Interactions of personal and occupational risk factors on hand grip strength of winter pruners

Background: Winter pruning is an important procedure to sustain the yield and quality of vineyards. Pruning shears are commonly used in this stage. Handling pruning shears may cause work-related musculoskeletal disorders (MSDs). Physical load on pruners at varying intensities and repetitive movements increase the risk of muscle strength and hand-wrist disorders. Grip strength (GS) is well accepted measure of muscle strength. The ambient temperature also affects pruners during winter pruning. Purpose: The purpose of this study was to determine the effects of different type of pruning shears, working ambient temperatures, work experiences of pruners, anthropometric values of the pruners and working hours on the GS values of professional pruners. Methods: The study was conducted with the participation of professional volunteer pruners during winter pruning in Sultanas' vineyards. The GS values determined from both hands of pruners in a group of rural workers (n = 18), was evaluated five different times during continuous 18 days of the pruning period. The GS values of pruners were measured using a digital hand dynamometer. The standard anthropometric measurement set was used to determine the anthropometric values of the pruners. Results: The average GS values of pruners' the dominant and non-dominant hands were found to be 363 +/- 89 N and 347 +/- 86 N, respectively. Except working hours, all other parameters were found r-value and p-value for correlation with GS. GS decreased with increased age (r =- 0.473, p = 0.000). Furthermore, the effect of pruning shears on GS was statistically significant. For dominant hand, the highest GS was observed with the pruning shear with an anvil blade (386 +/- 86 N); the lowest GS was observed with the pruning shear with a rotating lower handle (296 +/- 55 N). Changes in the temperature of the work environment during a long pruning period had a significant effect on the GS values. The GS values increased with decreasing work environment temperature. Conclusions: GS values of the dominant hand had a greater value than that of the non-dominant hand which is reported in the literature. The study finding for anthropometric dimensions and GS values of pruners was significant. An adverse effect between work ambient temperature and GS values was revealed in winter pruners. GS values were not statistically significant, however, there was found slightly increasing and decreasing effects during the morning and afternoon hours, respectively. The type of the pruning shears affected the GS values. Relevance to industry: It is believed that the findings will inform ergonomists about the potential risk of MSDs during pruning. The results obtained in this study will contribute to ergonomic solutions in a new-product design, in particular choosing the more appropriate equipment to meet the needs of pruners.