Archers, fatigue and shoulder therapy: Studnicki 2024

Twenty trained archers from a Polish club shot 100 arrows and then received a session of shoulder manipulation from a physiotherapist, with surface electromyography recorded three times: before the arrows, after the arrows and after the therapy. They were 14 men, averaging 32.1 years, with 5.9 years of practice and about 102 arrows per session, and 6 women, averaging 25.3 years, with 4.5 years of practice and about 132 arrows per session. The muscles measured, on the string arm, were the middle and posterior deltoid, the three parts of the trapezius and the infraspinatus.

After the 100 arrows the only clear change was a rise in the mean amplitude of the middle deltoid, from 196.1 to 248.9 microvolts (p = 0.002). After the therapy the infraspinatus showed higher amplitudes than after the arrows, 169.7 against 109.8 microvolts on average (p = 0.008) and 372.7 against 209.5 at peak (p = 0.010). In the trapezius the peak was lower at baseline than after the arrows (312.6 against 463.9 microvolts, p = 0.014) and than after the therapy (312.6 against 551.2, p = 0.045), and in the middle trapezius it went from 362.8 to 723.4 after the 100 arrows (p = 0.048).

Between men and women there is a single difference in the whole table: the median frequency of the upper trapezius after therapy, higher in the women (83.2 hertz against 71.5; p = 0.037). On everything else the two sexes behave alike. The authors' conclusion is a negative one: shoulder manipulation did not bring the electromyographic parameters altered by the arrows back, and in the case of the infraspinatus it pushed them further out.

The design is experimental but without randomisation and without a control group: a single group, measured three times in the same session. The archers were recruited by convenience, through club announcements and social media; of the 50 considered, 30 were excluded for upper limb injury or because they declined. Inclusion required at least two training sessions a week over the preceding six months, no recent injury or illness and an age of at least 18. Measurements were taken at the training venue between late 2023 and early 2024, in the afternoon, after 48 hours of rest, in a room at 23 °C and 55% humidity.

The first recording was made immediately after the warm-up, which included 10 minutes of dynamic stretching and 5 of isometric exercises for the upper limb; the second five minutes after the hundredth arrow; the third after the manual therapy. Electromyography was recorded on the drawing limb, the right one in 19 of the 20 archers, during the aiming phase, three times per muscle, plus a three-second maximal isometric contraction for each muscle. The device was a TeleMyo DTS with surface electrodes, a gain of 500, a 15 to 500 hertz band-pass filter and sampling at 1,500 hertz; skin preparation and electrode placement followed the SENIAM recommendations. The signal was rectified and smoothed with the root mean square over 300-millisecond windows, yielding mean amplitude, peak amplitude and the median frequency of the power spectrum.

The therapy was a single session, always delivered by the same physiotherapist with 25 years of experience. The archer sat with the limb in internal rotation, extension and adduction, hand and forearm behind the trunk, to put the infraspinatus and the ascending fibres of the trapezius under tension; the therapist took the shoulder capsule from the second to the third grade of tension, held for two seconds and then performed the manipulation in a superior-lateral direction, once per participant. Comparisons were made with a repeated-measures analysis of variance with sex as the between-subject factor, and Bonferroni correction on the follow-up contrasts.

The authors state the central limit themselves: without a control group, what was observed cannot be attributed to the therapy, because between the second and third measurements there is elapsed time, contact with a therapist and waiting. Add to that the sample size, the imbalance between 14 men and 6 women, which makes the comparison between sexes uninformative, and the fact that the sample comes from a single club. The 100 arrows are treated as a fatigue condition, but fatigue was not verified independently: the median frequency of the spectrum, the classic index, moves little and irregularly. Pain, mobility, the archers' own sensations and scores were not measured, so recovery is defined solely as an electromyographic number.

Amplitudes are reported in raw microvolts rather than as a percentage of maximal contraction, which was in fact recorded and appears in a single figure: differences between people therefore depend partly on skin, fat and electrode placement, and the comparison between men and women carries that burden.

There are also internal inconsistencies a careful reader needs to know about. The timings do not match: the description of the setting says the second measurement was taken five minutes after the hundredth arrow, while the paragraph on the therapy says the intervention came after 30 minutes of rest. The results paragraphs for the upper trapezius and the lower trapezius are identical, with the same F values, the same probabilities and the same follow-up contrasts, so one of the two is a copy of the other. The table footnotes refer to a comparison "after 50 shots" that does not exist in this study, because the mid-point measurement belongs to the companion 2026 paper on the same group. Several values quoted in the text, such as the 312.6 and 362.8 microvolts, cannot be derived from the means in the tables. Finally the paper's interpretation is not consistent: the abstract presents the rise in infraspinatus activity after therapy as a sign of efficacy, the discussion as a possible worsening of fatigue, and the conclusion credits the women with an improvement in the middle trapezius that the tables do not show as a difference between sexes.

The most interesting finding for an archer is how little moved. One hundred arrows in a session, which for these archers was their usual volume (102 arrows for the men and 132 for the women on average), clearly changed only one parameter out of eighteen, the amplitude of the middle deltoid. The rest of the shoulder and trapezius muscles, measured during the aiming phase, stayed within normal variation. Anyone who assumes that an ordinary session leaves an electromyographic trace you can read at a glance will not find it here.

On the manual therapy, the reading the paper itself offers is negative, and with this design it is the only prudent one: after the manipulation the parameters did not return to baseline, and in the infraspinatus they went the other way. Whether the manipulation did harm or the muscle was simply behaving that way as time passed, the study cannot tell, because nobody was given rest without therapy. What remains is that nothing an archer actually feels, from pain to stiffness to the quality of the shot, was measured, and that the score never entered the study at all. For a coach the useful message is methodological rather than practical: electromyographic amplitude on its own is a measure of neither fatigue nor recovery.