The purpose of this study was to examine the effects of abdominal hollowing with ultrasound biofeedback on multifidus and transversus abdominis/internal oblique muscle activities during lifting tasks. This study recruited 12 healthy men. All subjects received training on expiration without and with abdominal hollowing with ultrasound biofeedback. After receiving training for each condition, the thickness of transversus abdominis was measured using ultrasound, and then, electromyography activities of transversus abdominis/internal oblique and multifidus during lifting tasks were measured using a surface electromyography system. The differences in thickness of transversus abdominis and electromyography activities of transversus abdominis/ internal oblique and multifidus between the two conditions were analyzed using paired t-test. Thickness of transversus abdominis and transversus abdominis/internal oblique and multifidus activities were significantly increased during expiration with abdominal hollowing with ultrasound biofeedback compared to during expiration without abdominal hollowing (p < 0.05). These findings suggest that abdominal hollowing with ultrasound biofeedback is effective in increasing trunk stabilizer muscle activities during both static and dynamic tasks such as lifting.

INTRODUCTION
 METHODS
  Design
  Subjects
  Ultrasound biofeedback training and measurementof TrA thickness
  EMG signal recording
  Lifting task
  Experimental procedures
  Statistical analysis
 RESULTS
 DISCUSSION
 CONCLUSIONS
 ACKNOWLEDGEMENTS
 REFERENCES

• Min Hyeok Kang Corresponding author