PhotoA car seat will keep a child safer while riding in the car. But how many parents strain muscles or ligaments trying to lift these seats in and out of a vehicle?

Engineers at North Carolina State University say they have developed a new handle for infant car seats (ICSs) that makes it easier for parents to lift the seat out of a car – while retaining a firmer grip on the handle – making it less likely that the seat will be dropped.

“Many products that are designed for parents don’t take ergonomics into account, and the instructions are usually not very helpful,” said Michael Clamann, a Ph.D. student at NC State and lead author of a paper describing the research. “We wanted to see whether, by changing the angle of the ICS handle, we could make it easier on parents and safer for the baby. Our idea was that it would be easier to hold on to the seat, minimizing the risk of dropping it.”

The idea was inspired by Clamann’s experiences as a parent. His research led to a new handle design that details which angles reduce “ulnar deviation,” or how much your wrist bends, and associated pressure in the carpal tunnel. This is important in terms of lifting tasks, because the further you bend your wrist, the weaker your grip.

The team used sensors to measure muscular activity at the forearm and biceps and the wrist angle of the study participants as they lifted the ICSs with different handle designs.

Angled handle

“Our angled handle lets people better position themselves over the car seat and allowed them to use their biceps more than their forearm muscles,” Clamann said. “That’s an improvement, because our biceps are stronger than our forearms, and so are better able to bear weight. This is particularly important for smaller females lifting ICSs.”

The participants also told researchers that the angled handle design was easier to lift. The team also tested to see how foot placement – in the car or on the ground – affected the participants’ posture – and therefore their wrist angle. Such foot placement was previously recommended in the popular press literature regarding ICS handling.

“We found that placing your foot in the car to help lift the ICS allowed participants to use their biceps more and reduced how much they bent their wrists – giving them a firmer grip on the ICS,” said Kinley Taylor, an NC State graduate student and co-author of the paper. “However,” adds Clamann, “putting your foot in the car also increased the likelihood of hitting your head on the doorframe.”

The researchers plan to move forward with additional efforts to see how variations on the angled handle design affect ergonomics when used in different car designs, such as minivans, and for people who are significantly taller than the participants in this study.

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