Ask a PT Response: "There are a multiple number of studies which reference the use of resistance bands vs. free weights ie: http://search.medscape.com/medline-search?newSearch=0&queryText=resistance+band+strengthening - http://search.medscape.com/medline-search?newSearch=0&queryText=resistance+band+strengthening +
http://vsearch.nlm.nih.gov/vivisimo/cgi-bin/query-meta?v%3Aproject=medlineplus&query=resistance+band+training&x=99&y=14 - http://vsearch.nlm.nih.gov/vivisimo/cgi-bin/query-meta?v%3Aproject=medlineplus&query=resistance+band+training&x=99&y=14
http://ajs.sagepub.com/search?fulltext=resistance+band+training&submit=yes&x=22&y=13 - http://ajs.sagepub.com/search?fulltext=resistance+band+training&submit=yes&x=22&y=13
http://search.pedro.org.au/pedro/recordlist.php?abstract_with_title=resistance+band+training&Therapy=&authors_association=&Problem=&Title=&Body_part=&Source=&Subdiscipline=&Year_of_publication=&Method=&Date_record_was_created=&NScore=&-lop=and&-max=20&-find=Start+Search&-find - http://search.pedro.org.au/pedro/recordlist.php?abstract_with_title=resistance+band+training&Therapy=&authors_association=&Problem=&Title=&Body_part=&Source=&Subdiscipline=&Year_of_publication=&Method=&Date_record_was_created=&NScore=&-lop=and&-max=20&-find=Start+Search&-find =

Basically the benefits for strengthening with resistance bands are:
1) ease of use and portability
2) fairly inexpensive
3) allows for complete freedom of motion as it can be adjusted for any individual and for any position
4) works not only the intended muscle(s) but smaller stabilizing muscle(s) as well
5) able to simulate both functional and sport related movements when training
6) allows user to develop strength throughout the range of motion compared to free weights
I hope this helps."