ISSN:
1439-6327
Keywords:
Marathon running
;
Body temperature
;
Plasma volume
;
Blood pressure
;
Plasma glucose
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Summary Twenty-one experienced runners were studied before, during and immediately after a marathon race to ascertain whether either depletion of energy substrate or rise in body temperature, or both, contribute to laterace slowing of running pace. Seven runners drank a glucose/electrolyte (GE) solution ad libitum (Na− 21 mmol 1−1, K+ 2.5 mmol l−1, Cl− 17 mmol l − l, PO4 2− 6 mmol 1−1, glucose 28 mmol 1−1) throughout the race; 6 drank water and 8 drank the GE solution diluted 1:1 with water. Although average running speeds for the three groups were not significantly different during the first two-thirds (29 km) of the race, rectal temperature was significantly higher (P 〈 0.05) and reduction of plasma volume was greater (P 〈0.05) in runners who replaced sweat losses with water. During the last one-third of the race, the average running pace of the water-replacement group slowed by 37.2%; the pace slowed by 27.9% in the 8 runners who replaced their sweat loss with GE diluted 1:1 with water (1/2 GE) and 18.2% in runners who replaced fluid loss with full-strength solution (GE). Eleven runners (5 in the water group, 4 in the 1/2 GE group and 2 in the GE group) lapsed into a walk/run/walk pace during the last 6 miles of the race. Ten of these had a rectal temperature of 39° C or greater after 29 km of running, and plasma volume in these runners was reduced by more than 10%. Only 1 runner among those who ran steadily throughout the race had such an elevation of temperature and reduction of plasma volume. A significant reduction in plasma glucose concentration (less than 3.3 mmol 1−1) was present in 5 of the 11 walk/run/walk subjects and in none of those who ran steadily. The results are consistent with the suggestion that assumption of the walk/run/walk pace resulted from high body temperature associated with either diminished plasma volume or low blood sugar.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00602353
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