بررسي ميزان فعاليت عضلات كمر- لگني مؤثر در پايداري core در دوسطح پايدار و ناپايدار در افراد با قوس كمري افزايش يافته

Surface EMG Activity of Core Stabilizer - Lumbopelvic -Muscles On and Off a Swiss Ball With Subjectʹs Hyper lordosis

The purpose of this study was to determine that performing trunk bridging exercises on labile surface influence myoelectric amplitude when compared with a stable surface in both normal lumbar lordosis and hyper lordosis groups. Twenty-five healthy volunteers males were recruited from a convenience sample of collage students and divided to 2 groups (13 subjects in normal lumbar lordosis group: age= 21.00±1.58 years, height= 1.73±0.07 m, mass= 66.69±9.9 Kg, BMI= 22.19±1.68 and 12 subjects in hyper lordosis group: age= 20.42±1.24 years, height= 1.74±0.04 m, mass= 66.76±6.07 Kg, BMI= 22.02±1.48, Lumbo-Sacral Joint Angle = 38.42°±2.99°). Surface electromyography activity were recorded from the selected core muscles -rectus abdominis (RA), external oblique (EO), internal oblique/transvers abdominis (IO/TA) and erector spinae (ES) - while performing bridge exercises on the matt as well as on a swiss ball and normalized to maximum voluntary isometric contraction (MVIC). The results were analyzed by t-test at the 5% level of significance. In both groups during the prone bridge the addition of a swiss ball resulted in increased myoelectric activity in the RA, EO and IO/TA muscles (P<0.05). There were significant increase in the activation of RA, EO and ES muscles during supine bridging on the swiss ball only in hyper lordosis group (P<0.05). No muscles in other exercise conditions showed a change in activation level in both groups. Core muscles activity can be influenced by the addition of surface instability in both groups. Results of the study suggest that prone bridge on a swiss ball is possible to be a useful exercise to restoration of the patterns correct contractions of surface and deep abdominal muscles, particularly in hyper lordosis group. The supine bridge recommend dose not employ in hyper lordosis group through the high level activity of the ES muscles.