Table 1 Quality assessment summary (see Additional files  2  and  5  for item decision rules and scores for each included study)
| Â | Quality assessment domains | Percentage of studies scoring yes |
|---|---|---|
| Â | Selection bias | Â |
1. | Was the study population adequately described? | 57% |
2. | Where both groups drawn from the same population? | 39% |
3. | Were both groups comparable for age, sex, BMI/weight | 54% |
4. | Was pain intensity and/or activity limitation described for LBP group? | 56% |
5. | Was an attempt made to define back pain characteristics? | 34% |
| Â | Measurement and outcome bias | Â |
6. | Did the method description enable accurate replication of the measurement procedures | 90% |
7. | Was the measurement instrument adequately described? | 95% |
8. | Was a system for standardising movement instructions reported? | 37% |
9. | Were assessors trained in standardised measurement procedure? | 2% |
10. | Did the same assessors test those with and without back pain | 17% |
11. | Were assessors blinded as to which group subjects were in? | 0% |
12. | Was the same assessment procedure applied to those with and without back pain? | 93% |
| Â | Data presentation | Â |
13. | Were between-group statistical comparisons reported for at least one key outcome | 94% |