Identifying Strategies Used to Negotiate Stairs When Carrying an Infant Surrogate
Additional Funding Sources
The project described was supported by the Ronald E. McNair Post-Baccalaureate Achievement Program through the U.S. Department of Education under Award No. P217A170273.
Presentation Date
7-2022
Abstract
For the first year of life, humans depend on caregivers to transport them. While carrying infants in arms, wraps, or carriers on a parent’s body have been used for centuries, modern infant product design has introduced alternative methods to carry infants including car seats and strollers. However, it is unclear how these different carrying methods may impact a caregiver’s biomechanics or risks of injury. The objective of this study is to identify strategies used when negotiating stairs with a 12 pound infant manikin.
An outdoor obstacle course was designed, representing typical activities required to navigate urban architecture: ascending and descending stairs and ramps, entering and exiting buildings, and crossing curbs. The course was completed by ten healthy female participants (aged 21-24 years). A pre-testing questionnaire was completed by each participant to screen out potential participants who were mothers or who had current injuries and/or pain. All participants were injury and pain free. No participant was a mother or had been previously pregnant. Participants carried an infant manikin in a carrier, car seat, stroller, and in arms through the urban obstacle course. Each carrying method was completed six times, three times forward and three times backwards through the course. High-speed video cameras filmed each obstacle along the course. This abstract focuses only on the stair obstacle.
Three investigators watched fifty randomly selected trials and identified them. A total of 240 trials were collected. Six trials had to be excluded due to equipment malfunctions. The breakdown of device conditions of the remaining 234 trials were 59 in arms, 59 in a carrier, 60 in a car seat, and 56 in a stroller. Investigators watched 50 random trials and denoted movement strategies for each carrying condition based on defining characteristics.
When carrying the infant manikin in arms four main strategies were observed; carrying on the hip with a single arm (dominant or non-dominant) with and without support from the second arm. When walking with the manikin in a baby carrier three main strategies were observed: arms hanging freely, arms wrapped around the carrier providing additional support, and arms resting on the carrier providing little to no support. Six strategies were identified in the car seat condition: carrying the car seat at the elbow (dominant and nondominant) with and without support from the second arm (support), a mixed grip, and a single arm “lock” grip. Five strategies were identified in the stroller condition: a forward push, a backwards pull, a front wheel pop, carrying, and a step by step carry. A “switch” and an “other” category were added to each condition for cases when a participant transferred between strategies or used a strategy not defined above.
The most commonly employed strategy across all conditions was free hanging arms when the manikin was in a carrier. Free arms were seen in 45.8% of trials in the carrier condition. In the in arms condition the single arm (dominant) + support was the most commonly employed strategy accounting for 44.1% of all in arms trials. The most common strategy for carrying the car seat was carrying at the elbow (dominant) + support, which was observed in 25% of the car seat trials. Carrying the stroller was the most common strategy implemented in the stroller condition, and accounted for 35.7% of stroller trials.
There was more variability in the strategies chosen for the car seat and stroller conditions than the in arms or carrier conditions during stair negotiation. This may be attributed to a relative lack of infant care experience in the participants. The car seat and stroller were also the bulkiest carrying devices which may have increased carrying difficulty. This may have contributed to participants changing between carrying strategies across trials and within trials. Greater consistency may be seen in future studies conducted on mothers and other primary caregivers of infants.
Identifying Strategies Used to Negotiate Stairs When Carrying an Infant Surrogate
For the first year of life, humans depend on caregivers to transport them. While carrying infants in arms, wraps, or carriers on a parent’s body have been used for centuries, modern infant product design has introduced alternative methods to carry infants including car seats and strollers. However, it is unclear how these different carrying methods may impact a caregiver’s biomechanics or risks of injury. The objective of this study is to identify strategies used when negotiating stairs with a 12 pound infant manikin.
An outdoor obstacle course was designed, representing typical activities required to navigate urban architecture: ascending and descending stairs and ramps, entering and exiting buildings, and crossing curbs. The course was completed by ten healthy female participants (aged 21-24 years). A pre-testing questionnaire was completed by each participant to screen out potential participants who were mothers or who had current injuries and/or pain. All participants were injury and pain free. No participant was a mother or had been previously pregnant. Participants carried an infant manikin in a carrier, car seat, stroller, and in arms through the urban obstacle course. Each carrying method was completed six times, three times forward and three times backwards through the course. High-speed video cameras filmed each obstacle along the course. This abstract focuses only on the stair obstacle.
Three investigators watched fifty randomly selected trials and identified them. A total of 240 trials were collected. Six trials had to be excluded due to equipment malfunctions. The breakdown of device conditions of the remaining 234 trials were 59 in arms, 59 in a carrier, 60 in a car seat, and 56 in a stroller. Investigators watched 50 random trials and denoted movement strategies for each carrying condition based on defining characteristics.
When carrying the infant manikin in arms four main strategies were observed; carrying on the hip with a single arm (dominant or non-dominant) with and without support from the second arm. When walking with the manikin in a baby carrier three main strategies were observed: arms hanging freely, arms wrapped around the carrier providing additional support, and arms resting on the carrier providing little to no support. Six strategies were identified in the car seat condition: carrying the car seat at the elbow (dominant and nondominant) with and without support from the second arm (support), a mixed grip, and a single arm “lock” grip. Five strategies were identified in the stroller condition: a forward push, a backwards pull, a front wheel pop, carrying, and a step by step carry. A “switch” and an “other” category were added to each condition for cases when a participant transferred between strategies or used a strategy not defined above.
The most commonly employed strategy across all conditions was free hanging arms when the manikin was in a carrier. Free arms were seen in 45.8% of trials in the carrier condition. In the in arms condition the single arm (dominant) + support was the most commonly employed strategy accounting for 44.1% of all in arms trials. The most common strategy for carrying the car seat was carrying at the elbow (dominant) + support, which was observed in 25% of the car seat trials. Carrying the stroller was the most common strategy implemented in the stroller condition, and accounted for 35.7% of stroller trials.
There was more variability in the strategies chosen for the car seat and stroller conditions than the in arms or carrier conditions during stair negotiation. This may be attributed to a relative lack of infant care experience in the participants. The car seat and stroller were also the bulkiest carrying devices which may have increased carrying difficulty. This may have contributed to participants changing between carrying strategies across trials and within trials. Greater consistency may be seen in future studies conducted on mothers and other primary caregivers of infants.