Muscle fatigue in the archer: Hamdan 2022 study

A team of engineers at Universiti Malaysia Pahang used electromyography to follow a single recurve archer, a university student with experience of competitions in Malaysia, as he shot 72 arrows at 30 metres outdoors, in two sets of six ends as in a qualification round. The electrodes were on two muscles: the finger extensor in the bow forearm and supraspinatus in the drawing shoulder.

The archer scored 307 in the first set and 318 in the second, with ends between 47 and 57 out of 60; in both sets the lowest scores came in the last three ends. During aiming, the signal amplitude (RMS) was slightly higher in the last end than in the first: from 1.73 to 2.86 for the extensor and from 5.93 to 6.15 for supraspinatus (in units of 10 to the minus 5, with no unit stated), with very large jumps in some of the ends in between. The authors read this as fatigue in both muscles, and point to a fall in supraspinatus median frequency at the fifth end and in the extensor at the eighth as the first signs. An analysis of variance found no link between these measures and the score. The archer said that aiming was the most tiring phase, and towards the end of each set he had to let down and start the shot again several times.

After a warm-up and three sighter ends, the electrodes (an Attys system, linked by Bluetooth to a laptop) were placed on the left forearm and right shoulder of the archer, who was right-handed; six arrows were used to get used to the equipment. There was a break between ends to record the score in an app, and 15 minutes of rest between the two sets. A camera to one side made it possible to match the signal to the drawing, aiming and release phases.

The signal was filtered between 10 and 50 Hz, with a 60 Hz filter against mains interference. For each end, RMS and median frequency during aiming were calculated; the link with score was tested with a two-way analysis of variance for each phase. At the end of the session the archer described how he had felt and what had happened in the weakest ends.

With one archer and one session there is no way to separate fatigue from everything else: wind, light, concentration. The data also do not point the way the authors describe. The extensor's median frequency in the last end is more than ten times that of the first, the opposite of what fatigue should produce, and the values themselves (from 0.03 to 0.9) are not plausible as frequencies in hertz; a filter cutting everything above 50 Hz also removes much of the muscle signal's spectrum, so median frequency says little here. RMS swings far more from one end to the next than it changes between the first and the last, and no statistical test compares those two ends. Finally, the 60 Hz filter does not match the Malaysian mains supply, which runs at 50.

The score went up in the second set, the one where more fatigue would be expected. The authors conclude that the archer handled his fatigue well, but these data give no way of telling whether there was any fatigue to handle.

For archers what remains is a common-sense observation, reported by the archer himself: aiming is the phase that takes the most out of you, and towards the end of a long set you sometimes need to let down and start again. The study says nothing about how many shots it takes before fatigue starts to affect the score, or about which muscles to train. The authors end with advice on training, rest and nutrition that the study did not measure.