The effects of one- and two-legged exercise on the lactate and ventilatory threshold

The purpose of this investigation was to compare differences between one- and two-legged exercise on the lactate (LT) and ventilation (VT) threshold. On four separate occasions, eight male volunteer subjects (1-leg \(\dot V_{O_{2_{\max } } } \) =3.36 l · min⁻¹; 2-leg \(\dot V_{O_{2_{\max } } } \) =4.27 l · min⁻¹) performed 1- and 2-legged submaximal and maximal exercise. Submaximal threshold tests for 1- and 2-legs, began with a warm-up at 50 W and then increased every 3 minutes by 16 W and 50 W, respectively. Similar increments occurred every minute for the maximal tests. Venous blood samples were collected during the last 30 s of each work load, whereas noninvasive gas measures were calculated every 30 s. No differences in \(\dot V_{O_2 } \) (l · min⁻¹) were found between 1- and 2-legs at LT or VT, but significant differences (p<0.05) were recorded at a given power output. Lactate concentration ([LA]) was different (p<0.05) between 1-and 2-legs (2.52 vs. 1.97 mmol · l⁻¹) at LT. This suggests it is \(\dot V_{O_2 } \) rather than muscle mass which affects LT and VT. \(\dot V_{O_{2_{\max } } } \) for 1-leg exercise was 79% of the 2-leg value. This implies the central circulation rather than the peripheral muscle is limiting to \(\dot V_{O_{2_{\max } } } \) .