Similar level of impairment in exercise performance and oxygen uptake kinetics in middle-aged men and women with type 2 diabetes

O'Connor E, Kiely C, O'Shea D, Green S, Egana M. Similar level of impairment in exercise performance and oxygen uptake kinetics in middle-aged men and women with type 2 diabetes. Am J Physiol Regul Integr Comp Physiol 303: R70-R76, 2012. First published April 25, 2012; doi:10.1152/ajpregu.00012.2012.-The present study tested the hypothesis that the magnitude of the type 2 diabetes-induced impairments in peak oxygen uptake ((V) over dot(O2)) and (V) over dot(O2) kinetics would be greater in females than males in middle-aged participants. Thirty-two individuals with type 2 diabetes (16 male, 16 female), and 32 age-and body mass index (BMI)-matched healthy individuals (16 male, 16 female) were recruited. Initially, the ventilatory threshold (VT) and peak (V) over dot(O2) were determined. On a separate day, subjects completed four 6-min bouts of constant-load cycling at 80% VT for the determination of (V) over dot(O2) kinetics using standard procedures. Cardiac output (CO) (inert gas rebreathing) was recorded at rest, 30, and 240 s during two additional bouts. Peak (V) over dot(O2) (ml.kg(-1).min(-1)) was significantly reduced in men and women with type 2 diabetes compared with their respective nondiabetic counterparts (men, 27.8 +/- 4.4 vs. 31.1 +/- 6.2 ml.kg(-1).min(-1); women, 19.4 +/- 4.1 vs. 21.4 +/- 2.9 ml.kg(-1).min(-1)). The time constant (s) of phase 2 (tau(2)) and mean response time (s) of the (V) over dot(O2) response (MRT) were slowed in women with type 2 diabetes compared with healthy women (tau(2), 43.3 +/- 9.8 vs. 33.6 +/- 10.0 s; MRT, 51.7 +/- 9.4 vs. 43.5 +/- 11.4s) and in men with type 2 diabetes compared with nondiabetic men (tau(2), 43.8 +/- 12.0 vs. 35.3 +/- 9.5 s; MRT, 57.6 +/- 8.3 vs. 47.3 +/- 9.3 s). The magnitude of these impairments was not different between males and females. The steady-state CO responses or the dynamic responses of CO were not affected by type 2 diabetes among men or women. The results suggest that the type 2 diabetes-induced impairments in peak (V) over dot(O2) and (V) over dot(O2) kinetics are not affected by sex in middle aged participants.