Elsevier

Human Movement Science

Volume 22, Issue 1, February 2003, Pages 37-45
Human Movement Science

Activation patterns in forearm muscles during archery shooting

https://doi.org/10.1016/S0167-9457(02)00176-8Get rights and content

Abstract

A contraction and relaxation strategy with regard to forearm muscles during the release of the bowstring has often been observed during archery, but has not well been described. The purpose of this study was to analyze this strategy in archers with different levels of expertise; elite, beginner and non-archers. Electromyography (EMG) activity of the M. flexor digitorum superficialis and the M. extensor digitorum were recorded at a sampling frequency of 500 Hz, together with a pulse synchronized with the clicker snap, for twelve shots by each subject. Raw EMG records, 1-s before and after the clicker pulse, were rectified, integrated and normalized. The data was then averaged for successive shots of each subject and later for each group. All subjects including non-archers developed an active contraction of the M. extensor digitorum and a gradual relaxation of the M. flexor digitorum superficialis with the fall of the clicker. In elite archers release started about 100 ms after the fall of the clicker, whereas in beginners and non-archers release started after about 200 and 300 ms, respectively. Non-archers displayed a preparation phase involving extensive extensor activity before the release of the bowstring, which was not observed in elite and beginner archers. In conclusion, archers released the bowstring by active contraction of the forearm extensors, whereas a clear relaxation of the forearm flexors affecting the release movement was not observed.

Introduction

Archery can be described as a comparatively static sport requiring strength and endurance of the upper body, in particular the forearm and shoulder girdle (Mann & Littke, 1989). Skill in archery is defined as the ability to shoot an arrow to a given target in a certain time span with accuracy (Leroyer, Hoecke, & Helal, 1993). The discipline is described as a three-phase (the stance, the drawing and the sighting) movement. Nishizono, Shibayama, Izuta, and Saito (1987) further divided these phases into six: bow hold, drawing, full draw, aiming, release and follow-through. Each of these phases represented a stable sequence of movements and was ideal for studying the motor control and skill acquired during this voluntary kinematic process.

An archer pushes the bow with an extended arm, which is statically held in the direction of the target, while the other arm exerts a dynamic pulling of the bowstring from the beginning of the drawing phase, until the release is dynamically executed (Leroyer et al., 1993). The release phase must be well balanced and highly reproducible to achieve commendable results in a competition (Nishizono et al., 1987).

The bowstring is released when an audible impulse is received from a device called “clicker” that is used as a draw length check (Leroyer et al., 1993). Each arrow can be drawn to an exact distance and a standard release can be obtained using this device (Fig. 1). The clicker is reputed to improve the archer’s score and used by all target archers. The archer should react to the clicker as quickly as possible. In particular, a repeated contraction and relaxation strategy in the forearm and pull finger muscles should be developed for this reason.

The contraction and relaxation strategy in forearm muscle during the release of the bowstring is critical for accurate and reproducible scoring in archery. Two different approaches to this strategy were proposed in previous studies; however, they were not well defined (Clarys et al., 1990; Hennessy & Parker, 1990; Martin, Siler, & Hoffman, 1990; McKinney & McKinney, 1997; Nishizono et al., 1987). The first approach suggested that an archer should release the bowstring through a sudden relaxation of the muscles that maintain the flexed position of the fingers around the bowstring rather than attempting to affect the release moment by willingly extending the fingers through concentric antagonistic muscle action (Martin et al., 1990). In other words, it is suggested that the archer relaxes the flexors, as the force of the string on the fingers is sufficient to produce extension. An active extension of the pull fingers is proposed to produce lateral deflections of the bowstring and to be less consistent with the shot-to-shot performance (McKinney & McKinney, 1997). The second approach suggested the relaxation of the flexors and contraction of the extensors. Muscular coordination between the agonist and antagonist muscles of the forearm is essential in this strategy and requires a relatively long training period (Clarys et al., 1990; Hennessy & Parker, 1990; Nishizono et al., 1987).

Previous studies were not able to clarify the contraction and relaxation strategy of the forearm muscles that was used by archers. All studies were confined to a limited number of elite archers and both strategies were sometimes observed in the same group. Studies did not only involve the forearm muscles that are crucial for accurate and reproducible scoring, but the activity of all upper extremity muscles was measured. Furthermore, the effect of performance level on this strategy was not investigated. It is hypothesized that archers develop a specific forearm and pull finger muscle activation strategy by active contraction of the forearm extensors with the fall of the clicker. Furthermore, the reaction time is expected to be shorter as the level of performance of the archer increases.

Thus, the aims of this study were: (i) to analyze the activation strategy of forearm muscles during archery shooting, and (ii) to investigate the effect of performance on this strategy in elite, beginner and non-archers.

Section snippets

Methods

Three groups, (i) elite (n=10), (ii) beginners (n=10) and (iii) non-archers (n=10), were involved in the study. All groups contained 5 male and 5 female subjects. The first group consisted of national team archers. The second group was formed by beginner archers from the city archery club. The third group included university students with no background knowledge or experience on archery. Information on the participants including the Federation Internationale de Tir à l’Arc (FITA, 1996) scores,

Results

After the fall of the clicker, all archers and non-archers presented an active contraction of the M. extensor digitorum. Elite, beginner and non-archers reached their maximum M. extensor digitorum contraction after about 100, 200 and 300 ms, respectively. The normalized value of the M. extensor digitorum contraction of elite and non-archers was significantly (p=0.010) different at 300 ms after the fall of the clicker.

All archers showed a gradual relaxation of the M. flexor digitorum

Discussion

All archers and non-archers developed an active contraction of the M. extensor digitorum and a gradual relaxation of the M. flexor digitorum superficialis after the fall of the clicker. Active contraction of the M. extensor digitorum can be defined as a forearm and pull finger muscle strategy in archery. Nishizono et al. (1987) considered the M. extensor digitorum as the main muscle engaged in the releasing activity of the bowstring. Active contraction of this muscle was associated with a

Acknowledgements

We acknowledge the contribution of the Middle East Technical University through the Research Fund (Grant no: AFP 2000-050401). We thank to Mr. Gerald Perry, Dipl. Phys. Ed.; Dipl. Physiotherapist, from Doctor and Sport Institute, Universität Landau-Koblenz, Germany for his reviewing and giving feedback about our article.

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