[Isokinetic strength of lumbar muscles in patients with chronic backache]

Deformations of abdominal muscles under experimentally induced low back pain

PURPOSE

Low back pain (LBP) is associated with altered motor control and muscle activity; however, it remains unknown whether these changes predispose humans to injury and pain or are the consequence of ongoing nociceptive processes. In this experimental study, we aimed to use a novel ultrasound imaging technique for the measurement of lateral abdominal wall muscle activity: the tissue deformation index (TDI).

METHODS

Forty-two healthy subjects (22.30 ± 1.49 years of age) were exposed to postural perturbation induced by rapid arm movement. Activity of three muscles, the transversus abdominis (TrA) and the internal and external oblique (EO), was recorded by ultrasound imaging (M-mode) with and without induction of LBP. Pain was induced by electrical stimulation applied bilaterally to the lumbar spine.

RESULTS

No significant differences in the TDI between right and left sides of the body (p > 0.05) were found. Generally, muscles deformed slower with pain compared to non-painful conditions; however, only EO muscle displayed a statistically significant reduction in deformation velocity (p ≤ 0.00001). TDI for EO decreased from 0.065% per ms ( ± 0.038, 95% CI 0.057-0.074) to 0.053% per ms ( ± 0.035, 95% CI 0.046-0.061). Furthermore, characteristic inter-muscular TDI gradients were observed, directed from inner towards outer muscular layers, with TrA showing the lowest TDI and EO the highest.

CONCLUSION

Experimentally induced LBP suppresses deformation of the superficial abdominal muscles and increases the variability of local/deep muscles. Further research is required to confirm these observations. These slides can be retrieved under Electronic Supplementary Material.

[Evaluation of the German new back school: muscular physiological characteristics]

BACKGROUND

According to the biopsychosocial approach of the German new back school the core objectives are sustainable improvement of physical and psychosocial health resources. Subjects with non-specific low back pain were investigated to evaluate the desired physical effects.

METHODS

Coordinative and postural motor exercises were evaluated by means of surface electromyography (EMG). Applying a modified waiting group design 56 participants were examined 3 months before the start, at the beginning and at the end of the new back school program as well as 3 and 12 months after completion and the results were compared to a healthy control group (n=56) matched for age and body mass index (BMI).

RESULTS

Initially significant group differences were found in 18 % of all statistical calculations of the static and 6 % of the dynamic test situations. Considering the trunk muscles the most frequent significant alterations from normative data were found in the lumbar multifidus muscle (static tests 29 % and dynamic tests 7 %). No relevant changes in the number of statistical results could be detected directly after completion of the new back school program. Nevertheless, at 12 months follow-up the number of significant differences to the normative data of the control group dropped by one third to 12 % of all calculations with static loads.

CONCLUSION

The adjustment effects at 12 months follow-up indicate a delayed positive influence of the new back school program on muscular physiological parameters. Individuals with chronic non-specific back pain showed a long-term profit from participation in the new back school program due to the initiated orientation to a modified more active lifestyle.

Trunk muscular strength in pre-pubertal children with and without back pain

OBJECTIVE

While in adulthood there is no proven relationship between back pain and trunk muscle strength, in pre-pubertal subjects this topic has been poorly studied. The aim of the study was to evaluate isometric and isokinetic trunk muscle strength in children with or without previous back pain.

METHODS

The recent occurrence of back pain (last 6 months) among 144 children (77 males, 67 females, age 11.9 +/- 0.3 years) was assessed using a questionnaire. Extensor and flexor trunk muscle strength was measured through isometric and isokinetic (60, 90, 120 degrees/s) tests. Peak torque (PT), PT angle, PT flexor/PT extensor ratio and intra-session coefficient of variation (COV) were determined.

RESULTS

Flexor and extensor muscle PT, but not PT angle, were significantly higher in males than in females, irrespective of back pain occurrence. PT flexor/PT extensor ratio at 90 degrees angular velocities increased significantly only in males with back pain, compared with males without back pain. The COV trend was similar for flexor and extensor muscles.

CONCLUSIONS

Isometric and isokinetic trunk muscle strength probably play a minor role in back pain occurrence in children. The isokinetic testing velocity may be important in determining trunk strength differences between children with and without back pain.