Skip Navigation LinksHome > June 2011 - Volume 43 - Issue 6 > Cardiac Output Is Not Related to the Slowed O2 Uptake Kineti...
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Medicine & Science in Sports & Exercise:
doi: 10.1249/MSS.0b013e3182061cdb
Clinical Sciences

Cardiac Output Is Not Related to the Slowed O2 Uptake Kinetics in Type 2 Diabetes

MAC ANANEY, OSCAR1; MALONE, JOHN1; WARMINGTON, STUART2; O'SHEA, DONAL3; GREEN, SIMON4; EGAÑA, MIKEL1

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Abstract

Purpose: This study aimed to investigate whether cardiac output (CO) responses were related to V˙O2 kinetics during cycling in type 2 diabetes.

Methods: A total of 9 middle-aged women with uncomplicated type 2 diabetes, 9 nondiabetic overweight women, and 11 nondiabetic lean women were recruited. Initially, the ventilatory threshold (VT) and peak V˙O2 were determined during a maximal graded test. Then, on two separate days, subjects completed three 7-min bouts of constant-load cycling at each of three intensities: 50% VT, 80% VT, and midpoint between VT and peak V˙O2 (50% Δ). CO (inert gas rebreathing) was recorded at 30 and 240 s of an additional bout at each intensity. V˙O2 kinetic parameters were determined by fitting a biexponential (50% VT and 80% VT) or triexponential (50% Δ) function to the V˙O2 data.

Results: Peak V˙O2 was significantly lower in type 2 diabetes compared with the two nondiabetic groups (P < 0.05). The time constant of phase 2 was significantly greater (P < 0.05) in type 2 diabetes compared with the nondiabetic heavy and lean groups at 50% VT (34.2 ± 15.7 vs 15.4 ± 7.3 and 20.2 ± 9.7 s) and 80% VT (39.1 ± 9.0 vs 24.8 ± 8.8 and 36.8 ± 7.9 s), but none of the V˙O2 kinetic parameters were different at 50% Δ. CO responses during exercise were not different among the three groups, and at 80% VT, the change in CO from 30 to 240 s was significantly larger in type 2 diabetes compared with the two nondiabetic groups.

Conclusions: The results confirm that type 2 diabetes slows the dynamic response of V˙O2 during light and moderate relative intensity exercise in females but that this occurs in the absence of any slowing of the CO response during the initial period of exercise.

©2011The American College of Sports Medicine

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