The aim of this study was to investigate the contributions to stick motion in the field hockey hit by monitoring muscle activity in the arms and trunk and synchronising these with arm and stick kinematics. The hits of ten male, university-level field hockey players were analysed. Whilst their interpretation is complicated by the closed kinetic loop formed by the arms and stick, the data collected here represent a step forward in establishing the contributions from muscular activity

and segmental interactions to the field hockey hit. This study has shown that EMG analysis alone is not sufficient to explain the nature of muscular activity patterns and that the temporal aspects of EMG need to be examined in combination with kinematic data to ascertain the role of muscular activity during movement

Gorman, Anthony J.

Willmott, Alexander P.

English

University of Lincoln Institutional Repository

The Timing and Magnitude of Upper Body Muscular Activity During a Field Hockey Hit A.  J. Gorman and A. P. Willmott School of Sport and Exercise Science, University of Lincoln, UK Methods The hits of ten male, university-level field hockey players were analysed using surface EMG (Myomonitor IV, Delsys). Bilaterally, activity was recorded at 2000Hz from the biceps brachii, triceps brachii, anterior and posterior deltoids, upper trapezius, latissimus dorsi and sternal and clavicular pectoralis major muscles. Stick, elbow and wrist kinematics were tracked at 240Hz using eight Qualisys ProReflex 500 cameras, and each hit was broken down into four phases: the backswing (BSw), early forward swing (EFSw), acceleration (Acc) and early follow-through (EFTh). Kinematic and EMG data were then synchronised and temporally normalised to % of each phase. EMG amplitudes were normalised to maximal voluntary contractions.  Results The elbow and wrist motions (Figure 2) confirmed Chivers and Elliott’s (1987) suggestion that the left arm and stick act as a double pendulum, but the right arm and stick act as a triple pendulum. Table 1 shows the peak EMG amplitude in each phase for selected muscles, but detailed activity patterns were also established relative to the kinematic data.  Discussion  Right anterior deltoid, right pectoralis major and bilateral latissimus dorsi activity initiates the EFSw, causing the early acceleration of the arms. Segmental interactions, arising from these accelerations, cause the wrists to ‘cock’. A combination of left anterior deltoid, left latissimus dorsi and bilateral pectoralis major activity accelerates the arms during the downswing whilst elbow musculature appears to control the elbow flexion tendency arising from segmental interactions. These interactions then become involved in wrist ‘uncocking’ as the stick accelerates towards impact with the ball. These combined effects cause the right elbow to flex then extend, whereas the left elbow maintains a more constant degree of extension throughout the hit.  References Chivers, L. and Elliott, B.C. (1987) The penalty corner in field hockey. Excel. 4: 5-8. Table 1. Peak amplitude (%MVC) of muscle activity by swing phase during the field hockey hit (mean ± SD, across all participants) Figure 2. Elbow and wrist angles during the field hockey hit. Values shown are the mean angles ± SD across all participants for each normalised percentage of each swing phase, where 180 degrees is full extension. Introduction The field hockey hit is one of the most important skills used in the game, but surprisingly little is known about its underlying kinetics. The aim of this study was to investigate the contributions to stick motion by monitoring muscle activity in the arms and trunk and synchronising these with arm and stick kinematics. Figure 1. The field hockey hit: a) initiation of the hit and start of the backswing; b) top of the hit, the end of the backswing and the start of the early forward swing; c) stick horizontal in the downswing, the end of the early forward swing and the start of the acceleration phase; d) ball impact, the end of the acceleration phase and the start of the early follow-through; e) stick horizontal, the end of the early follow-through and the start of the late follow through; f) end of the hit. Discussion Activity of the right anterior deltoid, right pectoralis major and both latissimus dorsi initiates the EFSw, accelerating the arms. Segmental interactions, arising from these accelerations, cause the wrists to ‘cock’. A combination of left anterior deltoid, left latissimus dorsi and bilateral pectoralis major activity continue to accelerate the arms during the early downswing whilst elbow musculature appears to control the elbow flexion tendency of both arms arising from segmental interactions. The ‘locking’ of the elbows means the effect of segmental interactions are seen at the wrists, which become involved in wrist ‘uncocking’ as the stick accelerates towards impact with the ball. With relation to the whole motion, the elbows differ as the combined effects of muscular activity and segmental interactions cause the right elbow to flex then extend, whereas the left elbow maintains a more constant degree of extension throughout the hit. Conclusions Whilst their interpretation is complicated by the closed kinetic loop formed by the arms and stick, the data collected here represent a step forward in establishing the contributions from muscular activity and segmental interactions to the field hockey hit. This study has shown that EMG analysis alone is not sufficient to explain the nature of muscular activity patterns and that the temporal aspects of EMG need to be examined in combination with kinematic data to ascertain the role of muscular activity during movement.   Elbow	  Angle	  (°)	  Wrist	  Angle	  (°)	  

The timing and magnitude of upper body muscular activity during a field hockey hit

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