Object shape affects hand grip function for heavy objects in younger and older adults

Hand-grip function while lifting objects is essential for performing everyday tasks. The Box and Block Test (BBT) has been used to assess hand-grip function and dexterity, but only light objects have been used. The purpose of this study was to investigate the effects of block surface, shape, age, and sex on hand dexterity during the movement of heavy blocks in the BBT. Forty healthy participants comprised of a younger group of 10 males (M =  22.50 years, SD = 2.01) and 10 females (M  =  22.20 years, SD = 2.66) between 20 and 30-years-old, and an older group of 10 males (M = 55.80 years, SD = 3.19) and 10 females (M = 55.90 years, SD = 2.56) between 50 and 60-years-old, performed the BBT using steel objects of different shapes (cylindrical and cubic) and different surfaces (plain steel, black spray-painted steel, and yellow non-slip spray-painted steel). The results indicated that repetition and shape had significant effects on the BBT score. Previous researchers have found that surface textures, age, and sex influenced hand dexterity for light objects, but these effects were not discovered in the current study. These findings suggest that shape should take priority over age, sex, and surface texture when designing tools to improve user handling. Practitioner Summary: Hand-grip function is critically important when performing daily grip tasks such as picking up a writing utensil, using a toothbrush, or twisting a hand tool. The shape should be considered during the design process of tools and equipment used in industry so that handling can be made for the user. Abbreviations: BBT: box and block test; COF: coefficient of friction; BPS: blocks per second.