Alterations in acid-base-balance are accompanied by changes in blood osmolality. In vitro, in oxygenated blood the following relationship was found: Δosm = -31.7 × ΔpH. During physical activity (cycle-ergometer, workload beginning with 50 watt, increasing in steps of 50 watt every 3 min; n = 10) the in vivo relationship is Δosm = -136.6 × ΔpH + 1.9. A pH decrease of 0.2 units results in an increase in osmolality of 29.2 mosmol/kg H2O. Only 6.3 mosmol are due to acid-base-balance changes because the rise in lactic acid concentration is compensated for by the elimination of bicarbonate. The remaining increase of 22.7 mosmol/kg H2O is caused to a large extent by a water shift into the working muscles due to osmotic effects related to the anaerobic metabolism (ΔOsm = 2.05 × Δ[Lac] + 2.7). More than 50% of the exercise hemoconcentration can be explained by these osmotic effects. The same mechanism seems to play an important role during the early stage of hemorrhagic shock.

Exercise-Induced Hemoconcentration and Osmolality


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. 1.
    Beaumont W von (1973) Red cell volume with changes in plasma osmolality during maximal exercise. J Appl Physiol 35:47–50PubMedGoogle Scholar
  2. 2.
    Bergström J, Guarnieri G, Hultmann E (1971) Carbohydrate metabolism and electrolyte changes in human muscle tissue during heavy work. J Appl Physiol 30:122–125PubMedGoogle Scholar
  3. 3.
    Böning D, Maassen N (1983) Blood osmolality in vitro: dependence on PCO2, lactic acid concentration, and O2 saturation. J Appl Physiol 54:118–122PubMedCrossRefGoogle Scholar
  4. 4.
    Harris R, Sahlin K, Hultraann E (1977) Phosphagen and lactate contents of ra. quadriceps femoris of man after exercise. J Appl Physiol 43:852–857PubMedGoogle Scholar
  5. 5.
    Hultmann E, Sahlin K (1980) Acid base balance during exercise. Exerc Sport Sci Rev 8:41–128Google Scholar
  6. 6.
    Jacobs I, Kaiser P (1982) Lactate in blood, mixed skeletal muscle, and FT or ST fibres during cycle exercise in man. Acta Physiol Scand 114:461–466PubMedCrossRefGoogle Scholar
  7. 7.
    Lundvall J (1972) Tissue hyperosmolality as a mediator of vasodilatation and transcapillary fluid in exercising skeletal muscle. Acta Physiol Scand [Suppl] 379:1–137Google Scholar
  8. 8.
    Schnitzer W, Hinneberg H, Gebert G, Rieckert H (1978) Versuche zur Anwendung der Plethysmographie als ein indirektes Verfahren zur Beurteilung des lokalen anaeroben Muskelstoffwechsels. Dtsch Z Sportmed 29:62–66Google Scholar
  9. 9.
    Schnitzer W,Kämmereit A, Klatt J, Piechowiak H, Rieckert H (1978) Osmotische Aktivität des Blutes und Blutvolumenänderungen in der ergometrischen Leistungsdiagnostik. Dtsch Z Sportmed 29:151–158Google Scholar
  10. 10.
    Senay LC, Rogers G, Jooste P (1980) Changes in blood plasma during progressive treadmill and cycle exercise. J Appl Physiol 49:59–65PubMedGoogle Scholar
  11. 11.
    Tibes U, Hemmer B, Böning D, Schweigart U (1976) Relationships of femoral venous [k+],[H+], PO2, osmolality and orthophosphate with heartrate, ventilation, and leg blood flow during bicycle exercise in athletes and non-athletes. Europ J Appl Physiol 35:201–214CrossRefGoogle Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 1984

Authors and Affiliations

  • N. Maassen
  • D. Böning

There are no affiliations available

Personalised recommendations