Lower trapezius in recurve archers: Liao 2022 study

Fourteen recurve archers from a Taiwanese university team, five men and nine women with a mean age of 19, were followed for twelve weeks: seven added a lower trapezius strengthening programme to their usual training, seven did the usual training only. The split followed the athletes' own preference rather than randomisation.

In the training group the score in a simulated competition, 72 arrows at 70 metres out of a possible 720, rose on average from 628 to 639 (p = 0.045, Cohen's d 0.56). In the control group it fell from 617 to 601, with no statistical difference. The direct comparison between the groups at the final test falls short of the threshold (p = 0.062), but all seven archers in the training group improved while only two of the controls did, and that difference in counts is significant (p = 0.026).

On the muscular side, lower trapezius strength on the bow side went from 8 to 9 kilogram-force and shoulder horizontal abductor strength from 81 to 93% of body weight. At full draw, measured over the second before release, upper trapezius activity fell from 95 to 69% of maximal voluntary contraction on the bow side and from 78 to 44% on the drawing side, while lower trapezius activity held steady: the upper-to-lower trapezius ratio therefore dropped from 2.2 to 1.1 (p = 0.014). Triceps activity also fell (from 26 to 19%) and biceps activity from 42 to 29%. Shoulder angles, both abduction and horizontal extension, did not change in either group.

Recruitment aimed at twenty archers and found fourteen, all using recurve bows and all drawing with the right hand; anyone with previous shoulder surgery, a shoulder muscle disease or subacromial impingement syndrome was excluded.

The simulated competition served as the primary outcome precisely in order to remove the conditions of a real event: 72 arrows at 70 metres, before and after the twelve weeks, on a standard field and in the same weather on both occasions.

The other measures were taken in a laboratory, where each archer shot six arrows at a target 5 metres away, aiming at a one-centimetre mark, with the mean of the six used for analysis. Shoulder angles were captured with an eight-camera system at 100 Hz and skin markers, at the moment the fingers on the string straighten. Surface electromyography, sampled at 1000 Hz, recorded six muscles: upper and lower trapezius on both sides, and on the drawing side the middle deltoid, posterior deltoid, biceps and triceps. Values are expressed as a percentage of each muscle's maximal voluntary contraction, measured against the examiner's resistance in standard positions, and integrated over the second before the arrow leaves. Lower trapezius strength was taken with a hand-held dynamometer in the prone position, and shoulder horizontal abductor and adductor strength with a HUMAC NORM isokinetic dynamometer at 60 degrees per second, normalised to body weight.

The additional programme ran three days a week. For the first four weeks with Thera-Band elastics: reverse fly, straight-arm pull-down, the same in reverse, straight-arm seated row, plus locust and superman on the floor, with 15-second isometric holds, five sets per exercise and 15 seconds between sets. From week five to week twelve the same movements on cable stacks, with a Y-shape lat pull-down added. Ten minutes of warm-up and ten of cool-down, always with at least one trained coach present. The groups were compared with a two-by-two repeated-measures analysis of variance, backed up by effect size, intraclass correlation coefficient and typical error.

Seven archers per group, allocated by their own preference rather than at random: the authors give this as the main limitation, together with the fact that the participants are university athletes rather than elite ones. At these numbers a between-group difference in the final score would have been hard to detect anyway, and it was not detected (p = 0.062); what holds up is the count of how many improved, seven out of seven against two out of seven, which is a coarser measure.

The training group also trained more, because the programme was added rather than substituted: the authors acknowledge that part of the difference may come from the extra time. It is not known whether the assessors knew which group each athlete was in, there is no follow-up, and what the control group did beyond the routine is described only in a supplementary table.

The laboratory measures were not taken under the conditions of the simulated competition: the archers shot at 5 metres at a one-centimetre mark, indoors, wearing markers, and the average comes from six arrows. The upper-to-lower trapezius ratio, which is the most discussed result, has an intraclass correlation coefficient of 0.42 and a coefficient of variation of 60%, making it the least stable of all the measures reported; some electromyography values have coefficients of variation between 33 and 55%.

The authors themselves write that the difference in scores may have many causes and that biomechanics accounts for part of it, listing mental state, the lower limbs and core stability among the others. That a lower upper-to-lower trapezius ratio is an advantage at full draw remains their reading, supported by earlier literature, not something linked here to where the arrows landed. Finally, the journal published a correction to the article on 17 February 2022, registered with its own DOI; the PDF carries the date but does not state what was corrected.

For an archer, the concrete finding is that twelve weeks of work on the scapular stabilisers, three times a week with light loads, went together with a shoulder that shrugged less at full draw: the upper trapezius worked about a third less while the lower trapezius stayed where it was. The score in the simulated competition rose by eleven points out of 720, about 1.5%, in a group starting from 628.

That figure is worth reading for what it is. The direct comparison between the groups at the end does not reach significance, and the firmer result is of a different kind: seven archers out of seven improved their score, against two of seven in the controls. It is a consistent sign, on small numbers.

The study does not show that the exercises change the shot: shoulder angles stayed the same, which the authors put down to the short period. Nor does it show that they prevent anything, since nobody was followed to see whether they got injured. What it shows is that this work, done with elastics and then on cable stacks, shifts the balance of activity between the two parts of the trapezius in a university squad.

One note on context: the participants were university archers scoring around 630 out of 720, which is not international championship level. What would happen higher up, where the margins are tighter, the study does not touch.