In one study, members of the Japanese Olympic team were divided into an acupuncture group and a control group. The acupuncture group, which was given daily treatment, had a decreased maximum heart rate during training, and a statistically significant increase in maximum oxygen consumption of 13%. No such changes occured in the control group.

Yim M-1 1987 Acupuncture: preliminary report of its role as a stimulus for cardiorespiratory enhancement in swimmers. Medicine and Sport Science 24:23-29