Abdominis Activation and Changes in Chronic Low Back Pain
Abdominis Activation and Changes in Chronic Low Back Pain
One hundred and nine patients were included from a previous randomised controlled trial. Activation of the deep abdominal muscles was evaluated before and after an exercise intervention period, and pain was assessed before and 1 year after the intervention. The 87 patients that completed the intervention represent the population in this study (Table 1).
Transversus abdominis lateral slide at baseline was positively, but marginally, related to pain level after 1 year (Table 2, first row) and was also weakly associated with a lower OR for clinically important improvement in pain level at follow-up (Table 3, first row). Delayed or slower first onset of deep abdominal muscles relative to deltoid after the intervention was associated with higher pain at follow-up (Table 2, last row). Contraction thickness ratio in transversus abdominis or obliquus internus was not related to pain at follow-up (Table 2) or odds for improved pain (Table 3).
There was a statistically significant interaction (p=0.04) between baseline and change in transversus abdominis slide in relation to pain, and analysis of the joint effect gave a significantly higher OR for long-term pain improvement (OR 14.7, 95% CI 2.41 to 89.56) for those with low baseline slide and a positive change compared with those with stable or reduced slide after the intervention (Table 4).
In supplementary analyses including three of the muscle activation variables from Table 2 and Table 3 in linear and logistic models, respectively, the sample size was reduced to 46 participants due to missing data. Total R for the linear model with all four variables and the confounding variables was 47% for the change variables and 35% for the baseline variables, with confounders included in both. In the logistic model including all variables, only baseline transversus abdominis slide was associated with the likelihood for an improved pain level (OR 0.75, 95% CI 0.57 to 0.98).
Results
One hundred and nine patients were included from a previous randomised controlled trial. Activation of the deep abdominal muscles was evaluated before and after an exercise intervention period, and pain was assessed before and 1 year after the intervention. The 87 patients that completed the intervention represent the population in this study (Table 1).
Transversus abdominis lateral slide at baseline was positively, but marginally, related to pain level after 1 year (Table 2, first row) and was also weakly associated with a lower OR for clinically important improvement in pain level at follow-up (Table 3, first row). Delayed or slower first onset of deep abdominal muscles relative to deltoid after the intervention was associated with higher pain at follow-up (Table 2, last row). Contraction thickness ratio in transversus abdominis or obliquus internus was not related to pain at follow-up (Table 2) or odds for improved pain (Table 3).
There was a statistically significant interaction (p=0.04) between baseline and change in transversus abdominis slide in relation to pain, and analysis of the joint effect gave a significantly higher OR for long-term pain improvement (OR 14.7, 95% CI 2.41 to 89.56) for those with low baseline slide and a positive change compared with those with stable or reduced slide after the intervention (Table 4).
In supplementary analyses including three of the muscle activation variables from Table 2 and Table 3 in linear and logistic models, respectively, the sample size was reduced to 46 participants due to missing data. Total R for the linear model with all four variables and the confounding variables was 47% for the change variables and 35% for the baseline variables, with confounders included in both. In the logistic model including all variables, only baseline transversus abdominis slide was associated with the likelihood for an improved pain level (OR 0.75, 95% CI 0.57 to 0.98).
