Combined effects of force and vibration on the human hand

Abstract

The combined effect of force and hand-arm vibration (HAV) exposure on human hand is considered to be highly influential, yet it remains an understudied area of research. This study aimed to investigate the acute effect of hand force during vibration exposure on human physiological responses, particularly focusing on the neural and vascular systems. It was an experiment-based study that examined the acute effects on healthy subjects by exposing them to various combinations of force loadings and vibrations. The first study focused on the vibration-induced vascular effects, specifically the weakening of peripheral blood circulation. Participants experienced different force levels and moderate vibrations. Measurements of finger blood flow and finger skin temperature were conducted during and after the exposure to force and vibration. The results revealed that hand force had a stronger influence on circulation than vibration. Clear reductions in finger blood flow and finger skin temperature were observed with hand force, while the additional impact of vibration was not significant. Moreover, a higher grip force exerted a greater influence on circulation compared to a push force. The second study focused on the vibration-induced neurological effects, particularly temporary shifts in vibration and thermal perception thresholds. Participants were exposed to different conditions with two levels of vibration and moderate force levels. Measurements on thresholds were tested following vibration and force exposure. The results showed vibration levels significantly influenced neurological responses. Hand force had a notable effect on small vibration magnitudes but diminished for larger vibrations. In the third study, the acute vascular response to short-term HAV was further investigated. Participants underwent a similar experimental procedure with the same combinations of force loadings and vibrations as in the second study, but with a slightly different posture. Combining the results of the second and third studies, it was observed that both the nervous and circulatory systems were sensitive to force and vibration. Responses decreased as vibration and force intensity increased, with the nervous system showing higher sensitivity to vibration. The final study aimed to refine the exposure conditions to quantify the cause-effect relationship between force, vibration stimuli and the physiological response. Both factors were expanded on a larger scale to assess their relative significance. Temporary shifts in vibration perception thresholds were used for analysis. A fitting of the response results was provided, demonstrating that human responses were influenced by both force and vibration levels, highlighting their interdependent relationship.

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Identifiers

ORCID for Shuxiang Gao: orcid.org/0000-0003-0119-8445

ORCID for Ying Ye: orcid.org/0000-0002-7721-5451

ORCID for David Simpson: orcid.org/0000-0001-9072-5088

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