Response

Extract

We thank Zhang et al. for their comment and dose–response meta-analysis in response to our review ( 1 ). Their analysis provides some interesting data to suggest that the dose–response relationship between physical activity and the risk of colon cancer may differ slightly by subsite and a full systematic review and dose–response meta-analysis of this topic would be a valuable addition to the literature. However, we would suggest that Zhang and colleagues’ analysis of increasing amounts of metabolic-equivalent (MET) hours per week is assessing the impact of volume (or dose) of total physical activity (ie, frequency × duration × intensity), rather than intensity, on the risks of proximal and distal colon cancers. As noted in Barton ( 2 ), the same level of MET hours per week can be achieved by performing vigorous-intensity physical activity for a short time, moderate-intensity physical activity for a relatively longer period, or a combination of vigorous- and moderate-intensity physical activity.