Motivation Shoulder impingement (SI) is a common problem for which management approaches lack evidence [1], it is commonly associated with altered motor control of scapulothoracic muscles [2]. This study aimed to elucidate the effects of a motor control (MC) based intervention on pain and muscle function. Method Sixteen SI participants (mean age 24.6 ± 1.6, 11 males) and 16 healthy participants (22 ± 3.1, 11 males) were studied. The Shoulder Pain and Arm Disability Index (SPADI) assessed pain/function. Surface electromyography (EMG) recorded muscle activity of serratus anterior (SA) and three regions of trapezius (upper, middle, and lower (LT)) during arm elevation to 90° and lowering in three planes. Elevation angles were measured by 3-D motion analysis (Vicon, Oxford). Patients were assessed pre and post a 10-week MC intervention, which involved scapular orientation retraining. EMG data were band pass filtered and raw signals were analysed visually for onset and termination of activation, with respect to arm elevation. Analysis between groups was performed by independent and paired t-tests. Results Pre-intervention, patients reported pain and reduced function compared to the healthy participants (pre-intervention 20±9.2; healthy 0±0), these scores improved significantly post-intervention (p<0.001) by a mean of 10 ±4. Pre-intervention, EMG onset was delayed and length of contraction reduced significantly in SA (sagittal and frontal arm elevation) and LT (sagittal and scapular arm elevation) compared to the healthy participants (Table 1). Onset and duration of muscle activity improved significantly post-intervention (p<0.05-0.01) in both SA and LT, reaching similar values to the healthy group (Fig. 1). Conclusions Recovery mechanisms of the clinical effects of the 10 week MC intervention involve improvements in muscle recruitment patterns. It is proposed that MC exercises targeting scapular orientation may be required to improve muscle activation and influence biomechanics, to improve function in SI patients.