resistance band       
noun [ C ] uk/rɪˈzɪs.təns ˌbænd/ us/rɪˈzɪs.təns ˌbænd/
 (锻炼肌肉的)阻力带,健身带,阻力橡筋带
a thick, strong ring made of rubber or a similar material, used in exercises to make the muscles stronger
  You can build up your muscles at home using dumbbells or resistance bands.  你可以在家里用哑铃或阻力带锻炼肌肉。  
Pull against a resistance band wrapped around the opposite leg. 将缠绕在另一条腿上的阻力带朝相反方向拉。 
 - More examples
 - As far as workout equipment goes, stability balls and resistance bands are two of my favourites.
 - Try the same drill but with a partner pulling against you with resistance bands attached to the waist.
 - Use free weights, resistance bands, or moves that use your own body weight to build strength.
 - These easy-to-follow workouts use resistance bands in creative and challenging ways.