Background:. We have recently shown, using transcranial magnetic stimulation (TMS) to assess voluntary activation (VA), that neural drive to back muscles is reduced in subjects with chronic low back pain. There is also evidence that central nervous system drive to abdominal muscles is altered in these subjects, however VA has not yet been assessed for these muscles in healthy subjects; this is the purpose of the present study. Methods:. Twenty one healthy subjects (10M:11F) participated. Electromyographic activity was recorded from back and abdominal muscles and flexor torque was measured using a dynamometer. Subjects performed a series of isometric voluntary contractions (10%–100% MVC) of rectus abdominis during which TMS was applied to the motor cortex. The resulting superimposed twitches (SIT) were measured and VA was derived. Results:. There was a linear relationship between voluntary torque (50–100% MVC) and SIT amplitude and between voluntary torque (50–100% MVC) and VA. VA at a target torque of 100% MVC was less than maximal (∼86%). Time-to-peak amplitude of SITs displayed a linear relationship with voluntary torque between 10%–100% MVC. Discussion:. This study has shown that it is possible to assess VA of abdominal muscles using TMS. Further, it appears that VA is submaximal during maximum voluntary contractions, similar to that observed in back muscles. This may reflect the function of trunk muscles in general, which are routinely used for maintenance of posture. Whether imbalances of abdominal and back muscle strength observed in low back pain are reflected in imbalances of neural drive to these muscles remains to be investigated

Purpose:. To produce objective evidence that lifting is more comfortable in lumbar flexion than lumbar extension. Traditionally, lifting is taught in lumbar extension (“straight back”) but in our experience is more comfortable and stronger in flexion with backward lumbar tilt. Method and results:. 58 subjects performed maximal comfortable static lifts:. 1. ‘Natural’ lifting position - hip flexion, knee extension, lumbar extension. 2. Traditionally taught position - hip flexion, knee flexion, lumbar extension. 3. Backward pelvic tilt - hip flexion, knee flexion, lumbar flexion. The order of these lifting methods varied to allow for variation due to fatigue/recruitment. All lifts were measured with a computerised dynamometer. The mean force for natural lifting was 13.4 kgs, for traditionally taught lifting 15.1 kgs and for backward pelvic tilt lifting 22.2 kgs. This represented a 13% greater load for traditionally taught lift compared with natural lift, 66% greater for backward pelvic tilt compared with natural lift and 48% greater for backward pelvic tilt compared with traditionally taught lift. Conclusion:. Contrary to accepted teaching and intra-discal pressure studies, this study confirms the observation that lifting strength is greater when the lumbar spine is in flexion. Thus, patients can avoid provoking their back pain when lifting by flexing the lumbar spine. A possible explanation is reduced facet joint compression in lumbar flexion and load sharing with the lumbar fascia and ligaments

Purposes of the study and background. Characteristics of muscle activity, represented by surface electromyography (EMG), have shown differences between patients with low back pain and healthy adults; how they relate to functional/clinical scales remains unclear. The purpose of the current study was to examine the correlation between frequency characteristics of EMG and patients' self-rated score of disability using continuous wavelet transform (CWT) analysis. Methods and Results. Fifteen patients with chronic mechanical low back pain (LBP) and 10 healthy adults were recruited. Patients completed the Roland-Morris Disability Questionnaire (RMDQ) and bilateral EMG activity was obtained from erector spinae at vertebral level L4 and T12. Subjects performed 3 brief maximal voluntary contractions (MVCs) of the back extensors and the torque was measured using a dynamometer. CWT was applied to the EMG signals of each muscle in a 200ms window centred around the peak torque obtained during the MVCs. The ratio (low/high frequencies) of the energy, the peak energy, and the frequency of the peak energy were calculated for each muscle and then averaged and correlated with the individual's RMDQ score. Patients had significantly lower peak power than the controls (p=0.04). Additionally, RMDQ positively correlated to the average ratio of energy (rho=0.71; p=0.01), meaning higher disability corresponded to a dominant distribution of energy in the lower-frequencies; but negatively correlated to the average frequency of peak energy (rho=-0.61; p=0.035), meaning lower frequency of peak energy corresponded to higher levels of disability. Conclusion. The current findings support anatomical evidence of changes in muscle fibre composition of back muscles in subjects with chronic LBP. Conflicts of interest: No conflicts of interest. Sources of funding: No funding obtained

Aims

The purpose of this study was to investigate the prevalence of sarcopenia and to examine its impact on patients with degenerative lumbar spinal stenosis (DLSS).

Objectives

To evaluate the neck strength of school-aged rugby players, and to define the relationship with proxy physical measures with a view to predicting neck strength.