Pulmonary diffusion and aerobic capacity: is there a relation? Does obesity matter?
OBJECTIVE
We sought to determine whether pulmonary diffusing capacity for nitric oxide (DLNO), carbon monoxide (DLCO) and pulmonary capillary blood volume (Vc) at rest predict peak aerobic capacity (VO2peak), and if so, to discern which measure predicts better.


METHODS
Thirty-five individuals with extreme obesity (body mass index or BMI = 50 +/- 8 kg m((-2)) and 26 fit, non-obese subjects (BMI = 23 +/- 2 kg m((-2)) participated. DLNO and DLCO at rest were first measured. Then, subjects performed a graded exercise test on a cycle ergometer to determine (VO2peak). Multivariate regression was used to assess relations in the data.


RESULTS
Findings indicate that (i) pulmonary diffusion at rest predicts (VO2peak) in the fit and obese when measured with DLNO, but only in the fit when measured with DLCO; (ii) the observed relation between pulmonary diffusion at rest and (VO2peak) is different in the fit and obese; (iii) DLNO explains (VO2peak) better than DLCO or Vc. The findings imply the following reference equations for DLNO: (VO2peak) (mL kg(-1) min(-1)) = 6.81 + 0.27 x DLNO for fit individuals; (VO2peak) (mL kg(-1) min(-1)) = 6.81 + 0.06 x DLNO, for obese individuals (in both groups, adjusted R(2 )=( )0.92; RMSE = 5.58).


CONCLUSIONS
Pulmonary diffusion at rest predicts (VO2peak), although a relation exists for obese subjects only when DLNO is used, and the magnitude of the relation depends on gender when either DLCO or Vc is used. We recommend DLNO as a measure of pulmonary diffusion, both for its ease of collection as well as its tighter relation with (VO2peak).
Zavorsky
G S
GS
Department of Obstetrics, Gynecology and Women's Health, Saint Mary's Health Center, Saint Louis University, MO 63117, USA. zavorsky@slu.edu <zavorsky@slu.edu>
Wilson
B
B
Harris
J K
JK
Kim
D J
DJ
Carli
F
F
Mayo
N E
NE
D000328:Adult; D002248:Carbon Monoxide / Q000494:pharmacology*; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D017079:Exercise Tolerance; D006801:Humans; D008297:Male; D008875:Middle Aged; D009569:Nitric Oxide / Q000502:physiology; D009765:Obesity / Q000139:chemically induced / Q000503:physiopathology*; D010100:Oxygen / Q000378:metabolism*; D010101:Oxygen Consumption / Q000502:physiology; D005082:Physical Exertion / Q000502:physiology; D011650:Pulmonary Alveoli / Q000502:physiology*; D011653:Pulmonary Diffusing Capacity / Q000187:drug effects / Q000502:physiology*; D012129:Respiratory Function Tests / Q000379:methods
D009569:Nitric Oxide; D002248:Carbon Monoxide; D010100:Oxygen