Acute effects of vibration on thermal perception thresholds
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/s2 (r.m.s.), corresponding to a 8-h equivalent acceleration, A(8) of 0.46 and 0.92 m/s2, 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°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.
KeywordsHand–arm Vibration Thermal perception Finger Threshold Neurological
This research was supported by the European Commission under the Quality of Life and Management of Living Resources programme (project number QLK4-2002-02650 VIBRISKS) and the Swedish Council for Work Life Research (project number 2004-0838). A special thanks to Rebecka Vilhelmsson for her statistical analysis.
- Bovenzi M (1997) Hand-transmitted vibration. In: Stellman JM (ed) Encyclopaedia of occupational health and safety, vol 2, Part IV, Chap 50, International Labour Office, Geneva, pp 7–12Google Scholar
- Ekenvall L, Gemne G, Tegner R (1989) Correspondence between neurological symptoms and outcome of quantitative sensory testing in the hand–arm vibration syndrome. Br J lnd Med 46:570–574Google Scholar
- European Council (2002) Directive 2002/44/EC of the European parliament and of the Council of 25 June 2002 on the minimum health and safety requirements regarding the exposure of workers to the risks rising from physical gents (vibration) (sixteenth individual directive within the meaning of Article 16(1) of Directive 89/391/EEC). Off J Eur Commun L 177:13–19Google Scholar
- Girden ER (1992) ANOVA repeated measures, Sage Publications, Newbury ParkGoogle Scholar
- Griffin MJ (1990) Handbook of human vibration, Academic, LondonGoogle Scholar
- International Organisation for Standardisation, ISO (2001) Mechanical vibration—measurement and evaluation of human exposure to hand-transmitted vibration—Part 1: General guidelines. ISO 5349-1. ISO, GenevaGoogle Scholar
- Lindsell CJ, Griffin MJ (1998) Standardised diagnostic methods for assessing components of the hand–arm vibration syndrome. Health & Safety Executive, UK, contract research report CRR 197Google Scholar