• circadian effect
• swimmers
• immune system
• media

We are writing in response to the letter by Dr Webborn¹ about our circadian research on competition swimmers.² His first comment, namely that the media may wrongly slant a “take home message”, is understandable. Had he read our message more carefully, he would have seen that we noted that our observation—that there is a morning lowering of IgA and an increase in cortisol—“might not be acceptable to elite competitors”, and that we strongly qualified it by considering that early morning sessions should: “perhaps be avoided by those returning to training after injury or illness, those close to periods of important competition (which are more associated with the underperformance syndrome) and possibly those at altitude, which itself imposes a degree of immunosuppression.” All very carefully displayed in the take home message. We three authors have been involved in the preparation of elite competitors collectively for many years, and we stand by those cautionary statements.

Dr Webborn is, importantly, interested in the potential health benefits of recreational exercise to an “active population”, and makes the very valid point that trivial risks of illness, as might be investigated in elite athletes, should not deflect exercise for the vastly greater public good. However, our work was concerned with well trained competition swimmers, a point that we emphasised to the media. A major thrust of sports medicine is that it sometimes looks at clinically trivial conditions—for example, ankle or wrist sprains—which may be anything but trivial to the sports competitor. More specifically, modest levels of weekly exercise may be immuno-enhancing, whereas there is much evidence that elite levels of endurance training may be immunosuppressive,³ so one always has to be careful which message applies to whom.

In his second comment, Dr Webborn reasonably queries the hydration status of our subjects. Naturally, on working with salivary flow, we had considered this also, in terms of subject behaviour at 24, 12, and 8 hours before testing, as is indicated in our experimental design. There were no “dry mouths”.

However, overall, Dr Webborn has a possible point about media misuse of take home messages, and perhaps the editorial board could discuss this, if it is felt to be an issue.