LOW-BACK LOADS OVER A VARIETY OF ABDOMINAL EXERCISES - SEARCHING FOR THE SAFEST ABDOMINAL CHALLENGE

Abdominal exercises are prescribed for both the prevention and treatme nt of low back injury. However, these exercises sometimes appear to ha ve hazardous effects on the lumbar spine. The purpose of this study wa s to identify quantitatively abdominal exercises that optimize the cha llenge to the abdominal muscles (rectus abdominis, external oblique, i nternal oblique) but impose minimal load penalty to the lumbar spine. Nine volunteers performed 12 different abdominal exercises. For a give n task the maximum abdominal muscle EMG value was divided by the maxim um compression value, resulting in an abdominal challenge versus spina l compression cost index. In general, the partial curl-ups generated t he highest muscle challenge-to-spine cost indices. However, those exer cises that generated the best challenge-to-cost indices did not necess arily record the lowest compression levels along with the highest EMG activations. No single exercise was found that optimally trained all o f the abdominal muscles while al the same time incurring minimal inter vertebral joint loads. It was concluded that a variety of selected abd ominal exercises are required to sufficiently challenge all of the abd ominal muscles and that these exercises will differ to best meet the d ifferent training objectives of individuals.