Department of Physiology, Trinity College Dublin, Dublin, Ireland.
Med Sci Sports Exerc. 2011 Jun;43(6):935-42. doi: 10.1249/MSS.0b013e3182061cdb.
This study aimed to investigate whether cardiac output (CO) responses were related to VO2 kinetics during cycling in type 2 diabetes.
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 VO2 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 VO2 (50% Δ). CO (inert gas rebreathing) was recorded at 30 and 240 s of an additional bout at each intensity. VO2 kinetic parameters were determined by fitting a biexponential (50% VT and 80% VT) or triexponential (50% Δ) function to the VO2 data.
Peak VO2 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 VO2 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.
The results confirm that type 2 diabetes slows the dynamic response of VO2 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.
本研究旨在探讨 2 型糖尿病患者在踏车运动中，心输出量（CO）反应与 VO2 动力学之间是否存在相关性。
共招募 9 名中年女性 2 型糖尿病患者、9 名非糖尿病超重女性和 11 名非糖尿病瘦型女性。首先，在最大递增测试中确定了通气阈（VT）和峰值 VO2。然后，在两天的时间里，受试者在三个不同强度下分别完成了三次 7 分钟的恒负荷踏车运动：50%VT、80%VT 和 VT 与峰值 VO2 之间的中点（50%Δ）。在每个强度下，在额外的一次运动的 30 和 240 秒时记录 CO（惰性气体重复呼吸）。通过将双指数（50%VT 和 80%VT）或三指数（50%Δ）函数拟合到 VO2 数据，确定 VO2 动力学参数。
与非糖尿病组相比，2 型糖尿病患者的峰值 VO2 显著降低（P<0.05）。在 50%VT（34.2±15.7 比 15.4±7.3 和 20.2±9.7 s）和 80%VT（39.1±9.0 比 24.8±8.8 和 36.8±7.9 s）时，2 型糖尿病患者的相 2 时间常数显著增大（P<0.05），但在 50%Δ时，所有 VO2 动力学参数均无差异。三组患者运动中的 CO 反应无差异，在 80%VT 时，2 型糖尿病患者从 30 到 240 秒的 CO 变化明显大于非糖尿病组。
研究结果证实，2 型糖尿病女性在轻中度相对强度运动中，VO2 的动态反应速度较慢，但在运动初期 CO 反应并没有减慢。
