Kendo masters, archery and blood flow: Tanaka 2004

The study measures how the small vessels in the fingertips respond in 35 healthy men sitting at rest: 7 kendo masters (fifth dan or above, mean age 43.7, around thirty years of practice), 7 university kendo athletes, 7 university kyudo archers, 5 karateka and 9 sedentary office workers (mean age 45.8). The measure is the height of the P wave of the differentiated digital pulse, expressed as a percentage of the starting value.

When the right arm was raised the wave grew most in the kendo masters, up to 250.0% (standard deviation 53.1), significantly more than in kyudo and karate; the lowest value was in the karateka, 138.8%. With the left arm the masters reached 233.0% and the kyudo archers 137.3%, again a significant difference. When the arm was lowered the wave fell in everyone, most in the masters (28.4% on the right) and least in the karateka (42.0%), with no significant differences between groups.

Imagining a tense scene for one minute reduced the wave in every group, meaning the vessels narrowed. The effect was strongest in the kyudo archers, who dropped to 49.6%, and weakest in the kendo masters (77.1%); the difference between kyudo and both the masters and the office workers was significant. With a relaxing scene only the masters showed an increase (107.1%), a sign of dilation; the office workers (87.6%), university kendo athletes (86.0%) and kyudo archers (77.6%) stayed significantly below their starting value.

Measurements were taken seated, in a room at 24 degrees. The fingertip signal came from a calibrated transmitted-light plethysmograph (Nihon Kohden MLV-2201) and was differentiated electronically (time constant 0.03 seconds): the height of the P wave of this derivative depends on how fast the pulse rises and reflects the tone of the small vessels. An electrocardiogram, instantaneous heart rate and breathing, recorded with a thermistor, were used to check that the rest of the body stayed stable.

In the position test the fingertip started at heart level and was raised about 90 degrees above it or lowered about 90 degrees below it. In the imagery test the left hand stayed at heart level and the participant recalled, for one minute, a scene of tension or pressure, then a pleasant one; afterwards they described what they had imagined. The martial artists mostly chose waiting for their turn at a grading or the moments before a bout, the office workers a complaining customer or a scolding from the boss; the relaxing scenes were nature, hot springs, bed, family. A new condition began only once the effect of the previous one had faded. Groups were compared with one-way analysis of variance and the Tukey-Kramer test. The students in each discipline belonged to university clubs and trained at least five days a week.

The groups are small, 5 to 9 people, all men, and each was measured only once: there is no way to tell whether the differences come from practice, from age or from who chooses a given discipline. The comparison that concerns archers is the weakest, because the kyudo practitioners are students in their twenties and the kendo masters are men over forty with thirty years of practice: discipline, age and experience are mixed together.

What the participants imagined was left to them and varied from person to person, and how vividly they imagined it, asked at the end of the test, is not reported in the results. Tables 2 and 3 in the PDF are images from which the numbers cannot be extracted: this page uses the values given in the text. That the strong kyudo response reflects the tension typical of aiming sports, or that the sustained load of the fingers on the string changes the vessels, are the authors' hypotheses and are not tested here. Finally, nobody shot: the study measures the fingers at rest, not during shooting, and has no performance data. The paper is in Japanese, with an English abstract.

For an archer only one finding matters: in seven young kyudo practitioners, imagining a pressure situation for a minute was enough to narrow the finger vessels markedly, and even a pleasant scene did not bring them back to baseline, whereas kendo masters with decades of practice reacted much less. It shows that imagining a competition situation has a measurable effect on the body, even when sitting down with no bow in hand.

It does not allow anyone to say that kyudo makes people more tense, that colder hands make shooting worse, or that any particular imagery practice helps. The number of archers is far too small and no measurement concerns shooting.