Grip Force Vectors for Varying Handle Diameters and Hand Sizes

Abstract

Grip force was measured along two orthogonal axes and vector summed. Sixty-one participants recruited from a manufacturing facility (29 men and 32 women) grasped instrumented cylinders (2.54, 3.81, 5.08, 6.35, and 7.62 cm diameter) using a maximal voluntary power grip. Two orthogonal force measurements relative to the third metacarpal were resolved into a magnitude and corresponding angle. On average, magnitude increased 34.8 N as handle diameter increased from 2.54 cm to 3.81 cm, and then monotonically declined 103.8 N as the handle diameter increased to 7.62 cm. The average direction monotonically decreased from 59.2 degrees to 37.7 degrees as handle diameter decreased from the largest to the smallest. When the diameter was smallest, the greatest force component, Fx (168.6 N), was in the direction where the fingertips opposed the palm. Conversely, when the diameter was largest, the smallest component, Fx (77.7 N), was in the same direction. These values are averaged for the left and right hand. The angle for the largest diameter increased with increasing hand size. These relationships should be useful for the design of handles that require gripping in specific directions, such as for hand tools and controls. Actual or potential applications of this research include the design of handles that require gripping in specific directions, such as for hand tools and controls, that reduce effort, and that prevent fatigue and overexertion.

Investigating interrelationships between Lower Palaeolithic stone tool effectiveness and tool user biometric variation: implications for technological and evolutionary changes

“…Relative to what is known about how stone tool related behaviours may have influenced the evolution of human hand anatomy, however, a great deal less has been empirically demonstrated in respect to how biometric variation may have impacted on technological choices and cultural variability in the Lower Palaeolithic. The notion that individual biometric differences significantly influence hand-held tool use or gripping tasks is, however, both long lived and widely supported within engineering and ergonomic literature (e.g., Tichauer and Gage, 1977;Hall, 1997;Ruiz-Ruiz et al, 2002;Edgren et al, 2004;Nicolay and Walker, 2005;Hwang et al, 2011), with it having been demonstrated on a number of occasions that optimal tool forms are directly related to the biometric traits of tool users (e.g., Eksioglu, 2004;Seo and Armstrong, 2008). Such considerations indicate that those tool forms that are of greatest functional value, and thus the tool forms most likely to be replicated, are determined by the biometric conditions observed in a tool user's upper limb.…”

Usability Validation of an Ergonomic Inward Directional Screwdriver for Enhanced Musculoskeletal Comfort

“…The handle grip is improved by the optimum handle diameter in a way where it is easier to be secured in the hand and increases voluntary force applications. It is supported by other studies, where an optimal handle diameter increases the grip force and total normal force (Edgren et al, 2004;Kong and Lowe, 2005b;Mastalerz et al, 2009;Seo and Armstrong, 2008). At the same time, the secureness of the handle in the hand can be explained as the optimal handle diameter allowed the thumb and fingertips to work together against the palm, resulting in a greater reaction force (Seo and Armstrong, 2008).…”

“…The grip force increased with both torque directions, though the grip force for submaximal and maximal inward torques was respectively lower and higher than the grip force generated by outward torque. Besides that, the increase in handle friction (Seo et al, 2008a;2008b), increase in resistivity of handle shape towards finger phalanges segment (Kong et al, 2008) and an optimal(25-40mm) handle diameter (Edgren et al, 2004;Kong and Lowe, 2005a;Seo et al, 2007) also help in increasing the total normal force, resulting in a more stable and secure grip.…”

“…At the same time, the secureness of the handle in the hand can be explained as the optimal handle diameter allowed the thumb and fingertips to work together against the palm, resulting in a greater reaction force (Seo and Armstrong, 2008). In addition, the grip force decreases along with the increase of the handle diameter beyond the optimal diameter (Edgren et al, 2004;Kong and Lowe, 2005b;Mastalerz et al, 2009;Seo and Armstrong, 2008).…”

The Relationship Of Grip Strength With Interosseous Muscles/intermetacarpal Fat Pads Of The Hand: An Ultrasonographic Study

“…The patients were seated comfortably in a chair and were requested to grasp the dynamometer with maximum force. The grip test was performed in the standard arm position as recommended by the American Society of Hand Therapists; the shoulder adducted, elbow at 90 degrees fl exion, and forearm in neutral position (4). The patients were asked to squeeze the handle as hard as they could for 2 seconds.…”