The effects of unilateral Swedish massage on the neural activities measured by quantitative electroencephalography (EEG)

Abstract

Purpose It is generally accepted that massage can provide a lot of benefits to human health, especially for the brain functions. Little is known about the effect of unilateral massage on the brain activities. Nowadays, Swedish massage is a modern massage technique that is popular in both treatment and research fields. The purpose of this paper is to investigate the effect of unilateral Swedish massage on brain activities with electroencephalography (EEG) recording. Design/methodology/approach In total, 18 healthy adult participants (5 men, 13 women) aged between 22 and 36 years were massaged over one side of arm, forearm, hand, neck and face. Then the same procedures were repeated to another side of the body. EEG was recorded before (baseline) and during each massage condition. The absolute power of four common brain waves consisting of δ (0.5-4 Hz), θ (4-8 Hz), α (8-13 Hz), and β activities (13-30 Hz) from the quantitative EEG analysis between baseline and each massage condition were used to compare with the paired t-test. Findings The study found the reduction of δ and θ powers over bilateral frontal, fronto-central, and central areas. The increments of α power over the similar brain areas were also observed. These findings indicated the generalized effect of unilateral Swedish massage for inducing relaxation. Moreover, the significant reduction of β power was also found over right central area when left-arm massage was applied. This finding revealed the initial inhibitory effect of Swedish massage over right somatosensory cortex that received sensory stimulation through massage from left side of the body. Originality/value Unilateral Swedish massage induced the inhibitory effect at the contralateral somatosensory cortex and then produced the generalized effect which is compatible with relaxation.