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Clin J Sport Med. 2008 Mar;18(2):155-8. doi: 10.1097/JSM.0b013e31815cdd37.

Athletic performance and serial weight changes during 12- and 24-hour ultra-marathons.

Author information

1
Section of Emergency Medicine, National Yang-Ming University, Taipei, Taiwan. wfkao@vghtpe.gov.tw

Abstract

OBJECTIVE:

The principal objective of this study was to evaluate serial weight changes in athletes during 12- and 24-hour ultra-marathons and to correlate these changes with athletic performance, namely the distance covered.

DESIGN:

This was a prospective study.

SETTING:

The 2003 Soochow University international ultra-marathon.

PARTICIPANTS:

Fifty-two race participants.

INTERVENTIONS:

12- or 24-hour ultra-marathon.

MAIN OUTCOME MEASUREMENTS:

Body weight changes were measured before, at 4-hour intervals during, and immediately after the 12- and 24-hour races.

RESULTS:

Significant overall decreases in body weight were apparent at the conclusion of both races. The mean relative body weight change after the 12-hour race was -2.89 +/- 1.56%, ranging from 0 to 6.5%. The mean relative body weight change after the 24-hour race was -5.05 +/- 2.28%, ranging from -0.77% to -11.40%. Of runners in the 24-hour race, 26% lost greater than 7% of baseline body weight during the race. During both the 12- and 24-hour races, the greatest weight change (decrease) occurred during the first 4 hours. Weight remained relatively stable after 8 hours, although a further decrease was apparent between 16 and 20 hours in the 24-hour participants. Weight change had no bearing on performance in the 12-hour race, whereas weight loss was positively associated with performance in the 24-hour race.

CONCLUSIONS:

Our findings demonstrate that the majority of weight decrease/dehydration in both the 12- and 24-hour races occurred during the first 8 hours. Hence, to maintain body weight, fluid intake should be optimized in the first 8 hours for both 12- and 24-hour runners and in 16 to 20 hours for 24-hour marathon runners.

PMID:
18332691
DOI:
10.1097/JSM.0b013e31815cdd37
[Indexed for MEDLINE]

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