The Effect of Passive Dehydration on Postural Sway In Healthy Adult Males: 837

Marjorie Wilson, Alison Lawther

    Research output: Contribution to journalArticle

    Abstract

    Purpose: Falls are implicated in 19-30% of accidents in fire fighters and miners, with loss of postural control as a possible causal factor. Both occupations can involve extremes of heat. Inadequate fluid intake can lead to hypohydration. Previous studies have looked at fatiguing activity to induce hypohydration. The purpose of this study was 1) to determine if passive hypohydration has a substantial effect on static postural stability in healthy adult males and 2) to determine if urine specific gravity (Usg) correlates with postural stability.
    Method: 12 healthy adult males (Mean ± SD, Age 22 ± 0.7 yrs, height 175.7 ± 9.4 cm, mass 77.0 ± 8.8 kg) consented to take part. Subjects were tested on two occasions separated by 7 days. Baseline measures were determined: nude body mass; the range of medial-lateral (ML) and anterior-posterior (AP) Centre of Pressure (COP) with eyes open and eyes closed using a Kistler Force platform; (Usg) using a digital refractometer. On the first visit (Dehydration, DE), subjects were passively dehydrated to 3% Body Mass Loss (BML) in an environmental chamber (40°C, 70% relative humidity). The Usg and COP readings were recorded at 3% BML. On the second visit (Control, CON) subjects were exposed to the same environmental conditions but consumed volumes of water equivalent to those lost in sweat in the initial DE trial to maintain body weight. The Usg and COP readings were taken at the same time-points for each subject as during initial DE trial.
    Results: The mean difference in ML postural stability between the DE and CON conditions was -8.61 mm (90% CI, -5.05 to -12.17 mm). The mean difference in AP postural stability between the DE and CON conditions was -7.57 mm (90% CI, -4.31 to -10.83 mm). The mean difference in ML postural stability between eyes open and eyes closed was -1.18 mm (90% CI, 3.57 to -5.92 mm). The mean difference in AP postural stability between the eyes open and eyes closed was -3.50 mm (90% CI, -0.25 to -7.24 mm). No substantial correlations were observed between Usg and ML or AP COP ranges.
    Conclusion: Passive dehydration of 3% BML has a small effect on ML and AP postural stability COP range. Stability appeared to be better for the DE trial (hypohydrated subjects) relative to the CON trial (euhydrated subjects). The Usg does not correlate substantially with COP range measures of postural stability.
    Original languageEnglish
    Pages (from-to)S75
    JournalMedicine & Science in Sports & Exercise
    Volume40
    Issue numberSupplement
    DOIs
    Publication statusPublished - 1 May 2008

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