Perceived draw weight in beginners: Eckert 1967

Two researchers at Berkeley set out to see whether beginners can judge how much force feels comfortable at full draw, and whether that judgement is enough to give them the right bow. They tested 49 university students taking an archery course, 28 women and 21 men, at the start of the semester and again after 24 lessons, measuring maximal pull and the pull each one considered comfortable on a modified bow connected to a tensiometer.

Mean maximal pull rose from 40.06 to 45.76 in the women and from 69.46 to 74.59 in the men; comfortable pull rose from 22.64 to 30.57 in the women and from 44.82 to 50.97 in the men, with significant differences in all four cases. The judgement of comfort, however, repeated poorly from one session to the next: the correlation between first and second measurement was 0.421 in the women and 0.337 in the men according to the text (0.377 in the table), against 0.700 and 0.853 for maximal pull.

The link between comfortable pull and the weight of the bows assigned was weak or absent. In the women the only significant correlations concern the first session, 0.455 with the marked draw weight and 0.367 with the measured one; in the men no correlation with the marked draw weight exceeded 0.1. With men and women analysed together the correlations rose (0.618 and 0.535 between comfortable pull and marked draw weight, in the first and second sessions), because the difference in strength between the sexes masked the variation within each group. The authors conclude that the perception of a comfortable pull does not match the force the bow actually requires, and that over a semester it does not adapt to the bow being used.

Pulls were measured at full draw on a bow fitted with a cable, using a cable tensiometer: three consecutive trials for maximal pull and three for comfortable pull, with 30 seconds' rest between them. At the second lesson bows were assigned on the basis of mean comfortable pull, looking only at the marked draw weight and within the range of bows available, since each student's draw length was not yet known: it can only be established once the student has found an anchor point. After four lessons everyone said they were comfortable with the bow they had been given, and they kept it for the rest of the semester.

At the end, besides repeating the tests, the authors measured each student's draw length and the actual weight of the student's bow at that draw length, pulling the string with the cable on a bow clamped to a table; the marked draw weight referred to a 26-inch draw. Reliability of the trials (highest value against the mean of the other two) ranged from 0.907 to 0.978 for maximal pull and from 0.770 to 0.946 for comfortable pull. The analyses are Pearson correlations and t tests, run separately by sex.

Bows had to be chosen from those available, and the authors themselves admit they did not manage to match them to the students' judgement: in the men comfortable pull averaged 44.82, but the bows measured at each student's draw length averaged 30.55, and the marked draw weights varied little (standard deviation 4.74). With bows so far from the judgement and so similar to one another, a low correlation was to be expected whatever the perception. "Comfortable" was not defined, and three trials are too few to identify a comfortable range rather than a single value, as the authors themselves point out.

There is no control group and physical activity outside the course was not recorded, so the gain in strength cannot be put down to the lessons. The sample consists of beginner students in the 1960s, with bows and draw weights far removed from today's, and the paper does not state the unit of the pull measurements, although the values are consistent with pounds. The text and the table disagree at one point (0.337 and 0.377 for the stability of the men's judgement). The study measures neither accuracy nor score, so it does not say whether a "comfortable" bow helps anyone shoot better.

The study addresses a question every instructor knows, choosing a draw weight for beginners, and shows that asking a beginner what weight feels comfortable gives an answer that repeats poorly and has little to do with the bow they will end up using. It also shows that beginners adapt: everyone accepted the bow they were given, even when it did not match their initial judgement.

The most concrete finding concerns the draw weight marked on the bow, which refers to a standard draw length, here 26 inches. For the women in the sample, who evidently had draw lengths shorter than 26 inches (the paper does not report the measurements), the bows measured at their own draw length averaged 21.24 against 26.18 marked, and the two measures were not correlated (0.039); for the men the difference was smaller (30.55 against 33.52) and the correlation high (0.851). For anyone shooting, the weight felt in the hand is the one at their own draw length, which can be several pounds away from the figure printed on the limb.