RESUMO
OBJECTIVE: : To assess the validity and reliability of an office-based surrogate measure of lumbar spine-stabilization endurance capability; to establish norms and reliability in an asymptomatic group; and to compare their measures with those from a group of chronic mechanical low-back pain patients. DESIGN: : Eight healthy subjects participated in the tool-validation portion of the study that consisted of surface electromyographic (EMG) measurements of core muscle activation during prone and supine bridging. Subsequently, normative and test-retest reliability measures of prone and supine bridging duration were recorded from 43 subjects without back pain and were compared with those of 32 subjects with chronic mechanical low-back pain. RESULTS: : Surface EMG indicated significantly preferential activation of anterior core muscles during prone bridging and posterior core muscles during supine bridging. Mean bridge durations for subjects without back pain were 72.5 +/- 32.6 (mean +/- SD) secs in prone and 170.4 +/- 42.5 secs in supine. They were significantly less in subjects with back pain: 28.3 +/- 26.8 secs in prone and 76.7 +/- 48.9 secs in supine. Test-retest reliability using Pearson's correlation for prone and supine bridging was 0.78 and 0.84, respectively. CONCLUSIONS: : Bridging maneuvers seem to be practical, reliable, and valid methods of reflecting lumbar spine-stabilization endurance capability. Prone bridging preferentially challenges core flexors, whereas supine bridging recruits primarily the core extensors; both are compromised in patients with low-back pain.
