I am a 30-year-old woman training for a triathlon with running, biking, and swimming. I notice in sprint training that sometimes I'm really on and others I'm just sluggish. Is my age already starting to wear me down?

From a physiologic point-of-view you have already peaked by age 30 but many athletes have proven it's possible to keep going and do quite well. Your age may not be as much of a factor as your gender. Women are known to have increased or decreased peak power output based on their menstrual cycles.

Researchers have shown that maximum sprint performance varies throughout the month. During the luteal phase (after ovulation) peak muscle power may be lower than the follicular phase (before ovulation). These results are based on women with normal, regular menstrual cycles.

Many female athletes are amenorrhea. This means they stop having a menstrual period. High, intensity training that burns body fat often triggers this protective response in females. If you are still having regular periods, chart your training response for the next three months along with your menstrual cycle. See if there are any links between the two.