Muscle Activations of the Upper Extremity and Core during Elevation and Rotational Movements in Overhead Throwing Athletes.

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.

Enhanced expectancies benefit performance under distraction, but compromise it under stress: Exploring the OPTIMAL theory.

Motor learning can benefit from practice under enhanced expectancies; that is, the belief one can generate an intended positive outcome. According to the OPTIMAL (Optimizing Performance Through Intrinsic Motivation and Attention for Learning) theory, this benefit manifests from a greater coupling between action and its external consequences, which potentially coincides with a more automatic mode of control. The aim of the study was to examine this possibility, and in so doing, understand more about the psycho-motor processes underpinning the influence of expectancies. On Day 1, novice participants practiced a dart-throwing task under enhanced (EE) (n = 11), reduced (RE) (n = 12) or no (control; CTL) (n = 12) expectancies. Enhanced and reduced expectancies were indirectly manipulated by positively reinforcing shots that landed within the large or small circle on the dartboard, respectively. On Day 2, participants transferred to a dual-task (i.e., tone-counting) or stress (i.e., social-comparative threat, false feedback) setting. While there was no evidence of improvement across practice, RE was significantly worse than CTL for the dual-task, but EE was significantly worse than RE and CTL under stress (ps < 0.05). Therefore, the ability of EE to retain performance within the dual-task, but decline under stress, suggests a more automatic mode of control was adopted. Both theoretical and practical implications are discussed.

Immediate effects of an acute bout of repeated soccer heading on cognitive performance.

Purpose: There isgrowing concern surrounding the harmful effects of soccer heading on cognitive function. The present study aims to examine the immediate effects of heading.Methods: 30 recreational male soccer players were divided into three groups that undertook 20 consecutive headers with a soft (8.8 psi), hard (16.2 psi), or no (control) ball. A battery of neuropsychological tests was completed before and after heading: King-Devick, trail-making (TM) (A, B), digit span (DS) and spatial span (SS) (forward, backward).Results: Significant increase in the time (M = 4.44 s) and errors (M = 1.45) for the King-Devick test within the hard and soft groups, although there was no significant difference for TM-A and TM-B. Significant decline for SS forward within the hard and soft groups (M= -16%), although the declines for SS backward (M = -16%), DS forward (M= -23%) and DS backward (M = -25%) were present only for the hard group (ps <.05).Discussion: While outside of regular match-play, this study showed that heading negatively influenced one indicator of a suspected concussion (King-Devick), as well as working memory (DS, SS) that is essential for daily life. These findings contribute to the growing debate surrounding heading safety.

Effects of exercise and whey protein on muscle mass, fat mass, myoelectrical muscle fatigue and health-related quality of life in older adults: a secondary analysis of the Liverpool Hope University-Sarcopenia Ageing Trial (LHU-SAT).

PURPOSE: To investigate the effects of exercise in combination with, or without, a leucine-enriched whey protein supplement on muscle mass, fat mass, myoelectrical muscle fatigue and health-related quality of life (HR-QOL) in older adults. METHODS: 100 community-dwelling older adults [52% women, age: 69 ± 6 years (mean ± SD)] were randomised to four [Control (C); Exercise (E); Exercise + Protein (EP); Protein (P)] independent groups. E and EP groups completed 16 weeks of exercise [resistance (2 times/week) and functional (1 time/week]. EP and P groups were also administered a leucine-enriched whey protein supplement (3 times/day) based on body weight (1.5 g/kg/day). Muscle and fat mass (bioelectrical impedance analysis), myoelectrical muscle fatigue (surface electromyography) and HR-QOL (WHOQOL-BREF) were measured pre- and post-intervention. RESULTS: At post-intervention, the rectus femoris (E: - 4.8%/min, p = 0.007, ES = 0.86; EP: - 3.3%/min, p = 0.045, ES = 0.58) and bicep femoris (E: - 3.9%/min, p < 0.001, ES = 1.46; EP: - 4.3%/min, p < 0.001, ES = 1.58) muscles became more resistant to fatigue in the E and EP groups, respectively (p < 0.05 versus C). HR-QOL improved in the E group only. Muscle and fat mass did not change (p > 0.05). CONCLUSION: Physical exercise is a potent method to improve myoelectrical muscle fatigue and HR-QOL in older adults. However, leucine-enriched whey protein did not augment this response in those already consuming sufficient quantities of protein at trial enrolment.

The effect of action observation and motor imagery combinations on upper limb kinematics and EMG during dart-throwing.

Recent research has begun to employ interventions that combine action observation and motor imagery (AOMI) with positive results. However, little is known about the underpinning facilitative effect on performance. Participants (n = 50) were randomly allocated to one of five training groups: action observation (AO), motor imagery (MI), simultaneous action observation and motor imagery (S-AOMI), alternate action observation and motor imagery (A-AOMI), and control. The task involved dart-throwing at a concentric circle dartboard at pre- and post-test. Interventions were conducted 3 times per week for 6 weeks. Data were collected from performance outcomes and mean muscle activation of the upper and forearm muscles. Angular velocity and peak angular velocity measurements of the elbow were also collected from the throwing arm. Results showed performance of the A-AOMI group improved to a significantly greater degree than the AO (P = .04), MI (P = .04), and control group (P = .02), and the S-AOMI group improved to a greater degree than the control group (P = .02). Mean muscle activation of the triceps brachii significantly reduced in the S-AOMI and A-AOMI (P < .01) groups, and participants in the AO (P = .04), A-AOMI, and S-AOMI (P < .01) groups significantly reduced activation in the bicep brachii from pre- to post-test. Peak angular velocity significantly decreased from pre- to post-test in both A-AOMI and S-AOMI (P < .01) groups. The results reaffirm the benefits of AOMI for facilitating skill learning and provide an insight how these interventions produce favorable changes in EMG and movement kinematics.

Gaze training supports self-organization of movement coordination in children with developmental coordination disorder.

Children with developmental coordination disorder (DCD) struggle with the acquisition of coordinated motor skills. This paper adopts a dynamical systems perspective to assess how individual coordination solutions might emerge following an intervention that trained accurate gaze control in a throw and catch task. Kinematic data were collected from six upper body sensors from twenty-one children with DCD, using a 3D motion analysis system, before and after a 4-week training intervention. Covariance matrices between kinematic measures were computed and distances between pairs of covariance matrices calculated using Riemannian geometry. Multidimensional scaling was then used to analyse differences between coordination patterns. The gaze trained group revealed significantly higher total coordination (sum of all the pairwise covariances) following training than a technique-trained control group. While the increase in total coordination also significantly predicted improvement in task performance, the distinct post-intervention coordination patterns for the gaze trained group were not consistent. Additionally, the gaze trained group revealed individual coordination patterns for successful catch attempts that were different from all the coordination patterns before training, whereas the control group did not. Taken together, the results of this interdisciplinary study illustrate how gaze training may encourage the emergence of coordination via self-organization in children with DCD.

A randomized controlled trial of a group-based gaze training intervention for children with Developmental Coordination Disorder.

The aim of this study was to integrate a gaze training intervention (i.e., quiet eye training; QET) that has been shown to improve the throwing and catching skill of children with Developmental Coordination Disorder (DCD), within an approach (i.e., group therapy) that might alleviate the negative psychosocial impact of these motor skill deficits. Twenty-one children with DCD were split into either QET (8 male 3 female, mean age of 8.6 years (SD = 1.04) or technical training (TT) groups (7 male 3 female, mean age of 8.6 years (SD = 1.84). The TT group were given movement-related instructions via video, relating to the throw and catch phases, while the QET group were also taught to fixate a target location on the wall prior to the throw (QE1) and to track the ball prior to the catch (QE2). Each group partook in a 4-week, group therapy intervention and measurements of QE duration and catching performance were taken before and after training, and at a 6-week delayed retention test. Parental feedback on psychosocial and motor skill outcomes was provided at delayed retention. Children improved their gaze control and catching coordination following QET, compared to TT. Mediation analysis showed that a longer QE aiming duration (QE1) predicted an earlier onset of tracking the ball prior to catching (QE2) which predicted catching success. Parents reported enhanced perceptions of their child's catching ability and general coordination in the QET group compared to the TT group. All parents reported improvements in their child's confidence, social skills and predilection for physical activity following the trial. The findings offer initial support for an intervention that practitioners could apply to address deficits in the motor and psychosocial skills of children with DCD. TRIAL REGISTRATION: ClinicalTrials.gov NCT02904980.