Blood flow and pressure relationships which determine vo2max

William F. Brechue, Bill T. Ameredes, Jack K. Barclay, Wendell N. Stainsby

Research output: Contribution to journalArticle

19 Scopus citations

Abstract

Blood flow and pressure relationships which determine VO2max. Med. Sci. Sports Exerc., Vol. 27, No. 1, pp. 37-42, 1995. The role of O2 delivery in regulating VO2max has been studied in an isolated gastrocnemius-plantaris muscle preparation contracting insitu; recent data addressing this issue are presented. VO2 increases nonlinearly with stimulation frequency reaching a peak at 5 twitches·s−1 or 1 tet·S−1 (200 ms trains, 50 imp·s−1). Further increases in stimulation frequency result in a lower VO2. Measured VO2 maxima are less than predicted VO2 capacity, and peak VO2 during tetanic contractions is greater than that during twitches. Above 150 imp·min−1, VO2 is directly related to the level of blood flow attained as VO2/Q (arterial-venous O2 difference) is fixed by some unknown mechanism. Increasing blood flow, with a pump, during 1·s−1 tetanic contractions increases O2 diffusive conductance and peak VO2. When O2 delivery is reduced, ischemic hypoxia appears to result in more rapid reductions in muscle performance than hypoxic hypoxia because of decreases in perfusion pressure and Q.31P-NMR studies reveal that reductions in creatine phosphate and energy charge are similar between ischemia and hypoxia suggesting a common regulator, O2. We conclude that VO2max is limited by O2 delivery as a result of a limited and uneven distribution of muscle blood flow. These limitations appear secondary to mechanical restraints imposed by contraction duty cycle and vascular compression.

Original languageEnglish (US)
Pages (from-to)37-42
Number of pages6
JournalMedicine and Science in Sports and Exercise
Volume27
Issue number1
DOIs
StatePublished - Jan 1995
Externally publishedYes

Keywords

  • Blood flow distribution
  • Contractions
  • Hyperemia
  • Hypoxic hypoxia
  • Ischemic hypoxia
  • Perfusion pressure
  • Skeletal muscle
  • Vascular compression

ASJC Scopus subject areas

  • Orthopedics and Sports Medicine
  • Physical Therapy, Sports Therapy and Rehabilitation

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