You don’t need expensive weight machines or free weights to increase strength because elastic bands work just as well.
Researchers from Malaysia and Australia found that muscle activation was greater when doing biceps curls with elastic bands compared to free-weight dumbbells.
The elastic bands worked best when shortened by 30 percent, which increased resistance.
Elastic bands are inexpensive, lightweight and portable, and can be used almost anywhere to provide a quality resistance exercise workout. (European Journal Sport Science. 13: 155-163. 2013)