Risk of bias assessment
| Study | Potential risk of bias item | Risk of bias | |||||
| 1 | 2 | 3 | 4 | 5 | 6 | ||
| Bengtsson et al (2013)7 | + | − | + | + | − | + | High |
| Brooks and Kemp (2011)10 | + | − | + | + | − | + | High |
| Hägglund et al (2013)8 | + | + | + | + | − | + | Low |
| Orchard (2001)6 | + | − | + | + | + | + | Low |
| Carling et al (2015)14 | − | + | − | + | + | + | High |
| Nilstad et al (2014)23 | + | + | − | + | + | + | Low |
| McKay et al (2001)25 | − | + | − | − | − | + | High |
| Faude et al (2006)22 | + | − | + | + | − | + | High |
| Korkia et al (1994)13 | − | − | − | − | − | − | High |
| Gabbett and Domrow (2007)24 | + | − | + | + | + | − | High |