Energy cost of archery training: Tsuji 1981 study

Six Japanese university archers were measured at rest and while shooting in order to establish how much a normal training session costs in energy. This is the first of two reports, written in 1981 with the declared idea that Japan's Olympic results at the time depended more on physical condition than on technique.

The intensity measured is modest. The total consumption of the sequence, that is, three arrows plus the run out and back over 30 metres to retrieve them, averages 11.07 kcal (from 9.53 to 12.63) in 186 seconds. The relative metabolic rate, which expresses how much is spent above resting metabolism, comes out at 2.2 on average, with a minimum of 1.9 and a maximum of 2.7. In the Japanese classification of the day the authors place that value among “slightly heavy” work, in the same band as a baseball fielder, nine-a-side volleyball, radio calisthenics and walking at four kilometres an hour: the company in that band says more than any label about how much is being spent.

Oxygen consumption while shooting is about twice that at rest (261 ml per minute seated) and touches 2.3 times immediately afterwards; the respiratory quotient rises from 0.77 to 0.84 during the action and to 0.88 afterwards; the pulse goes from 71 to 99 and returns to resting within two minutes. By the third minute of recovery everything is already back.

The correlations, on six people, say three things. The actual draw weight of the bow rises with shoulder and arm strength (r = 0.73 in pushing and 0.50 in pulling). Total consumption rises with body weight (r = 0.73) and with body surface area (r = 0.76). And it falls with years of practice (r = -0.68), which the authors read as a movement that has become more efficient.

In the physical comparison with the Olympic candidates the same authors had measured in 1974, these six stand out in two ways: a smaller chest (85.6 cm in girth) and lower shoulder and arm strength, 42 kg in pulling and 44 in pushing. Height, weight, grip strength, back strength, vital capacity and eyesight do not differ, and in the vertical jump the students are in fact slightly better.

The six were male members of the archery club of a university in Osaka Prefecture, aged twenty and twenty-one, with one to three years of practice (two on average). The entry criterion was the score: at least 320 out of 360 at 30 metres in daily training, that is, 89% of the maximum, which for university students the authors consider a decent level.

The equipment of each archer was measured first. Five used an American Hoyt bow, one a Japanese Y.G. bow, with draw lengths between 27.5 and 29 inches (28.1 on average). The authors distinguish the marked draw weight, which the two manufacturers refer to different points of the bow, from the actual draw weight at the archer's own draw length, measured with a Takei dynamometer and converted into pounds: 36 pounds marked and 36.5 actual on average.

The physical part covers height, weight, chest girth, sitting height, grip strength, back strength, shoulder and arm strength in pushing and pulling, vital capacity, vertical jump and eyesight, with the Takei instruments of the period.

Metabolism was measured by indirect calorimetry with expired air collected in Douglas bags. Basal metabolism early in the morning, fasting; then, thirty minutes before the test, fifteen minutes of rest followed by three five-minute measurements seated for resting metabolism. The test consisted of starting from the shooting stance, loosing three arrows, running the 30 metres to the target at a hundred metres a minute, pulling the arrows and returning to the line at the same pace. One bag collected the whole working period; then, seated, one bag for the first two minutes of recovery, one for the next four and one for the last six. Recovery was taken as complete when the pulse returned to the value measured before the effort.

Total consumption adds the work and the oxygen debt of recovery, calculated by subtracting resting metabolism from the consumption of the first two minutes after the test. The relative metabolic rate was obtained by dividing total consumption by the time of the action and subtracting resting metabolism, following the Japanese method in use at the time.

Six people, all male, all from the same university club, with between one and three years of practice: the correlations reported, from 0.50 to 0.76, rest on six points and are descriptive, nothing more. With a sample like that, a single subject consuming more than the others, as the authors note for one of the six, shifts the picture.

The central measure is not the shooting but the shooting plus the run. The authors say so, and cite an earlier observation that retrieving arrows at a run is the main item of consumption: the run out and back with the arrow pulling took around forty seconds on its own out of a hundred and eighty-six. Their own figure of 2.2 is therefore not the intensity of shooting, and it is higher than the 1.6 or 2.4 another group had found for Japanese archery shot standing still. What the draw alone costs remains to be measured, and the authors list it among the tasks of the next report, together with higher draw weights, up to about fifty pounds.

The poundage here is low, 36.5 actual pounds on average, and the shooting is at 30 metres, the shortest distance in the programme of the day. None of these data describes a modern archer with a competition recurve at 70 metres.

The comparison with the Olympic candidates is the weakest point in terms of soundness: the reference group's data come from a survey by the same authors in 1974, measured seven years earlier on a different group, and appear in the article only as a comparison column. The difference declared significant concerns shoulder and arm strength.

No measure concerns accuracy: the score served to select the participants and is not an outcome. And among the numbers there is a slip: in the Japanese summary the correlation between draw weight and pulling strength appears with a minus sign, while in the results and in the English abstract it is +0.50.

The text is in Japanese, with abstract, tables and figures in English.

This is the work to go back to when discussing how hard archery is in metabolic terms. The answer, on six students with thirty-six pound bows, is: not very. A relative metabolic rate of 2.2 sits in the band of brisk walking, and heart rate returns to resting within two minutes. Anyone looking to archery for cardiovascular training finds here the first figure that cuts the idea down, with the caveat that part of that 2.2 is the run to collect the arrows rather than the shooting.

The second useful finding is the link between draw weight and shoulder and arm strength. The authors look at it the other way round from the usual: they suggest that measuring that strength before choosing a bow might help a beginner pick a suitable poundage. It is a 1981 idea resting on six measurements rather than a tested method, but it remains the first documented attempt to tie a strength measure to the choice of equipment.

The third is the consumption that falls with years of practice. On six people it proves nothing, but it describes what every archer knows: with experience the same movement costs less.

In the registry it counts as a historical reference on the metabolic intensity of shooting and on the physical profile of archers, measured on a tiny sample with the equipment and the distances of the nineteen seventies.