Hand dimensions and grip strength: A comparison of manual and non-manual workers

Abstract

The purpose of this study was to examine grip strength differences between manual and non-manual workers and to investigate possible contributors. The sample consisted of 1740 adult males aged between 20–64 years old including 905 manual (40.5 ± 16.8 years) and 835 non-manual workers (48.3 ± 18.2 years). The first group was manual unskilled workers who perform light manual operations. Non-manual workers were office/clerical employees who spent the majority of their time behind a computer. Hand dimensions (palm width, hand length, palm length, forearm length, wrist circumference and forearm circumference) were measured by a digital Caliper (±0.1 mm) and a tape meter (±0.1 cm) with respect to the NASA standards. The values of grip strength were measured by JAMAR hydraulic dynamometer according to the ASHAT recommendations. The mean hand grip strength of manual workers (51.6 ± 8.7 kg) was significantly higher than that of non-manual workers (45.2 ± 5.8 kg) (P < 0.001). Concerning hand dimensions, Palm width and forearm circumference were significantly greater in manual workers than in non-manual workers (range of difference: 0.5–2.3 cm for palm width and 1.1–2.8 cm for forearm circumference). Other hand dimensions were not statistically different between the two job groups. Among all selected hand dimensions, palm width and forearm circumference had the greatest relationship with grip strength (r = 0.71, p < 0.001 for manual workers; r = 0.66, p < 0.001 for non-manual workers). This study revealed that light manual workers are approximately 12.4% stronger than office employees in hand grip. It is important to take the observed differences into account in clinical as well as design settings.