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Heidi Workout

"Even a day at the beach can turn into a #fun #fitness day. #ThrowbackThursday w/ " @HeidiKlum #tbt"

Heidi Klum's 5-Day Fitness Routine

From running to circuit training, Twitter photos of Heidi Klum's workout routine began streaming in last Thursday with the hashtag #HKNB as part of her New Balance collaboration. Check out these inspiring sporty snapshots to find out some of the supermodel's body secrets. -- By Erin Kim