Effect of Induced Trunk Extensors Fatigue on Balance and Lumbar Position Sense in Adolescent Boys

Background: Fatigue of postural muscles such as lumbar extensor muscles impair postural control and may form the basis for injures, also impair the proprioceptive and kinesthetic properties of load on the vertebral column. Purpose: This study determines the effect of induced fatigue that applied on extensors back muscles immediately and post 30 min on balance and lumber position sense in adolescents. Materials and Methods: Sixty-eight healthy adolescents were chosen, their ages ranged from 16-18 years old, only boys included, they never trained any specific sport before, they have no history of low back pain (intensity1-2 cm) according to 10 cm visual analog scale (green zone), and physical fitness of all participants were (Inactive) according to International Physical Activity Questionnaire- Short Form. Biering-sorenson protocol was applied on all participated adolescents to induce back muscle fatigue, the biodex balance system and digital inclinometer were be used to assess balance (Overall, Ant-Post and Med-Lat stability index) at level 2 stability index and trunk position sense (from 30˚flexion position) respectively, for all participants before application of the fatigue protocol, immediately after and 30 minutes after application. Results: showed a significant increase in the three-stability indices of balance and a significant decrease in lumber position sense immediately after fatigue protocol application compared with pre-induced fatigue, while there was no significant difference in all measured variables between pre-induced fatigue and after 30 min. Conclusion: Induced trunk extensors muscles fatigue has a significant immediate effect on balance and lumbar position sense within 30 min after application of fatigue protocol, these shads the light on preventing musculoskeletal injury and lowering risk in healthy adolescents.