doi: 10.1017/S1368980012004466. Published by Cambridge University Press 19 October 2012

We regret to announce that there are mistakes in some citations under the section Cardiorespiratory fitness in the Method (Page 2). These corrections do not affect any other part of the article.

Cardiorespiratory fitness

Cardiorespiratory fitness was assessed using the 20m shuttle-run test (20mSRT) administered in the form of the FITNESSGRAM PACER, a modified version of the original protocol^{(22 not 21) (Leger et al. 1988)}. Participants had previously taken part in the 20mSRT as part of their physical education. Participants were encouraged by both the instructions on the PACER CD and a researcher to ‘run for as long as possible’. The test requires volunteers to run back and forth over a marked distance of 20 m in time with an audible signal. The test starts at an initial running speed of 8.0 km/h and increases initially by 1 km/h after the first minute and then by 0.5 km/h each minute thereafter. Researchers acted as ‘spotters’ and recorded the final shuttle count at either the point of volitional exhaustion or when the participant failed to maintain the required running speed twice. Final shuttle count was converted first to final running speed and then into Z-scores based on global performance indices^{(21 not 22) (Olds et al. 2006)}. VO_2max (ml/kg per min) was predicted based on final running speed and age^{(22 not 23) (Leger et al. 1988)}. FITNESSGRAM PACER Healthy Fitness Zone cut-offs^{(23 not 20) (Meredith & Welk 2007)} were used to categorize participants. If participants’ total completed shuttle count was above their age- and sex-specific cut-off, they were classed as ‘fit’; otherwise they were classified as ‘unfit’.