Can infant carrier hip belts of 2-inch, 4-inch, and 6-inch dimensions influence trunk muscle activities during front infant carrying tasks?

Abstract

Background: Utilization of infant carriers (ICs) for childcare activities is common and involves varieties of hip belts to offer maximum maternal and infant support. There is a need to establish ergonomic-based guidelines for IC components as a means of improving their supportive roles. Objective: This study evaluated the effects of infant carrier (IC) hip-belt dimensions on the erector spinae (ES) and multifidus (MF) muscles of healthy adult women during front infant carrying tasks. Methods: It utilized three hip belts with different width dimensions (2 inch, 4 inch, and 6 inch) attached to the IC during three front infant carrying tasks, respectively. During each 5-min trial, the activities of the right and left components of the ES and MF muscles were simultaneously monitored via surface electromyography (EMG). Asymmetry ratios of the normalized EMG values of the right and left components of each muscle were calculated. Results: Utilization of different hip-belt dimensions did not elicit significant (p < 0.05) differences in the electrical activities of the back muscles as well as in their asymmetry ratios. However, marginal differences in the normalized EMG values showed that the 4-inch belt elicited the highest muscular activities in three of the four studied muscles. Conclusion: During simulated front infant carrying tasks, hip-belt dimensions of the ICs did not influence back muscle activities in healthy adult women. Long-term effects of IC hip-belt dimensions on back muscle activities should be evaluated in future studies.