Variable physical functions in individuals in response to sensory stimuli

Abstract

Purpose Sensory stimulation affects physical function; however, the type and range of physical function change remain unclear. This study aimed to evaluate the type and extent of changes in simple physical functions resulting from exposure to color and taste stimuli. Methods Five basic colors (red, blue, yellow, green, and black) and foods representative of the five basic tastes (sweet, sour, salty, bitter, and umami) were used as stimuli. Three different physical function tests on muscle strength (grip strength), flexibility (bending length), and balance (stabilometer trajectory area) were performed while wearing color-tinted goggles or after tasting food stimuli. All the stimuli tests were performed in 1 day and repeated for 6 successive days each for color and taste stimuli. Results Each stimulus had a different effect on the participants. For color stimulation, the median change ratio between the minimum and maximum effects was 5.68% (4.14–8.07%) for muscle strength, 8.52% (5.11–13.39%) for flexibility, and 30.60% (26.81–36.18%) for balance. The corresponding values for taste stimulation were 4.96% (3.67–7.89%), 6.11% (4.37–8.86%), and 28.92% (21.38–34.01%). The rate of change in balance was the highest among the three physical tests and was significantly different from the rate of change in other physical functions (balance vs. muscle power, P < 0.001; balance vs. flexibility, P < 0.001). Conclusion Color and taste stimuli have different effects on physical function, with individual-level differences in sensitivity to stimuli. Sensory stimuli may affect individual physical functions.