DELTOID MUSCLE SHEAR MODULUS DURING SUSTAINED SHOULDER ABDUCTION BY ELASTOGRAPHY SUPERSONIC SHEAR WAVE

The muscle elasticity chracterized by shear wave modulus (μ) is a mechanic parameter that is related to tissue stiffnes and is not yet described for deltoid muscle. Few studies describe the variation the μ of a muscle during fatigue. The purpose of this study is: to determine μ of deltoid muscle in the shoulder while performing different positions and to analyse the μ during the isometric fatigue process. Elastographic images were acquired in the medial portion of the deltoid muscle of 18 individuals, in neutral position, with 30 ° of abduction and during shoulder support in 80 ° abduction until the fatigue reported by the individual. Considering the mean μ, there was a significant increase in the neutral position for different joint positions (neutral position μ = 9.04 ± 4.04 kpa, 30 ° abduction μ = 41.04 ± 18.53 kpa, 80 ° abduction μ = 44.63 ± 15.44 kpa). During the shoulder support process, μ variation occurred with significant reduction in 40% of the total time. After suporting process ceased, the fatigue process did not affect stiffness. This study may support future clinical studies or physical conditioning of this musculature.