Skip Navigation LinksHome > October 2006 - Volume 38 - Issue 10 > No Effect of 5% Hypohydration on Running Economy of Competit...
Medicine & Science in Sports & Exercise:
doi: 10.1249/01.mss.0000230123.68394.ff
BASIC SCIENCES: Original Investigations

No Effect of 5% Hypohydration on Running Economy of Competitive Runners at 23°C

ARMSTRONG, LAWRENCE E.1; WHITTLESEY, MICHAEL J.2; CASA, DOUGLAS J.1; ELLIOTT, TABATHA A.1; KAVOURAS, STAVROS A.3; KEITH, NICOLE R.4; MARESH, CARL M.1

Collapse Box

Abstract

Purpose: Although running economy (RE) is recognized as an integral component of successful endurance performance and is affected by numerous factors, little is known about the influence of body water loss on RE. This investigation examined the effects of hypohydration (HY) on RE and associated physiological responses.

Methods: Ten highly trained collegiate distance runners (mean ± SD; age, 20 ± 3 yr; height, 178.5 ± 6.3 cm; body mass, 66.7 ± 5.4 kg; V˙O2max, 66.5 ± 4.1 mL·kg−1·min−1) participated in four experiments on separate days, twice in a euhydrated (EU) and twice in a HY state (−5.5 and −5.7% body mass loss achieved during 24 h). At each hydration level, subjects performed one 10-min treadmill run per day (23°C environment), at either 70% V˙O2max (EU 70% or HY 70%) or 85% V˙O2max (EU 85% or HY 85%) in a randomized, repeated-measures design. Cardiopulmonary, metabolic, thermal, hormonal, and perceptual variables were measured.

Results: No between-treatment differences existed for RE (EU 70%, 46.3 ± 3.2; HY 70%, 47.2 ± 3.8; EU 85%, 58.6 ± 2.8; HY 85%, 58.9 ± 4.1 mL·kg−1·min−1), postexercise plasma lactate concentration (EU 70%, 1.9 ± 0.6; HY 70%, 1.8 ± 0.6; EU 85%, 6.5 ± 3.5; HY 85%, 6.4 ± 3.5 mmol·L−1), or rating of perceived exertion. HY resulted in a greater (P < 0.05 to 0.001) heart rate (HR), rectal temperature, and plasma norepinephrine concentration (NE), concurrent with reduced cardiac output, stroke volume, and respiratory exchange ratio.

Conclusion: HY did not alter the RE or lactate accumulation of endurance athletes during 10 min of exercise at 70 and 85% V˙O2max. These findings indicate that HY had no effect on RE, but that it increased physiological strain in a 23°C environment.

©2006The American College of Sports Medicine

Login

Article Tools

Share

Search for Similar Articles
You may search for similar articles that contain these same keywords or you may modify the keyword list to augment your search.

Connect With Us