Influence of hydrostatic pressure gradients on regulation of plasma volume after exercise

Gary W. Mack*, Roger Yang, Alan R. Hargens, Kei Nagashima, Andrew Haskell

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

32 Citations (Scopus)


The impact of posture on the immediate recovery of intravascular fluid and protein after intense exercise was determined in 14 volunteers. Forces which govern fluid and protein movement in muscle interstitial fluid pressure (P(ISF)), interstitial colloid osmotic pressure (COP(i)), and plasma colloid osmotic pressure (COP(p)) were measured before and after exercise in the supine or upright position. During exercise, plasma volume (PV) decreased by 5.7 ± 0.7 and 7.0 ± 0.5 ml/kg body weight in the supine and upright posture, respectively. During recovery, PV returned to its baseline value within 30 min regardless of posture. PV fell below this level by 60 and 120 min in the supine and upright posture, respectively (P < 0.05). Maintenance of PV in the upright position was associated with a decrease in systolic blood pressure, and increase in COP(p) (from 25 ± 1 to 27 ± 1 mmHg; P < 0.05), and an increase in P(ISF) (from 5 ± 1 to 6 ± 2 mmHg), whereas COP(i) was unchanged. Increased P(ISF) indicates that the hydrostatic pressure gradient favors fluid movement into the vascular space. However, retention of the recaptured fluid in the plasma is promoted only in the upright posture because of increased COP(p).

Original languageEnglish
Pages (from-to)667-675
Number of pages9
JournalJournal of Applied Physiology
Issue number2
Publication statusPublished - 1998 Aug
Externally publishedYes


  • Capillary exchange
  • Colliod osmotic pressure
  • Fluid shift

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)


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