Research Review By Dr. Ceara Higgins©

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Date Posted:

January 2017

Study Title:

The effect of sitting on stability balls on nonspecific lower back pain, disability, and core endurance

Authors:

Elliott TLP, Marshall KS, Lake DA, et al.

Author's Affiliations:

Armstrong State University, Savannah GA; Dekalb Medical, Atlanta, GA; Coastal Therapy, Savannah, GA; Gundersen Sports Medicine Center, LaCrosse, WI, USA.

Publication Information:

Spine 2016; 42(18): E1074-E1080.

Background Information:

More than 2/3 of adults experience low back pain (LBP) at some point in their lives, with 12-44% experiencing LPB at any given time (2). It is also commonly thought that LBP is more prevalent in individuals who sit for prolonged periods (3). This is significant, as approximately 75% of workers in industrialized nations are required to sit for prolonged periods at work, with this rate continually increasing worldwide (1). 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 (4).

The purpose of this study was to investigate whether sitting on a stability ball, instead of a chair, for up to 90 minutes per day, over an 8-week period, would have an effect on core endurance, nonspecific LBP, and/or disability as a result of LBP.

Pertinent Results:

90 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 that almost a quarter of chair-sitters showed an increase in ODI scores over the eight weeks, while only 14.5% of ball-sitters showed similar increases.

The ball-sitting group showed statistically significant increases in isometric trunk flexion and Sorenson 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.

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 4hours/day, 5 days/week
  • University students, faculty members, or staff of the university
  • Aged 18 to 65 years
Exclusion Criteria:
  • Back symptoms with radiation distal to the knee
  • Pregnancy
  • Obvious balance deficits
  • Weight exceeding the 600-pound limit of the stability balls
Subjects were randomly assigned to either the intervention group or the control group for an 8-week session. At the end of the first 8-week period, the original control group received the intervention and the intervention group became to control group for an additional 8 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 8-week period. Additionally, NPRS and adverse event data were collected weekly via online surveys.

The core endurance tests utilized included the following:
  1. Isometric Trunk Flexion: Subjects started seated on the table with their hips and knees bent and their back supported at approximately a 55-degree angle. Their feet were secured with a canvas strap and the subject was asked to engage their abdominal muscles and lift their back away from the table. Subjects then maintained the trunk flexion angle (55-60 degrees) for as long as possible. The test was ended if their back dropped back into contact with the table.
  2. Side Plank: Subjects began side lying on their dominant side, supported on their bottom elbow, placed directly under their shoulder. Next, they placed one foot on top of the other and lifted their hips off the table. Subjects were asked to try and keep their body in a straight line by engaging their abdominal muscles. The plank was then repeated on the non-dominant side. The test was ended and time recorded if the subject’s hips raised or dropped > 50% from the original distance from the table.
  3. Sorensen Test: Subjects were asked to lay on their stomach and slide their upper body off the table until the top of their pelvis was at the edge of the table. The lower extremities were strapped down with canvas straps over the hamstrings and lower calves. Subjects were then asked to place their hands behind their head and hold their upper body parallel to the floor. The test ended and the time was recorded when the subject’s chest dropped by 5 or more inches.
The intervention group was asked to replace their chair with an assigned stability ball each day for 5 days/week, starting at 56 min/day in week 1 and increasing by 10% per week until week 6. At this point, they were sitting on the ball for 90 min/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.

Study Strengths / Weaknesses:

Strengths:
  • This study is somewhat more generalizable than other studies, due to the increased duration of sitting, use of the ball in the home or work environment, and the larger sample size (n = 90).
Weaknesses:
  • Compliance with the intervention may have been be an issue as participants self-reported.
  • The use of a convenience sample may make the results less generalizable.
  • The length of time spent sitting on the ball may still not have been long enough to see any differences.

Additional References:

  1. Balague F, Mannion AF, Pellise F, et al. Non-specific low back pain. Lancet 2012; 379: 482-491.
  2. Koes B, Tulder M. Acute low back pain. Am Fam Physician 2006; 74: 803-805.
  3. Janwantanakul P, Pensri P, Jiamjarasrangsri W, et al. Prevalence of self-reported musculoskeletal symptoms among office workers. Occup Med Oxf Engl 2008; 58: 436-438.
  4. Kingma I, van Dieen JH. Static and dynamic postural loadings during computer work in females: sitting on an office chair versus sitting on an exercise ball. Appl Ergon 2009; 40: 199-205.