Burström Lage, Lundström Ronnie, Sjödin Fredrik, Lindmark Asta, Lindkvist Markus, Hagberg Mats, Nilsson Tohr
Department of Public Health and Clinical Medicine, Umeå University, Umeå, Sweden.
Int Arch Occup Environ Health. 2008 Apr;81(5):603-11. doi: 10.1007/s00420-007-0266-0. Epub 2007 Oct 6.
This study focuses on the acute effects of vibration and how vibrations influence the measures of the thermal perception thresholds during different vibration magnitudes, frequencies, and durations.
The fingers of ten healthy subjects, five males and five females, were exposed to vibration under 16 conditions with a combination of different frequency, intensity and exposure time. The vibration frequency was 31.5 and 125 Hz and exposure lasted between 2 and 16 min. The energy-equivalent frequency weighted acceleration, according to ISO 5349-1, for the experimental time of 16 min was 2.5 or 5.0 m/s(2) (r.m.s.), corresponding to a 8-h equivalent acceleration, A(8) of 0.46 and 0.92 m/s(2), respectively. A measure of the thermal perception of cold and warmth was conducted before the different exposures to vibration. Immediately after the vibration exposure the acute effect was measured continuously on the exposed index finger for the first 75 s, followed by 30 s of measures at every minute for a maximum of 10 min. If the subject's thermal thresholds had not recovered, the measures continued for a maximum of 30 min with measurements taken every 5 min.
For all experimental conditions and 30 s after exposure, the mean changes of the thresholds compared with the pre-test were found to be 0.05 and -0.67 degrees C for the warmth and cold thresholds, respectively. The effect of the vibration exposure was only significant on the cold threshold and only for the first minute after exposure when the threshold was decreased. The warmth threshold was not significantly affected at all. The frequency and the exposure time of the vibration stimuli had no significant influence on the perception thresholds for the sensation of cold or warmth. Increased equivalent frequency weighted acceleration resulted in a significant decrease of the subjects' cold threshold, not the warmth. The thresholds were unaffected when changes in the vibration magnitude were expressed as the frequency weighted acceleration or the unweighted acceleration.
When testing for the thermotactile thresholds, exposure to vibration on the day of a test might influence the results. Until further knowledge is obtained the previous praxis of 2 h avoidance of vibration exposure before assessment is recommended.
本研究聚焦于振动的急性效应，以及在不同振动幅度、频率和持续时间下，振动如何影响热感觉阈值的测量。
10名健康受试者（5名男性和5名女性）的手指在16种不同频率、强度和暴露时间组合的条件下接受振动。振动频率为31.5Hz和125Hz，暴露持续2至16分钟。根据ISO 5349-1标准，16分钟实验时间的能量等效频率加权加速度为2.5或5.0m/s²（均方根），分别对应8小时等效加速度A(8)为0.46和0.92m/s²。在不同振动暴露之前，对冷和暖的热感觉进行测量。振动暴露后立即在暴露的食指上连续测量前75秒的急性效应，随后每分钟测量30秒，最长持续10分钟。如果受试者的热阈值未恢复，则最多持续30分钟，每5分钟测量一次。
在所有实验条件下以及暴露后30秒，与测试前相比，暖阈值和冷阈值的平均变化分别为0.05℃和-0.67℃。振动暴露的影响仅在冷阈值上显著，且仅在暴露后的第一分钟阈值降低时显著。暖阈值根本没有受到显著影响。振动刺激的频率和暴露时间对冷或暖感觉的感知阈值没有显著影响。等效频率加权加速度增加导致受试者冷阈值显著降低，而非暖阈值。当振动幅度的变化表示为频率加权加速度或未加权加速度时，阈值不受影响。
在测试热触觉阈值时，测试当天暴露于振动可能会影响结果。在获得更多知识之前，建议在评估前避免振动暴露2小时的先前做法。
