I found the historical information in the article “Effect of rosary prayer and yoga mantras on autonomic cardiovascular rhythms: comparative study” as well as the information on rhythmic breathing to be helpful. Bernardi et al. (2001) described how recitation of the rosary (a repetitive Roman Catholic prayer) and yoga mantras slow respiration to a specific rhythm which can benefit heart rate and blood pressure. While, the effects of meditative practices such as yoga have been more widely studied repetitive and meditative prayer have not been studied as much. This paper was able to investigate a slight historical link between the two practices as well as a possible hypothesis for why both practices may be of physiological benefit to practitioners.
Bernardi, L., Sleight, P., Bandinelli, G., Cencetti, S., Fattorini, L., Wdowczyc-Szulc, J., & Lagi, A. (2001). Effect of rosary prayer and yoga mantras on autonomic cardiovascular rhythms: comparative study. Bmj, 323(7327), 1446-1449.