Muscle activation patterns in shoulder impingement patients

Introduction: Shoulder impingement is one of the most common presentations of shoulder joint problems 1. It appears to be caused by a reduction in the sub-acromial space as the humerus abducts between 60o -120o – the 'painful arc'. Structures between the humeral head and the acromion are thus pinched causing pain and further pathology 2. Shoulder muscle activity can influence this joint space but it is unclear whether this is a cause or effect in impingement patients. This study aimed to observe muscle activation patterns in normal and impingement shoulder patients and determine if there were any significant differences. Method: 19 adult subjects were asked to perform shoulder abduction in their symptomatic arm and non-symptomatic. 10 of these subjects (age 47.9 ± 11.2) were screened for shoulder impingement, and 9 subjects (age 38.9 ± 14.3) had no history of shoulder pathology. Surface EMG was used to collect data for 6 shoulder muscles (Upper, middle and lower trapezius, serratus anterior, infraspinatus, middle deltoids) which was then filtered and fully rectified. Subjects performed 3 smooth unilateral abduction movements at a cadence of 16 beats of a metronome set at 60bpm, and the mean of their results was recorded. T-tests were used to indicate any statistical significance in the data sets. Significance was set at P<0.05. Results: There was a significant difference in muscle activation with serratus anterior in particular showing a very low level of activation throughout the range when compared to normal shoulder activation patterns (<30%). Middle deltoid recruitment was significantly reduced between 60-90o in the impingement group (30:58%).Trends were noted in other muscles with upper trapezius and infraspinatus activating more rapidly and erratically (63:25%; 60:27% respectively), and lower trapezius with less recruitment (13:30%) in the patient group, although these did not quite reach significance. Conclusion: There appears to be some interesting alterations in muscle recruitment patterns in impingement shoulder patients when compared against their own unaffected shoulders and the control group. In particular changes in scapula control (serratus anterior and trapezius) and lateral rotation (infraspinatus), which have direct influence on the sub-acromial space, should be noted. It is still not clear whether these alterations are causative or reactionary, but this finding gives a clear indication to the importance of addressing muscle reeducation as part of a rehabilitation programme in shoulder impingement patients

Nutraceuticals and Human Health

In this Special Issue, we have published papers on the health-promoting effects of nutraceuticals from different sources, and their effects in different pathologies. Extracts from plants have been analyzed, for example, extracts from olive leaves, Mikania micrantha, the devil’s claw, raspberries and others, alongside marine phytoplankton, egg-yolk and marketed dietary supplements. The effects of these extracts and dietary supplements have been studied in diseases associated with obesity, and in diseases where inflammation pathways are involved. The effectiveness of resveratrol and curcumin to support the anticancer activity of cisplatin has also been reported, as well as the ability of devil’s claw root extract to stimulate the CB2 receptors in synoviocytes in osteoarthritis patients. The anti-oxidant effect of marine phytoplankton has been studied on muscle damage, both in humans and in an animal model, and the effects of the metabolite of antocianin were analyzed in a mouse model of amyotrophic lateral sclerosis. Finally, reviews on the use of lactoferrin, ω3 and ω6 and abscisic acid have been reported, in addition to the crosstalk between prostate cancer and microbiota inflammation. Although it is not yet possible to draw definitive conclusions on the use of nutraceuticals, several mechanisms of action for many of them have been further clarified