Vo2max what does it really mean

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Vo2max what does it really mean

  1. 1. VO2max: what does it really mean? Andrew R. Coggan, Ph.D. Cardiovascular Imaging Laboratory Washington University School of Medicine St. Louis, MO 63110
  2. 2. Maximal O2 uptake (VO2max) • • • • • What is it? Why is it important? What determines it? How do you train it? How do you measure it?
  3. 3. VO2max – what is it?
  4. 4. VO2max – what is it? • The highest rate of whole-body oxygen uptake (VO2) achievable during exercise that utilizes a large muscle mass (e.g., running).
  5. 5. Plateau in VO2 with increasing exercise intensity
  6. 6. VO2max – what is it? • The highest rate of whole-body oxygen uptake (VO2) achievable during exercise that utilizes a large muscle mass (e.g., running). • An intrinsic biological characteristic of an individual at any particular point in time.
  7. 7. VO2max – why is it important?
  8. 8. VO2max – why is it important? • VO2max is the best overall measure of cardiovascular fitness and sets the upper limit to the production of energy (ATP) via aerobic metabolism (i.e., mitochondrial respiration). As such, having an adequately high VO2max is a necessary but not a sufficient condition to be an elite endurance athlete.
  9. 9. VO2max in different groups of athletes
  10. 10. VO2max – what determines it?
  11. 11. VO2max – what determines it? • While there are numerous steps involved in the transport of the O2 from the atmosphere to the mitochondria where it is utilized, the primary limiting factor to VO2max is maximal cardiac output, and in particular, maximal stroke volume.
  12. 12. The cardiovascular Fick equation: • The Fick equation represents the relationship of the . . body’s oxygen consumption (VO2) to cardiac output (Q) and the arterial-mixed venous oxygen difference (a-vO2 . diff): . . VO2 = Q x a-vO2 diff . or VO2 = HR x SV x a-vO2 diff During maximal exercise: . VO2max = HRmax x SVmax x a-vO2 diffmax
  13. 13. Relationship between VO2max and maximal cardiac output
  14. 14. Stroke volumes (SV) for different states of training Subjects SV @ rest (ml) SV @ max (ml) Untrained 50-70 80-110 Trained 70-90 110-150 Highly trained 90-110 150-220
  15. 15. VO2max – how do you train it?
  16. 16. Role of genetics in determining baseline VO2max
  17. 17. Role of genetics in determining trainability of VO2max From D. Prud'homme et al., 1984, “Sensitivity of maximal aerobic power to training is genotype-dependent,” Medicine and Science in Sports and Exercise 16(5): 489-493. Copyright 1984 by American College of Sports Medicine. Adapted by permission.
  18. 18. Role of genetics in determining trainability of VO2max . Adapted, by permission, from C. Bouchard et al., 1999, “Familial aggregation of VO 2max response to exercise training: Results from HERITAGE Family Study,” Journal of Applied Physiology 87: 1003-1008.
  19. 19. VO2max – how do you train it? • At least/especially in untrained persons, “ordinary” endurance exercise training, if of sufficient intensity (i.e., >50-60% of VO2max), frequency, and duration will lead to an improvement in VO2max, but • As an individual becomes more fit, it becomes progressively harder and harder to elicit further improvement, necessitating that the exercise intensity be increased if any further gains are to be achieved.
  20. 20. VO2max – how much can it be improved? Training program: • Running “all-out” for 40 min/d, 3 d/wk. • Cycling (on an ergometer) 6 x 5 min on, 2 min off, 3 d/wk. Power during intervals set so that subject achieved VO2max during each effort. Hickson, Bomze, and Holloszy. J Appl Physiol 1977; 42:372-376.
  21. 21. Changes in VO2max over time in a world class team pursuit cyclist Jeukendrup AE, Craig NP, Hawley JA. J Sci Med Sport 2000; 3:414-433.
  22. 22. VO2max – how do you measure it?
  23. 23. VO2max – how do you measure it? • By using a “metabolic cart” (gas analyzers, flow measuring device) to quantify respiratory gas exchange (VO2, CO2 production (VCO2)) across the lungs/at the mouth during an incremental exercise test.
  24. 24. Subject performing VO2max test
  25. 25. Characteristics of “ideal” VO2max test • Total duration 8-12 min • Stages typically 1-3 min in length • Exercise intensity increased by <5-8% of VO2max per stage, at least towards end of test • For athletes, sports-specific mode of exercise: ∴ cyclists → cycling
  26. 26. Calculation of VO2, VCO2, and RER . VO2 = rate of O2 uptake (L/min or mL/min/kg). . VCO2 = rate of CO2 release (L/min or mL/min/kg). . . . VO2 = (VI • FIO2) - (VE • FEO2) . . .. VCO2 = (VE • FECO2) - (VI • FICO2) . . RER = VCO2 / VO2 . . Where VE = expired ventilation; VI = inspired ventilation; FIO2 = fraction of oxygen inspired; FICO2 = fraction of carbon dioxide inspired; FEO2 = fraction of oxygen expired; and FECO2 = fraction of carbon dioxide expired.
  27. 27. Criteria for identification of VO2max • Absolute or relative plateau in VO2 despite increase in O2 demand (e.g., <150 mL/min or <1.5 mL/min/kg increase between stages) • RER > 1.10 • Heart rate w/in 10 beats/min of age-predicted maximum • Blood lactate concentration > 8 mmol/L • Volitional fatigue is not evidence that VO2max has been achieved!
  28. 28. Common problems or errors in determining VO2max • • • • Failure to achieve a clear plateau Inappropriate “cherry picking” of data Inaccurate or miscalibrated gas analyzers Inaccurate measurement of ventilation
  29. 29. Example of a good VO2max test
  30. 30. Power-VO2 relationship
  31. 31. Example of a VO2peak test
  32. 32. Inappropriate “cherry picking” of data
  33. 33. Inaccurate or miscalibrated gas analyzer
  34. 34. Power-VO2 relationship
  35. 35. Inaccurate measurement of ventilation
  36. 36. Power-VO2 relationship
  37. 37. Key Points Maximal O2 uptake:  is the highest rate of whole-body oxygen uptake (VO2) achievable during exercise that utilizes a large muscle mass (e.g., running).  is the best overall measure of cardiovascular fitness.  sets the upper limit to the production of energy (ATP) via aerobic metabolism (i.e., mitochondrial respiration), such that  having an adequately high VO2max is a necessary but not a sufficient condition to be an elite endurance athlete.
  38. 38. Key Points (con’t) Maximal O2 uptake:  is determined approximately equally by both genetic and environmental factors (e.g., training).  can be readily measured using a metabolic cart

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