Table 3.
Quality assessment for risk of bias of the included studies using the criteria recommended by the Cochrane back review group
| Study | Selection bias | Performance bias | Attrition bias | Reporting bias | Study-specific | Total score (maximum 7) | ||
|---|---|---|---|---|---|---|---|---|
| Similar baseline characteristics | Acceptable compliance | Acceptable and described drop-out rate | No selective outcome reporting | Similar timing of outcome assessment | Training status reported | Smoking status reported | ||
| Asami et al. [36]a | Unsure | Yes | No | Yes | Yes | No | Yes | 4 |
| Bloomer et al. [59] | Yes | Yes | Yes | Yes | Yes | Yes | Yes | 7 |
| Briviba et al. [49] | No | Yes | Yes | Yes | Yes | No | No | 4 |
| Davison et al. [65] | Yes | Yes | Yes | Yes | Yes | No | Yes | 6 |
| Fogarty et al. [67] | Yes | Yes | Yes | Yes | Yes | Yes | Yes | 7 |
| Fogarty et al. [66] | Yes | Yes | Yes | Yes | Yes | No | No | 5 |
| Harms-Ringdahl et al. [50] | No | Yes | Yes | Yes | Yes | No | Yes | 5 |
| Hartmann et al. [70] | No | Yes | Yes | Yes | Yes | Yes | Yes | 6 |
| Hartmann et al. [68] | Yes | Yes | Yes | Yes | Yes | No | Yes | 6 |
| Hartmann et al. [69] | No | Yes | Yes | Yes | Yes | Yes | Yes | 6 |
| Inoue et al. [56] | No | Yes | Yes | Yes | Yes | Yes | Yes | 6 |
| Itoh et al. [60] | Yes | Yes | Yes | Yes | Yes | Yes | Yes | 7 |
| Kim et al. [79] | Yes | Yes | Yes | Yes | Yes | Yes | Yes | 7 |
| Liu et al. [38] | Yes | Yes | Yes | Yes | Yes | No | Yes | 6 |
| Mastaloudis et al. [51] | No | Yes | Yes | Yes | Yes | No | Yes | 5 |
| Meihua et al. [58] | Yes | Yes | Yes | Yes | Yes | No | Yes | 6 |
| Møller et al. [34] | No | Yes | Yes | Yes | Yes | No | No | 4 |
| Niess et al. [39] | Yes | Yes | Yes | Yes | Yes | Yes | No | 6 |
| Niess et al. [71] | Yes | Yes | Yes | Yes | Yes | Yes | No | 6 |
| Orlando et al. [48]a | Yes | Yes | Yes | No | Yes | Yes | No | 5 |
| Paik et al. [72] | Yes | Yes | Yes | Yes | Yes | No | No | 5 |
| Peters et al. [73] | Yes | No | No | Yes | Yes | Yes | No | 4 |
| Pittaluga et al. [53] | Yes | Yes | Yes | Yes | Yes | Yes | Yes | 7 |
| Revan [61] | Yes | Yes | Yes | Yes | Yes | Yes | Yes | 7 |
| Roh et al. [37]a | Yes | Yes | Yes | Yes | Yes | Yes | Yes | 7 |
| Ryu et al. [40] | Yes | Yes | Yes | Yes | Yes | Yes | Yes | 7 |
| Sacheck et al. [62] | No | Yes | Yes | Yes | Yes | Yes | Yes | 6 |
| Sardas et al. [55] | Yes | Yes | Yes | Yes | Yes | Yes | Yes | 7 |
| Saritaş et al. [63] | Yes | Yes | Yes | Yes | Yes | No | Yes | 6 |
| Sato et al. [64] | Yes | Yes | Yes | Yes | Yes | Yes | Yes | 7 |
| Shi et al. [57] | Yes | Yes | Yes | Yes | Yes | Yes | Yes | 7 |
| Tanimura et al. [74] | Yes | Yes | Yes | Yes | Yes | No | Yes | 6 |
| Tanimura et al. [54] | No | Yes | Yes | Yes | Yes | Yes | Yes | 6 |
| Tsai et al. [75] | Yes | Yes | Yes | Yes | Yes | No | No | 5 |
| Turner et al. [76] | Yes | No | No | Yes | Yes | No | Yes | 4 |
| Wagner et al. [77] | Yes | Yes | Yes | Yes | Yes | Yes | No | 6 |
| Williamson et al. [80] | Yes | Yes | Yes | Yes | Yes | Yes | Yes | 7 |
| Zhang et al. [78] | Yes | Yes | Yes | Yes | Yes | Yes | Yes | 7 |
aNot included in meta-analyses