Using a stability ball as an office chair strengthens core muscles, similar to the use of a backless chair or stool; the freedom of movement from a stability ball also may decrease confined or constrained body postures that frequently occur at workstations.
Additionally, a study by Indiana University ergonomics experts found that reaching with the non-dominant hand results in different firing patterns in leg musculature compared to reaching with the dominant hand.
"It's a learning effect. When you use your dominant hand, your firing patterns are more established, even in the lower body, to stabilize the movement. Interestingly, when reaching with the non-dominant hand, muscle recruitment appears to be different," said Kelly Jo Baute, a researcher in the Indiana Ergonomics lab in Indiana University's School of Health, Physical Education and Recreation.
Baute and her colleagues at Indiana Ergonomics investigated the effects that performing a common reaching task had on muscle activity in the legs while sitting on a stability ball. They found that the greatest muscle activity was located in the anterior tibialis (shin muscle) which acted in coordination with the hamstrings muscles to provide a stable foundation during the reaching movements.
The study involved nine men ages 23-29 who performed a reaching task while sitting on a stability ball at a work station. The task involved picking up a cup of water and moving it either away from to closer to the body. EMG activity was measured in the quadriceps, hamstrings, anterior tibialis and gastrocnemious muscles in the legs. EMG activity was measured for muscle contraction onset, duration and intensity. The study found that the duration of the hamstring contraction and the onset of the anterior tibialis had the highest effect size when the study participants reached with the non-dominant hand.
Besides giving the lower body an opportunity to learn some new skills, the use of a stability ball at a work station can let workers move in a more free or natural manner, potentially reducing the risk of musculoskeletal disorders that can lead to low back pain often caused by sitting in the same position for long periods of time. Baute cautions against spending too much time on the ball, however, suggesting employees gradually increasing the amount of time they use it.
"Using a ball is going to cause people to use a little more muscle recruitment to stabilize themselves when they're moving," she said. "It also gets them out of confined postures."
The study was supported by the School of HPER graduate research grant in-aid scholarship. Co-authors are Bill Wyatt, Eric Holten, Allison Berger, and John Shea, all with the Indiana Ergonomics lab in the Department of Kinesiology; and Fernando Ona, Department of Applied Health Science.
Baute will make her presentation on Sunday, Nov. 8, at 4:30 p.m. in Hall A-B of the Philadelphia Conference Center.
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