6-h. TC rate of decline was slower in the first 3 h (-0.06 °C/hr) compared to the last 3 h (-0.36 °C/hr) of the swim. Older age was significantly correlated to TC change (r = -0.901, p < 0.05) and SR change (r = -0.915, p < 0.05). Absolute and percentage body fat (BF) were not significantly associated with higher TC. Mean SR over the 6-h swim was 57.8 spm (range 48-73 spm), and a significant (p < 0.05) decline in SR was observed over the 6 h (-9.7 %). A strong, positive correlation was found between SR change between 3 and 6 h and TC over the 6 h (r = 0.840, p < 0.05) and TC from 3-6 h (r = 0.827, p < 0.05). Seven of the nine participants (77.8 %) in this study successfully completed the EC crossing. Successful EC swimmers swam in the pool and open water (OW); however, they swam significantly [t (7) = -2.433, p < 0.05] more kilometres (M = 19.09 km/wk ± 5.55) in OW than unsuccessful (M = 9 km/wk ± 1.41) EC swimmers. There was a significant relationship between EC crossing time and height (r = -0.817, p < 0.05), but no other variables and EC crossing time.
  
  
  CONCLUSIONS
  Cold water endurance swim (CWES) of 6-h duration at 15-16 °C resulted in TC reduction in the majority of swimmers regardless of anthropometry. More research is required to determine why some CWS are able to maintain their TC throughout a CWES. Our results indicate that older swimmers are at greater risk of developing hypothermia, and that SR decline is an indicator of TC decline. Our results also suggest that OW swimming training combined with pool training is important for EC swim success.
authors.affiliation: Nutrition and Dietetics, Institute of Health and Sport, Faculty of Health Sciences, Bond University, Gold Coast, QLD Australia.
authors.forename: Tara
authors.identifier: 0000-0002-8048-2585
authors.initials: T
authors.lastname: Diversi
authors.affiliation: Nutrition and Dietetics, Institute of Health and Sport, Faculty of Health Sciences, Bond University, Gold Coast, QLD Australia.
authors.forename: Vanessa
authors.initials: V
authors.lastname: Franks-Kardum
authors.affiliation: Water Based Research Unit, Bond University, Gold Coast, QLD Australia ; Exercise Health and Performance Faculty Research Group, Faculty of Health Sciences, The University of Sydney, Lidcombe, Sydney, NSW Australia.
authors.forename: Mike
authors.initials: M
authors.lastname: Climstein
keywords: Body composition; Body fat; Cold water swimming; Core temperature; Dual-energy x-ray absorptiometry; English Channel; Hypothermia; Open water swimming
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