Anyone who has shot for a few years knows their string fingers well. The pads of the index and middle fingers harden, sometimes a callus forms that you can feel to the touch, and after a long day of arrows the fingers may tingle or ache for a few hours. Kyudo archers know another callus too, on the bow hand at the base of the thumb. The question I am asked is always the same: are these the normal adaptations of someone who shoots a lot, or signs of something worth looking at?
The studies that have looked at archers' hands are few and small, and they answer in pieces. On the skin of the fingertip there is one measurement of eight archers; on the bow-hand callus, an examination of thirty kyudo practitioners carried out in 1971; on the small vessels of the fingers, a single case report and a kyudo study that does not separate the string hand from the other. Then there is the acute side, the cuts and knocks, where the numbers are large but the people counted are very different from those who shoot in competition. Finger dexterity and grip strength have a page of their own, on dexterity and grip in archers; here I stay with the skin, the vessels and the injuries.
The skin of the fingertip
The only measurement of the skin on the string fingers comes from a Japanese laboratory, in 2007. There were eight archers, all university students with one to three years of practice, and they were compared with six students who did not shoot. With a durometer, the instrument that measures how much a surface gives under pressure, the index fingertip of the string hand turned out harder in the archers: 49.3 against 39.8 on the instrument's scale. It is the simplest finding in the whole picture, and it points the same way as what every archer feels when touching their fingers, namely that the string callus is there and can be measured.
The same study had a further question, about sensitivity. A jet of air pressed on the centre of the fingertip with forces of 2 to 7 grams, and the subjects had to say when two pressures were different. The threshold for telling two pressures apart, the smallest difference a person can detect, was higher in the archers, 0.63 against 0.50, and tended to rise where the skin was harder; the authors conclude that it is the callus, rather than a change in the nerves, that takes the fineness away. In fourteen people, though, this is an association, and it cannot separate the skin from the nervous system. There is also a limitation of design: in the controls it was the right hand that was measured, not the bow hand of the archers themselves, so no archer serves as their own comparison.
This is why the registry records as reported the claim that archers tell small differences in pressure on the drawing finger apart less well than non-archers, on the strength of a single study. The finding on skin hardness also feeds a broader entry, the one stating that in the string hand repeated shooting changes the skin and the microcirculation of the fingers, also reported, which holds the skin and the vessels together.
The bow-hand callus
For the bow hand the data are older and come from kyudo, Japanese archery. In 1971 a group of orthopaedic surgeons sent a questionnaire to 122 practitioners aged 18 to 78, then examined and X-rayed the thirty who reported the most marked complaints. In almost all of those thirty the examination found a callus on the left hand, the one that holds the bow, in the area running from the inner side of the joint at the base of the thumb to the web between thumb and index finger, which is where the bow presses in the grip. Other findings in the hand were few: six cases of pain in the long abductor of the thumb, one trigger finger and one stenosing tenosynovitis. In the questionnaire, however, 53 of the 122 had reported complaints in the hand and fingers, without the study saying which.
That "almost all" needs careful reading. It applies to thirty people chosen because they had complaints, not to the 122 who answered the questionnaire, let alone to kyudo practitioners in general; the study gives no percentage and does not say after how many years of practice the callus appears. The claim that in kyudo a callus often forms on the bow hand is therefore reported, on a single descriptive study. The finding does not carry over by itself to the Olympic recurve, where the grip is shaped and the hand pushes with the palm in a different way, and in target archery the bow-hand callus has not been measured.
The small vessels of the fingers
The most delicate part concerns circulation. The clearest data come from a case described in 2020 by a group at the University of L'Aquila: a sixteen-year-old compound archer with five years of practice, shooting three hours a day on three days a week plus one competition, with a 48 lb bow and one to two hundred arrows per session. For about two years she had had pain in her hands, worse over the last year and especially after competitions and long training sessions, and a swollen right hand. Tests for autoimmune and vascular disease were all negative, and MRI of the hands and Doppler ultrasound of the arms showed nothing abnormal.
Capillaroscopy, which uses a microscope to look at the capillaries in the fold at the base of the nail, found something precise instead. In the affected fingers the capillary loops were dilated, with the return limb 35 microns wide against a normal range of 8 to 20, and there were small haemorrhages, granular flow and some oedema. The number of capillaries and their arrangement were normal, so it was the calibre and shape of the vessels that had changed, not their number. Above all, the changes were confined to the index, middle and ring fingers of the string hand, the three fingers that hook the string, while the little finger and every finger examined on the bow hand were normal.
This distribution is the strongest argument for tying the picture to the shot, because a general disease does not pick out three fingers of one hand. It remains a single case, however, and the authors, having ruled out other causes, write that they assume the changes come from the muscular effort and vibration the fingers undergo when shooting. The case does not tell us how often this happens, or whether it happens to archers with a lighter draw weight or fewer arrows.
The other study on the vessels comes from kyudo again, and dates from 2004. Seven university practitioners were compared with other martial arts groups by measuring how the amplitude of the pulse recorded in the finger vessels changes when the arm is raised: in kyudo the response was weaker than in kendo masters, 137% against 233% of the value with the hand at heart level. The difference, however, appeared with both arms, the masters had a mean age of 43.7 against university students, and when the arm was lowered neither the discipline nor the hand made any difference: the study says something about the group and nothing about the string hand in particular. It also adds a detail: while the subjects imagined a tense situation, the finger vessels narrowed without heart rate or breathing changing significantly, in the archers as well.
Taken together, the three studies explain why the claim about the string hand is reported and no more than that: the fingers that hold the string do change, in the skin and in at least one case in the vessels, but the samples are tiny and each study looks at a different piece. How often it happens, and where adaptation ends and damage begins, the studies do not say.
When you get hurt suddenly
The acute side has much larger numbers, and a different story depending on who is counted. In United States emergency departments, from 2013 to 2022, there were about 43,000 archery-related visits on the national estimate, and they tell a story about fingers: in men the finger is the site in 66.2% of cases and the hand in 17.1%, the commonest injury is a laceration, at 58.1%, and nobody was admitted. In women the database records 100% finger lacerations, a figure the authors themselves treat as a limitation rather than a result. That database, however, takes in anyone hurt with a bow and arrows, at home as much as on a farm or at school, without saying whether they were competing, and in men visits peak between the ages of 10 and 19.
Among competitive archers the picture changes. In 62 archers at national and European level, surveyed at the German championship and at a European championship about their whole careers, there are six acute injuries: four bruises to the arm, one cut to the hand from a broken arrow and one to the head, with five cases out of six caused by a bow, arrow or string breaking during the shot, and all of them minor. In 239 archers in Florida, reached at competitions and through clubs, there are seven acute cases, among them bruising, a cut, forearm burns and a broken thumb, and the study does not count them by site.
A 2021 review of Olympic sports took up the study of the 62 competitive archers and stated that in archers 83.3% of acute injuries are fractures. In the original paper that 83.3% is the share caused by equipment breaking, five cases out of six, so the review adds no data and the picture for competitive archers remains one of six cases with the arm at the top.
The studies therefore point in opposite directions, and the claim that acute archery injuries mostly affect the fingers and hand is contested. The difference seems to lie in who is counted rather than in the shot itself: emergency departments see anyone injured with a bow and arrows, in any setting, while the studies of competitive archers see few accidents, nearly all linked to equipment. The fingers also carry little weight among problems that come from repeated load. Among the Florida archers who had been injured, nearly all through overuse, the fingers were involved in 12.9% of cases, and among the 62 competitive archers the finger accounted for 3.9% of overuse injuries, while in both samples the shoulder came first. They are two of the samples behind the claim, reported in the registry, that in archery the shoulder is the most common site of overuse injury. The full picture is in the article on injuries in archery.
On arrows that break there is also a laboratory test, carried out on aluminium kyudo shafts compressed end-on: they buckle, snap exactly in half and leave sharp metal edges. On the basis of that test the registry states that a shaft that buckles on release breaks in the middle and leaves sharp edges, with the status reported; carbon target shafts have not been tested.
Where the studies stop
All of these data are snapshots taken once. Nobody has followed the same archers over the years to see when the string callus forms, whether it grows with the number of arrows or the draw weight, or whether it changes with the type of tab or glove. The capillaroscopy of a single archer does not tell us how many archers have altered capillaries in their fingers, and tingling in the fingers after a long day, as a symptom, has not been counted in the studies of archers. On the acute side, the large numbers come from a database that does not identify competitive archers, while those on competitive archers stop at a handful of cases recalled years later.
What I take from it on the shooting line
The callus on the string fingers is the best documented change, and it is also the one that gives the least cause for concern: harder skin on the fingers that hook the string, with a sensitivity to small differences in pressure that is slightly less fine and, according to the authors of the Japanese study, more stable from one day to the next. Nobody has shown that this changes the release, for better or for worse, so I see it neither as a problem to fix nor as a goal to pursue.
The case of the compound archer shows instead what accompanied, at least in that case, a change that was no longer a simple adaptation: pain in the hands for two years, worse after competitions, a swollen hand and changes concentrated on the three fingers that hook the string. These are not things the studies describe as normal, and that picture was recognised by doctors through a specific examination. So when the string fingers hurt for a long time or swell, the person to see is a doctor, not an article. What the data do allow us to say is that this archer's load was high, and that the changes followed the string grip.
On the acute side, among competitive archers accidents come almost entirely from a piece of equipment breaking. The authors of the German study recommend checking equipment before and after shooting, and for arrows that means looking over the shaft after any impact; nobody has measured how many accidents this prevents, but it is a check that takes a few seconds. The authors of the American study suggest tabs, gloves and arm guards, again without having measured their effect on cuts.