Crossing time zones ups athlete illnesses

One of the reasons British athletes are doing so well at the London Summer Olympics may be they did not have to travel across time zones, researchers say. Martin Schwellnus of the University of Cape Town in South Africa and colleagues tracked the daily health of 259 elite rugby players competing in the 2010 Super 14 Rugby Tournament -- 14 teams from Australia, South Africa and New Zealand compete during 16 weeks -- February to May -- at venues in all three countries, and in time zones varying from 2 to 11 hours' difference from their own. Games are played weekly to a high intensity international standard, accompanied by three to five weekly training sessions over the 16-week period. The eight team physicians completed a daily log of any illness that required medical attention for each member of their squad. The rate of illness was calculated for 1,000 player days, with the total number of player days across all the teams 22,676, based on squad size times the days of play. The team doctors reported 469 illnesses in 187 of the players giving an overall incidence of just under 21 per 1,000 player days. The study, published in the British Journal of Sports Medicine, found for matches played on home turf before international travel, the incidence was 15.4 illnesses/per 1,000 player days, but this rose to 32.6/1,000 player days for matches played in locations that were 5 or more hours' time difference away from home, irrespective of direction of travel.