Pain relief due to physiotherapy doesn't change the motor function of the shoulder.

OBJECTIVE: The purpose of this study is to evaluate the effect of different training methods in physiotherapy on pain relief and change in proprioception and kinesthesia of the shoulder. Further, the connections between pain relief and change in motor function of the shoulder will be investigated. DESIGN: Randomised trial. SETTING: Ambulatory care. PARTICIPANTS: Two groups of unspecific shoulder pain patients (group1 n = 12, group2 n = 10). One group (n = 8) of non-symptomatic subjects. INTERVENTION: The first shoulder-pain group was trained using flexible foil, whilst flexible bands were used to train the patients in the second group. Training period was 12 weeks. MAIN OUTCOME MEASURES: Pain of the shoulder was evaluated through functional pain assessment (Constant-Murley score) before, halfway through and after intervention. Proprioceptive and kinaesthetic ability was measured by an active-active angle-replication test for the shoulder before and after intervention. The data of the shoulder patients was compared to the group of non-symptomatic subjects. RESULTS: Pain was reduced significantly in both groups (p < .05) whereas no changes were measured for the ability to replicate angles of the shoulder. CONCLUSION: This suggests that pain relief in the shoulder is not associated with enhancement of the investigated parameters in motor function.

Activation characteristics of shoulder muscles during maximal and submaximal efforts.

Determination of individual maximum voluntary contraction (MVC) force is used as the gold standard for normalising surface EMG (SEMG) data. Assuming a linear amplitude-force relationship, individual strain levels are defined according to percentage rates of the measured MVC levels. The purpose of the study was to investigate if the assumed force-strain relationship can be applied without qualification. Therefore, healthy volunteers (nine men, ten women) were investigated during isometric exercises of shoulder muscles at MVC and 50% levels. Tasks were performed at four different angular positions in frontal, sagittal and horizontal planes. In each plane, both possible force directions were investigated. SEMG was taken simultaneously from 13 muscles of the shoulder and upper arms from both sides of the body. At a force level of 50% MVC, SEMG amplitude levels were compared to the expected 50% level. Differences in muscular co-ordination patterns were also determined. During retroversion and horizontal flexion, amplitude levels significantly remained at levels below 50%. This was seen for all the muscles investigated, independent of relative contribution to force production. During horizontal extension and abduction, the main force-producing muscles showed amplitude levels that significantly exceeded the expected 50% level. Co-ordination patterns differed significantly between MVC and submaximal conditions for anteversion, retroversion and horizontal extension. Specifically, four shoulder muscles showed higher proportions at the 50% level compared to MVC. Therefore, certain percentage rates of MVC force levels exhibit quite different strain rates, as identified by SEMG. Depending on force direction, differences in co-ordination patterns exist between MVC and submaximal test conditions. Both findings have implications for therapeutic and training applications.

Activation of shoulder muscles in healthy men and women under isometric conditions.

PURPOSE: Due to the low osseous lead of the shoulder joint a large portion of the shoulder muscles, in addition to executing movements, deals with stabilising tasks. This requires a permanent readjustment of the intermuscular co-ordination of all involved muscles. The aim of the study was to verify the existence of gender dependent differences in intramuscular co-ordination patterns of shoulder muscles. METHOD: Fifteen healthy men and nine healthy women, who executed 24 isometric exercises in sagittal, frontal and horizontal planes with a loading of 50% of their individual isometric maximum force, were investigated. In every plane, four angular positions were chosen and both opposite force directions were measured, respectively. SEMG was taken from 13 muscles of the shoulder and the upper arm. Due to inter-individual differences SEMG amplitudes were normalised. RESULTS: Gender specific differences of functional intermuscular co-ordination patterns could be proven systematically. Women showed less activation of muscles acting in the main force direction. In addition, those muscles less necessary for the actual force production were more activated in women than in men. CONCLUSIONS: Functionally comparable shoulder function showed a gender dependency in terms of functional intermuscular co-ordination.