MILWAUKEE (AP) -

More than 4,500 of the country's top amateur triathletes will be in Milwaukee this weekend.

The 2013 USA Triathlon Age Group Nationals is being held on the lakefront on Saturday and Sunday.

The triathletes are competing in Olympic-Distance and Sprint National Championships with national titles and spots on Team USA for the 2014 ITU World Championships in Edmonton, Canada.

National titles will be up for grabs in 28 age groups. The Olympic-distance age group event consists of a 1.5-kilometer swim, 40-kilometer bike and 10-kilometer run course. The sprint event has a 750m swim, a 20k bike and a 5k run.

Four-time Ironman World Champion Chrissie Wellington is expected to be in attendance at the races.

VISIT Milwaukee estimates the local economic impact at $2.3 million.