Experimental design to evaluate the influence of anthropometric factors on the grip force and hand force exertion

• The hand force exertion was measured using the Borg Category Ratio (CR10) scale.
• Effects of gender, hand dominance, smoking status, hand positions and wrist positions under the two Borg scales were investigated.
• A regression model to quantify the grip force based on different anthropometric factors was conducted.
• The endurance time and the maximum voluntary contraction were quantified based on different factors.

Many industrial operations require gripping of tools. Therefore, it is essential to determine the grip force for labors (i.e. operators). Ratings of perceived exertion is an indirect measure method of the grip force. It is an efficient and low cost method. This method is convenient for large sample numbers as well. In this study, a Borg Category Ratio (CR10) scale is used to measure and estimate the exertion in a physical oriented way. Forty six subjects were evaluated on two scales (i.e. levels) of the CR10 scale (2 and 10 CR10 scales) under different positions. This study also investigates the effect of gender, smoking status, hand dominance, hand positions (90° and 180°) and wrist positions (45° flexion, and 45° extension) under the two Borg scales. The grip force between males and females was significant at both CR10 scale levels. The grip force was neglected between the dominant and the non-dominant hands when level 2 of CR10 was used. Moreover, the grip force was significantly different between the two positions of the hand (90° and 180°) at Borg scale level 10. Conversely, the grip force was not significantly different between the two hand positions at level 2. Same results were found for the wrist positions (45° flexion and 45° extension). The mean force at 45° extension position is greater than that at 45° flexion position. Three regression models were conducted for the purpose of this study. The first regression model was conducted to quantify the grip force for males and females based on hand dominance, hand positions, wrist positions, and CR10 scale. The second regression model was also conducted to predict the Maximum Voluntary Contraction (MVC) value based on gender, age, smoking status, hand dominance, hand length, hand breadth and Body Mass Index (BMI). The third regression model was conducted to estimate the endurance time value based on gender, smoking status, hand dominance, hand position, wrist position, Borg scale exertion, and MVC. Significant R2 values were shown by the regression models.