Carol's pick:
Luciano Bernardi, Peter Sleight, etc. Effect of rosary prayer and yoga mantras on autonomic cardiovascular rhythms: comparitive study.

The above study is a bit to wade through, but has fascinating observations on the origin of rosary prayer and the effect of both rosary recitation and mantra recitation on heart rhythm. The link should take you to the complete article rather than the abstract, but there is a lot of white space between the headline and the body of text.