Fitness (VO2MAX) Testing

What is VO2 MAX?

VO2MAX (peak oxygen consumption) is the term that is used to describe the highest capability of the body to use oxygen to power exercise. it is primarily determined by two things:

• The ability to get oxygen to working tissue (muscles, organs, etc)
• The ability of target organs or muscle to remove oxygen from the bloodstream and use it

In the context of exercise, oxygen consumption tends to rise as work (exercise) increases. Thus, oxygen consumption (or “VO2”) can be considered a proxy for exercise capacity (or level of “fitness”).

Over the course of the last twenty years, medical research has firmly established that a person’s level of fitness (as measured through VO2MAX testing) is an independent predictor of risk of early death. An “independent” risk factor is one that is a risk all by itself. In other words, low fitness is a risk, not because of its relationship to obesity, or its relationship to high blood sugar, or high blood pressure, but because the absence of an active lifestyle puts a person at higher risk for sudden death even if body weight is normal, blood sugars are normal and blood pressure is controlled. Here is what we know about the actual risks associated with a low VO2MAX:

• People whose blood pressure is normal, have a higher likelihood of developing high blood pressure if their VO2MAX is low. 1 2
• Low fitness level as measured by VO2MAX testing is a strong independent predictor of development of Metabolic Syndrome (obesity, high blood pressure, high cholesterol and impaired control of blood sugars).3 4 5 6 Conversely, raising one’s VO2MAX through exercise is a more effective method of treating established metabolic syndrome than prescription medication! 7
• In studies of non-diabetic men, low fitness level as measured by VO2MAX testing (lower 20%) carries a 370% increased risk for development of diabetes in comparison with those who are most fit. 8
• Low fitness level as measured by VO2MAX testing is associated with high levels of CRP and other markers for vascular inflammation (a risk factor for heart attack)  9 10
• Low fitness level as measured by VO2MAX testing is associated with an increased independent risk for both cardiovascular death and death from “all causes”. 11 12 13 This holds true across many different patient populations evaluated, including:
  • Otherwise healthy men and women 14 15 16
  • Men and women with the Metabolic Syndrome 17
  • Patients with established high blood pressure 18
  • Patients who are overweight
  • Patients with diabetes 19 20
• The mortality risk for “low fitness” is about the same as the mortality risk from having diabetes. Another review of the data showed that people with low fitness levels have about a 70% higher risk of death from any cause relative to those with higher fitness levels, and 56% higher risk of heart attack or stroke. When risks of this group were compared to those with “moderate” fitness levels, there was still an increased risk of early death of 40% all-cause and 47% cardiac-related mortality! Moreover, patients who exercise and demonstrably increase their level of fitness reduce their risk for early death. 21
• Most of the mortality risk in patients with obesity of the Metabolic syndrome seem to relate to underlying low fitness levels rather than (for example) the degree of obesity present itself 22 23

Does my overall activity level predict my risk for heart attack or stroke as well as VO2MAX testing?

A few studies show a correlation between the level of exercise reported and fitness levels, but when this question was analyzed by grouping together multiple studies asking the same question, low “fitness” as measured by VO2MAX testing was most closely correlated with risk. Knowing what we do about the risks of inactivity, it is unlikely that the issue here is that low activity isn’t risky – just that pigeonholing people into categories based on their activity level is problematic. This, measurement of VO2MAX appears to be an important component of clinical risk assessment, because it is objective, reproducible, comparable between groups or across time and can be easily measured.

How much will my overall risk decrease if my fitness level improves?

Generally, an increase in activity of 1000 kcal/week will translate to an increase in fitness of one MET (a MET is 3.5cc of oxygen/kg/min [don’t worry, you won’t be tested on this…])/ The difference between riding in a golf cart and walking is about a MET. An increase in fitness of one MET has been associated with a 13% risk reduction in all-cause mortality, and 15% risk reduction for heart disease.

1 Barlow CE, LaMonte MJ, Fitzgerald SJ, Kampert JB, Perrin JL, Blair SN. Cardiorespiratory fitness is an independent predictor of hypertension incidence among initially normotensive healthy women. Am J Epidemiol. 2006 Jan 15;163(2):142-50.

2 Blair SN, Goodyear NN, Gibbons LW, Cooper KH. Physical fitness and incidence of hypertension in healthy normotensive men and women. JAMA. 1984 Jul 27;252(4):487-90.

3 LaMonte MJ, Barlow CE, Jurca R, Kampert JB, Church TS, Blair SN. Cardiorespiratory fitness is inversely associated with the incidence of metabolic syndrome: a prospective study of men and women. Circulation. 2005 Jul;112(4):505-12.

4 Finley CE, LaMonte MJ, Waslien CI, Barlow CE, Blair SN, Nichaman MZ. Cardiorespiratory fitness, macronutrient intake, and the metabolic syndrome: the Aerobics Center Longitudinal Study. J Am Diet Assoc. 2006 May;106(5):673-9

6 Lakka TA, Laaksonen DE, Lakka H-A, Mannikko N, Niskanen LK, Rauramaa R, Salonen JT. Sedentary lifestyle, poor cardiorespiratory fitness, and the metabolic syndrome. Med Sci Sports Exerc. 2003;35(8):1279-86.

7 Knowler WC. Reduction in the incidence of type 2 diabetes with lifestyle intervention or metformin. NEJM 2002 Feb;345(6):393-403.

8 Wei M, Gibbons LW, Mitchell TL, Kampert JB, Lee CD, Blair SN. The association between cardiorespiratory fitness and impaired fasting glucose and type II diabetes mellitus in men. Ann Int Med. 1999 Jan;130(2):89-96.

9 LaMonte MJ, Ainsworth BE, Durstine JL. Influence of cardiorespiratory fitness on the association between C-reactive protein and metabolic syndrome prevalence in racially diverse women. J Womens Health (Larchmt). 2005 Apr;14(3):233-9

10 Jae SY. Relation of cardiorespiratory fitness to inflammatory markers, fibrinolytic factors, and lipoprotein(a) in patients with type 2 diabetes mellitus. Am J Cardiol 2008 Sep;102(6):700-3

11 Williams PT. Physical fitness and activity as separate heart disease risk factors: a meta-analysis. Med Sci Sports Exerc. 2001;33(5):754-61.

12 Katzmarzyk PT, Church TS, Janssen I, Ross R, Blair SN. Metabolic syndrome, obesity and mortality: impact of cardiorespiratory fitness. Diabetes Care. 2005 Feb;28(2):391-7

13 Myers J, Prakash, M, Froelicher V, Do D, Partington S, Atwood E. Exercise capacity and mortality among men referred for exercise testing. NEJM 2002;346(11)793-801.

14 Farrell SW, Braun L, Barlow CE, Cheng YJ, Blair SN. The relation of body mass index, cardiorespiratory fitness and all-cause mortality in women. Obes Res. 2002 Jun;10(6):417-23.

15 Wei M, Kampert JB, Barlow CE, Nichaman MZ, Gibbons LW, Paffenberger RS, Blair SN. Relationship between low cardiorespiratory fitness and mortality in normal-weight, overweight and obese men. JAMA. 1999 Oct;28(16):1547-53.

16 Blair SN, Kohl HW, Paffenberger RS, Clark DG, Cooper KH, Gibbons LW. Physical fitness and all-cause mortality. A prospective study of healthy men and women. JAMA. 1989 Nov;262(17):2395-401

17 Katzmarzky PT, Church TS, Blair SN. Cardiorespiratory fitness attenuates the effects of the metabolic syndrome on all-cause and cardiovascular disease mortality in men. Arch Intern Med. 2004 May;164(10)1092-7.

18 Church TS, Kampert JB, Gibbons LW, Barlow CE, Blair SN. Usefulness of cardiorespiratory fitness as a predictor of all-cause and cardiovascular mortality in men with systemic hypertension. Am J Cardiol. 2001 Sept;88(6)651-6.

19 Church TS, Cheng YJ, Earnest CP, Barlow CE, Gibbons LW, Priest EL, Blair SN. Exercise Capacity and body composition as predictors of mortality among men with diabetes. Diabetes Care. 2004 Jan;27(1):83-8.

20 Church TS, LaMonte MJ, Barlow CE, Blair SN. Cardiorespiratory fitness and body mass index as predictors of cardiovascular disease mortality among men with diabetes. Arch Int Med. 2006 Jun;166(12):1326-7.

21 Blair SN. Changes in physical fitness and all-cause mortality. A prospective study of healthy and unhealthy men. JAMA 1995 Apr;273(14):1093-8.

22 Lee S, Kuk JL, Katzmarzyk PT, Blair SN, Church TS, Ross R. Cardiorespiratory fitness attenuates metabolic risk independent of abdominal subcutaneous and visceral fat in men. Diabetes Care. 2005 Apr;28(4):895-901.

23 Blair SN. Influences of cardiorespiratory fitness and other precursors on cardiovascular disease and all-cause mortality in men and women. JAMA. 1996 Jul;276(3):205-10.