celebs wearing the fitness trend

Sep 12, 2011 at 2:20 p.m. ET
Jessica Biel sports her fitness gear at the Revlon Walk.

1 /19: Cameron Diaz

1/19 :Cameron Diaz

2 /19: Katy Perry

2/19 :Katy Perry

3 /19: Ashley Greene

3/19 :Ashley Greene

4 /19: J Alba

4/19 :J Alba

5 /19: Fit Kardashians

5/19 :Fit Kardashians

6 /19: Feelin' bright

6/19 :Feelin' bright

7 /19: Sporty fab

7/19 :Sporty fab

8 /19: Kim K

8/19 :Kim K

9 /19: Looking fierce

9/19 :Looking fierce

10 /19: Shenae Grimes

10/19 :Shenae Grimes

11 /19: Kristin Cavallari

11/19 :Kristin Cavallari

12 /19: Elisabetta Canalis

12/19 :Elisabetta Canalis

13 /19: Matchy-matchy!

13/19 :Matchy-matchy!

14 /19: Running girl

14/19 :Running girl

15 /19: All about layers

15/19 :All about layers

16 /19: Fitness fashionista

16/19 :Fitness fashionista

17 /19: Ashley Greene

17/19 :Ashley Greene

18 /19: Reese Witherspoon

18/19 :Reese Witherspoon

19 /19: Khloe Kardashian

19/19 :Khloe Kardashian