Effect of contralateral limb exercise on peripheral perfusion index in a resting limb

Background & objectives Following surgical treatment and subsequent immobilisation of one limb, physiological reductions in blood flow are expected due to limited or no movement. This study was designed to investigate the change in perfusion index in a resting limb when the contralateral limb exercises (active and passive). Methods This was a two-arm comparative study with 39 healthy participants (22 males, 17 females) with a mean (SD) age of 23.4 (5.2) years. One limb was set to exercise (active and passive in different sessions), and another limb rested with a pre-designed exercise protocol. We measured perfusion index in exercising and non-exercising limbs after 3, 4, 5, and 6 min of exercise. Results In resting upper limbs, there was an increase in the perfusion index during both active and passive exercise of the contralateral limb (achieved at 3 min in active and 4 min in passive exercise). In resting lower limbs, in active exercise, the increase in perfusion index occurred at 4 min and 6 min of exercise. In passive exercise, there was no significant change in perfusion index. Interpretation & conclusions Active exercise of one limb significantly increases blood flow in the opposite, resting limb. This effect is not found in passive exercise in the lower limb. Hence, when one limb undergoes surgery, for a higher perfusion on that limb, an active exercise or passive exercise in the upper limb, or active exercise in the lower limb may be beneficial.