Central and Regional Circulatory Effects of Adding Arm Exercise to Leg Exercise

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Abstract
7 young, healthy, male subjects performed exercise on bicycle ergometers in two 20 min periods with an interval of 1 h. The first 10 min of each 20 min period consisted of arm exercise (38–62% of Vdot;o2max for arm exercise) or leg exercise (58–78% of Vdot;o2max for leg exercise). During the last 10 min the subjects performed combined arm and leg exercise (71–83% of Vdot;o2max for this type of exercise). The following variables were measured during each type of exercise: oxygen uptake, heart rate, mean arterial blood pressure, cardiac output, leg blood flow (only during leg exercise and combined exercise), arterio‐venous concentration differences for O2and lactate at the levels of the axillary and the external iliac vessels.Superimposing a sufficiently strenuous arm exercise (oxygen uptake for arm exercise 40% of oxygen uptake for combined exercise) on leg exercise caused a reduction in blood flow and oxygen uptake in the exercising legs with unchanged mean arterial blood pressure. Superimposing leg exercise on arm exercise caused a decrease in mean arterial blood pressure and an increased axillary arterio‐venous oxygen difference. These findings indicate that the oxygen supply to one large group of exercising muscles may be limited by vasoconstriction or by a fall in arterial pressure, when another large group of muscles is exercising simultaneously.