Specific trunk and general exercise elicit similar changes in anticipatory postural adjustments in patients with chronic low back pain : a randomized controlled trial

Study Design. A randomized controlled trial. Objective. To compare changes in self-rated disability, pain, and anticipatory postural adjustments between specific trunk exercise and general exercise in patients with chronic low back pain. Summary of Background Data. Chronic low back pain is associated with altered motor control of the trunk muscles. The best exercise to address altered motor control is unclear. Methods. Sixty-four patients with chronic low back pain were randomly assigned to a specific trunk exercise group (SEG) that included skilled cognitive activation of the trunk muscles in addition to a number of other best practice exercises, whereas the general exercise group performed only seated cycling exercise. The training program lasted for 8 weeks. Self-rated disability and pain scores were collected before and after the training period. Electromyographic activity of various trunk muscles was recorded during performance of a rapid shoulder flexion task before and after training. Muscle onsets were calculated, and the latency time (in ms) between the onset of each trunk muscle and the anterior deltoid formed the basis of the motor control analysis. Results. After training, disability was significantly lower in the SEG (d = 0.62, P = 0.018). Pain was reduced in both groups after training (P < 0.05), but was lower for the SEG (P < 0.05). Despite the general exercise group performing no specific trunk exercise, similar changes in trunk muscle onsets were observed in both groups after training. Conclusion. SEG elicited significant reductions in self-rated disability and pain, whereas similar between-group changes in trunk muscle onsets were observed. The motor control adaptation seems to reflect a strategy of improved coordination between the trunk muscles with the unilateral shoulder movement. Trunk muscle onsets during rapid limb movement do not seem to be a valid mechanism of action for specific trunk exercise rehabilitation programs

Pain reported during prolonged standing is associated with reduced anticipatory postural adjustments of the deep abdominals

Within the context of low back pain, the measurement of deep abdominal anticipatory postural adjustments (APAs) during rapid limb movement has received much interest. There is dispute about the association between APAs and back pain. Moreover, there is limited evidence examining compensatory postural adjustments (CPAs) in back pain. This study examined the relationship between APAs and CPAs with pain reported in the low back during 2 h of prolonged standing. Twenty-six participants with no history of severe back pain performed 2-h prolonged standing. APAs and CPAs of the deep abdominal muscles (transverse abdominis/internal obliques) were measured by surface electromyography during rapid shoulder flexion and extension. APAs and CPAs measured prestanding revealed symmetrical anticipatory activity, but an asymmetry between the different sides of the abdominal wall for CPAs. APAs and CPAs measured pre-standing were not associated with pain reported during standing. For the whole group, APA amplitudes were reduced post-standing during shoulder flexion (p = 0.005). Pain reported during standing was associated with the changes in APA amplitudes post-standing (rs = 0.43, p = 0.002). These findings support previous research using hypertonic saline injections to induce back pain that showed reduced APA amplitudes, and extends findings to suggest pain does not effect compensatory postural adjustments

Relative abdominal adiposity is associated with chronic low back pain : a preliminary explorative study

Background: Although previous research suggests a relationship between chronic low back pain (cLBP) and adiposity, this relationship is poorly understood. No research has explored the relationship between abdominal-specific subcutaneous and visceral adiposity with pain and disability in cLBP individuals. The aim of this study therefore was to examine the relationship of regional and total body adiposity to pain and disability in cLBP individuals. Methods: A preliminary explorative study design of seventy (n = 70) adult men and women with cLBP was employed. Anthropometric and adiposity measures were collected, including body mass index, waist-to-hip ratio, total body adiposity and specific ultrasound-based abdominal adiposity measurements. Self-reported pain and disability were measured using a Visual Analogue Scale (VAS) and the Oswestry Disability Index (ODI) questionnaires respectively. Relationships between anthropometric and adiposity measures with pain and disability were assessed using correlation and regression analyses. Results: Significant correlations between abdominal to lumbar adiposity ratio (A-L) variables and the waist-to-hip ratio with self-reported pain were observed. A-L variables were found to predict pain, with 9.1–30.5 % of the variance in pain across the three analysis models explained by these variables. No relationships between anthropometric or adiposity variables to self-reported disability were identified. Conclusions: The findings of this study indicated that regional distribution of adiposity via the A-L is associated with cLBP, providing a rationale for future research on adiposity and cLBP

Pilates exercise or stationary cycling for chronic nonspecific low back pain : does it matter? : a randomized controlled trial with 6-month follow-up

Study Design.: Randomized controlled trial. Objective.: This is the companion study to a previous publication that presented 8-week pain, disability, and trunk muscle motor control results. The objective of this study was to compare the effect of 8 weeks of specific trunk exercises and stationary cycling on outcomes measures of catastrophizing and fear-avoidance beliefs (FAB) in patients with chronic nonspecific low back pain, and provide 6-month outcome data for all self-report measures. Summary of Background Data.: It is thought that any form of moderate-to-vigorous physical activity is sufficient to address catastrophizing and FAB, and concomitant levels of pain and disability. Methods.: Sixty-four patients with low back pain were randomly assigned to 8 weeks of specific trunk exercise group (SEG), or stationary cycling group (CEG). Self-rated pain, disability, catastrophizing and FAB scores were collected before, immediately after (8 wk), and 6 months after the training program. Clinically meaningful improvements were defined as greater than a 30% reduction from baseline in pain and disability scores. "Intention-to-treat" principles were used for missing data. Per-protocol analysis was performed on participants who attended at least two-thirds of the exercise sessions. Results.: At 8 weeks, disability was significantly lower in the SEG compared with the CEG (d = 0.62, P = 0.018). Pain was reduced from baseline in both the groups after training (P < 0.05), but was lower for the SEG (P < 0.05). FAB scores were reduced in the SEG at 8 weeks, and in the CEG at 6 months. No between-group differences in FAB scores were observed. Similar reductions in catastrophizing in each group were observed at each time point. At 6 months, the overall data pattern suggested no long-term difference between groups. Per-protocol analysis of clinically meaningful improvements suggests no between-group differences for how many patients are likely to report improvement. Conclusion.: Inferential statistics suggest greater improvements at 8 weeks, but not 6 months, for the SEG. Inspection of clinically meaningful changes based on a minimum level of adherence suggests no between-group differences. If a patient with low back pain adheres to either specific trunk exercises or stationary cycling, it is reasonable to think that similar improvements will be achieved

No relationship between body mass index and changes in pain and disability after exercise rehabilitation for patients with mild to moderate chronic low back pain

Study Design. A retrospective multicenter study. Objective. To investigate the relationship between body mass index (BMI) and changes in pain and disability resulting from exercise-based chronic low back pain (cLBP) treatment. Summary of Background Data. Past research has shown evidence of a relationship between BMI, a measurement of obesity, and cLBP. Exercise is a known beneficial treatment for cLBP. However, it is unclear if exercise-induced changes in pain and disability are related to baseline levels of, or changes in, BMI. Methods. One hundred and twenty-eight (n = 128) males and females with cLBP performed 8 weeks of exercise, consisting of 3 to 5 exercise sessions (minimum of 1 supervised session) per week. Outcome measures included BMI and self-reported pain and disability. BMI was calculated as weight divided by height squared (kg/m 2 ). Pain was measured using the visual analogue scale and disability was measured using the Oswestry Disability Index. Correlation, regression, covariance and likelihood ratios analyses were used to examine the relationship between BMI and self reported pain and disability changes. Results. No baseline relationships between BMI and selfreported pain (r = −0.083, P = 0.349) and disability (r = 0.090, P = 0.314) were observed. There was no relationship observed between baseline BMI (P = 0.938, P = 0.873), or changes in BMI (P = 0.402, P = 0.854), with exercise-related changes in pain and disability, respectively. No relationships between baseline BMI or BMI changes with pain and disability at baseline or after exercise were observed on the basis of pain and disability subgroups. BMI was not a predictor of exercise-based pain and disability changes. Conclusion. There was no signifi cant relationship between BMI and self-reported pain and disability in cLBP participants. BMI was not a predictor of exercise-induced changes in pain and disability. The reliance on BMI as a sole measurement of obesity in cLBP research may be unwarranted

The differential effect of metabolic alkalosis on maximum force and rate of force development during repeated, high-intensity cycling

The purpose of this investigation was to assess the influence of sodium bicarbonate supplementation on maximal force production, rate of force development (RFD), and muscle recruitment during repeated bouts of high-intensity cycling. Ten male and female (n = 10) subjects completed two fixed-cadence, high-intensity cycling trials. Each trial consisted of a series of 30-s efforts at 120% peak power output (maximum graded test) that were interspersed with 30-s recovery periods until task failure. Prior to each trial, subjects consumed 0.3 g/kg sodium bicarbonate (ALK) or placebo (PLA). Maximal voluntary contractions were performed immediately after each 30-s effort. Maximal force (Fmax) was calculated as the greatest force recorded over a 25-ms period throughout the entire contraction duration while maximal RFD (RFDmax) was calculated as the greatest 10-ms average slope throughout that same contraction. Fmax declined similarly in both the ALK and PLA conditions, with baseline values (ALK: 1,226 ± 393 N; PLA: 1,222 ± 369 N) declining nearly 295 ± 54 N [95% confidence interval (CI) = 84–508 N; P < 0.006]. RFDmax also declined in both trials; however, a differential effect persisted between the ALK and PLA conditions. A main effect of condition was observed across the performance time period, with RFDmax on average higher during ALK (ALK: 8,729 ± 1,169 N/s; PLA: 7,691 ± 1,526 N/s; mean difference between conditions 1,038 ± 451 N/s, 95% CI = 17–2,059 N/s; P < 0.048). These results demonstrate a differential effect of alkalosis on maximum force vs. maximum rate of force development during a whole body fatiguing task