EXTRA! Exercise Excess KOs Millions

Your Body's Annual Mannual

How much exercise can you handle in a year? "The answer comes down to muscle damage," says Tim Mickleborough, professor of exercise physiology at Indiana University. For example, he says, "eight weeks after completing a marathon, there's still muscle-cell regeneration going on. You haven't fully recovered, even though you might feel like you have."

Follow our guide to the number of yearly endurance tests a well-trained individual can manage and stay on the healthy side of the overtraining threshold.

EVENTNO. PER YEARR&R AFTER EVENTTIME UNTIL NEXT RACEMarathons2 per year8 weeks6 monthsHalf Marathons4 per year4 weeks3 monthsIronman Triathlons2 per year8 weeks6 monthsAdventure Races3 per year6 weeks3 monthsCentury Rides6 per year1 week2 monthsUltramarathons1 every other year8 weeksCross-train during off-year

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