Research Review: Eyes on the ball

More than two-thirds of adults experience low back pain (LBP) at some point in their lives. It is also commonly thought that LBP is more prevalent in individuals who sit for prolonged periods.

More than two-thirds of adults experience low back pain (LBP) at some point in their lives. It is also commonly thought that LBP is more prevalent in individuals who sit for prolonged periods. This is significant, as approximately 75 per cent of workers in industrialized nations are required to sit for prolonged periods at work, with this rate continually increasing worldwide.

It has been suggested that by replacing traditional office chairs with stability balls, we could potentially solve (or at least mitigate) this problem. It is also thought this approach may help increase core strength, improve posture, and/or improve spinal motion, which may help improve LBP.

The purpose of this study was to investigate whether sitting on a stability ball, instead of a chair would have an effect on core endurance, nonspecific LBP, and/or disability as a result of LBP.

Study methods
This was an experimental, cross-over, randomized study conducted in a university setting. Subjects were recruited through a campus-wide email and flyer campaign and had to meet the following inclusion criteria: self-reported sitting an average of four hours/day, five days/week; university students, faculty members, or staff of the university; aged 18 to 65 years.

Exclusion criteria included: back symptoms with radiation distal to the knee; pregnancy; obvious balance deficits; weight exceeding the 600-lb. limit of the stability ball.
Subjects were randomly assigned to either the intervention group or the control group for an eight-week session. At the end of the first eight-week period, the original control group received the intervention and the intervention group became the control group for an additional eight weeks. Researchers and subjects were
not blinded.

Baseline data collected included the Oswestry Disability Index (ODI), an 11-point numeric pain rating scale (NPRS), and core endurance test scores. This data was collected again after each eight-week period. Additionally, NPRS and adverse event data were collected weekly via online surveys.

The core endurance tests utilized included: Isometric Trunk Flexion, Side Plank, Sorensen Test.

The intervention group was asked to replace their chair with an assigned stability ball each day for five days per week, starting at 56 minutes per day in week 1, and increasing by 10 per cent per week until week 6. At this point, they were sitting on the ball for 90 minutes a day. This length was maintained through weeks 7 and 8. The ball assigned was the correct size to allow the subject’s hips and knees to stay at approximately 90 degrees with both feet flat on the floor and at a comfortable height for typing and writing. The control group was asked to continue using their regular office chair.

Results
Ninety subjects were included in this study. No statistically significant changes in LBP or disability were found between the control and intervention groups and no statistically or clinically significant changes were seen in ODI and NPRS scores.

Although the changes were not significant, it was noted that almost a quarter of chair-sitters showed an increase in ODI scores over the eight weeks, while only 14.5 per cent of ball-sitters showed similar increases.

The ball-sitting group showed statistically significant increases in isometric trunk flexion and Sorensen endurance scores but not in side plank measurements. This may indicate that ball-sitting targets the dorsal and ventral core muscles rather than the (more lateral) oblique abdominals.

Clinical application, conclusions
Sitting on a stability ball seems to improve sagittal plane core endurance but did not appear to prevent, increase or decrease LBP or disability. Further research should incorporate longer periods of ball-sitting or perhaps even complete replacement of the office chair in order to better-study this intervention.

Dr. Shawn Thistle is the founder and CEO of RRS Education (rrseducation.com), which helps busy clinicians integrate current research evidence rationally into practice. He also maintains a practice in Toronto, lectures at CMCC and provides chiropractic medicolegal consulting services. Reach him at: shawn@rrseducation.com