The impact of aerobic fitness on functioning in chronic back pain

Paraspinal muscle oxygenation and mechanical efficiency are reduced in individuals with chronic low back pain

This study aimed to compare the systemic and local metabolic responses during a 5-min trunk extension exercise in individuals with chronic low back pain (CLBP) and in healthy individuals. Thirteen active participants with CLBP paired with 13 healthy participants performed a standardised 5-min trunk extension exercise on an isokinetic dynamometer set in continuous passive motion mode. During exercise, we used near-infrared spectroscopy to measure tissue oxygenation (TOI) and total haemoglobin-myoglobin (THb). We used a gas exchange analyser to measure breath-by-breath oxygen consumption (V̇O2) and carbon dioxide produced (V̇CO2). We also calculated mechanical efficiency. We assessed the intensity of low back pain sensation before and after exercise by using a visual analogue scale. In participants with CLBP, low back pain increased following exercise (+ 1.5 units; p < 0.001) and THb decreased during exercise (- 4.0 units; p = 0.043). Paraspinal muscle oxygenation (65.0 and 71.0%, respectively; p = 0.009) and mechanical efficiency (4.7 and 5.3%, respectively; p = 0.034) were both lower in participants with CLBP compared with healthy participants. The increase in pain sensation was related to the decrease in tissue oxygenation (R2 = - 0.420; p = 0.036). Decreases in total haemoglobin-myoglobin and mechanical efficiency could involve fatigability in exercise-soliciting paraspinal muscles and, therefore, exacerbate inabilities in daily life. Given the positive correlation between tissue oxygenation and exercise-induced pain exacerbation, muscle oxygenation may be related to persisting and crippling low back pain.

Are endogenous opioid mechanisms involved in the effects of aerobic exercise training on chronic low back pain? A randomized controlled trial

Aerobic exercise is believed to be an effective chronic low back pain (CLBP) intervention, although its mechanisms remain largely untested. This study evaluated whether endogenous opioid (EO) mechanisms contributed to the analgesic effects of an aerobic exercise intervention for CLBP. Individuals with CLBP were randomized to a 6-week, 18-session aerobic exercise intervention (n = 38) or usual activity control (n = 44). Before and after the intervention, participants underwent separate laboratory sessions to assess responses to evoked heat pain after receiving saline placebo or intravenous naloxone (opioid antagonist) in a double-blinded, crossover fashion. Chronic pain intensity and interference were assessed before and after the intervention. Endogenous opioid analgesia was indexed by naloxone-placebo condition differences in evoked pain responses (blockade effects). Relative to controls, exercise participants reported significantly greater pre-post intervention decreases in chronic pain intensity and interference (Ps < 0.04) and larger reductions in placebo condition evoked pain responsiveness (McGill Pain Questionnaire-Short Form [MPQ]-Total). At the group level, EO analgesia (MPQ-Total blockade effects) increased significantly pre-post intervention only among female exercisers (P = 0.03). Dose-response effects were suggested by a significant positive association in the exercise group between exercise intensity (based on meeting heart rate targets) and EO increases (MPQ-Present Pain Intensity; P = 0.04). Enhanced EO analgesia (MPQ-Total) was associated with a significantly greater improvement in average chronic pain intensity (P = 0.009). Aerobic exercise training in the absence of other interventions appears effective for CLBP management. Aerobic exercise-related enhancements in endogenous pain inhibition, in part EO-related, likely contribute to these benefits.

How effective and efficient are different exercise patterns in reducing back pain?

BACKGROUND

Exercise is considered an effective intervention to relieve chronic back pain. However, it is still unknown whether specific exercise patterns vary in terms of their efficiency and effectiveness.

AIM

To investigate the differential health and economic effects of intensity, specificity and degree of subjective perceived physical exertion across five exercise patterns (endurance, gymnastics, fitness, back gymnastics, multimodal back exercise) in adults with back pain.

DESIGN

Longitudinal observational cohort study over a period of 24 months.

SETTING

Various non-therapeutic exercise facilities (e.g. outdoor, fitness centers, health insurance programs, sports clubs) across one federal state of Germany (Baden-Wuerttemberg).

POPULATION

Adults with back pain (N.=2,542, Mean =46.9 years, 66% females, graded chronic back pain [GCPS] 1=40.5%, GCPS 2=27.3%, GCPS 3=20.7%, GCPS 4=11.5%).

METHODS

Self-reported back pain (functional restrictions and pain = back pain function score, [BPFS]) and characteristics of exercising behavior (frequency, duration, type, physical exertion) were assessed at baseline and at 6, 12, 18 and 24 months. Direct medical costs for back disorders (international classification of diseases, dorsopathies: M40-M54) were compiled from health insurance records.

RESULTS

Moderate- to high-intensity exercise patterns were effective in reducing back pain, particularly at lower levels of subjective perceived physical exertion. At these intensity levels, multimodal back exercise (i.e. exercising the spine-stabilizing muscles specifically, ergonomic training) was 14.5 times more effective than non-back specific fitness exercise in reducing BPFS. The beneficial effects of both exercise types increased with the initial severity of back pain. However, only multimodal back exercise (moderate- to high-intensity/high back specificity) was associated with a significant decrease in direct medical costs for back pain.

CONCLUSIONS

Targeted exercise of the spine-stabilizing musculature at moderate to high intensities without maximum perceived exertion is effective and efficient in reducing back pain.

CLINICAL REHABILITATION IMPACT

The combination of high-intensity and high-specificity exercises yielded a significant reduction in medical costs. However, the intensities in terms of muscular load in endurance training and gymnastics may not be sufficient to reduce back pain effectively.