ABSTRACT
Background: A strong body of literature has been published outlining muscle activity differences during sports performance in groups of overhead athletes. However, there are limited studies that have directly compared the muscle activity in overhead athletes with and without history of shoulder injury during functional everyday tasks. Purpose: This study aimed to identify muscle activities across fourteen upper extremity and core muscles during three functional everyday movements in athletes with and without history of shoulder injury. Study Design: Cross-Sectional Study. Methods: Thirty-two male overhead throwing athletes (fifteen healthy and seventeen injured) were recruited and completed three everyday functional movements of high elevation, low elevation, and rotation, using their dominant arm to move an object between two fixed positions. Electromyography (EMG) was recorded for fourteen muscles including: biceps brachii, deltoids (anterior, medial, and posterior), trapezius (upper and lower), pectoralis major, latissimus dorsi, serratus anterior, infraspinatus, external obliques, and gluteus maximus (all surface electrodes) and supraspinatus (fine wire electrode). Mixed model repeated measures ANOVA and post-hoc analysis assessed mean muscle activity (%MVC) between groups and each movement phase. Results: Upper trapezius elicited higher mean activity in healthy athletes during both phases of the arm rotation task (p \< 0.05). No differences between groups were evident for arm elevation tasks. Qualitative analysis of muscle patterns during functional tasks reflected a temporal shift in muscle activation timings and magnitudes between athlete groups, suggesting potential compensatory mechanisms in injured athletes. Conclusion: Injured overhead athletes appear to utilize other upper limb and shoulder girdle muscles to compensate for lower upper trapezius activity during functional everyday tasks. Level of Evidence: 3.
ABSTRACT
The purpose of this paper was to establish postural cues in kicking that may be of use to goalkeepers. Eight male soccer players (age 20.5 +/- 1.1 yrs; height 1.78 +/- 0.053 m; mass 75.18 +/- 9.66 kg) performed three types of kick: a low side-foot kick to the left hand corner of the goal, a low side-foot kick straight ahead, and a low instep kick straight ahead. Kicks were recorded by an optoelectronic motion analysis system at 240 Hz. At kicking foot take-off (about 200 ms before ball contact) the variables which were significantly different and could act as cues were support foot progression angle, pelvis rotation, and kicking hip and ankle flexion. The support foot progression angle was considered to be the most valuable of these variables as its angle coincided with the direction of ball projection. The other variables were less clear in their interpretation and so less valuable for a goalkeeper to use for decision making. Cues appearing after support foot contact were thought unlikely to be of value to a goalkeeper in their decision making. These include kicking leg knee flexion angle, and support leg shank and thigh angles.
