Low back pain is considered one of the great global challenges in public health due to its high prevalence. Exercise have been shown to cause an increase in pain thresholds, through the effect known as exercise-induced hypoalgesia. Little is known about exercise-induced hypoalgesia induced by different modalities of exercise in low back pain, and its possible effects in lumbopelvic biomechanics. The goal of this clinical trial is to compare the effect of exercise-induced hypoalgesia after an isometric, aerobic and a sham/ placebo exercise in non-specific low back pain. The main questions it aims to answer are: * Does an isometric exercise intervention cause exercise-induced hypoalgesia in non-specific low back pain patients? * Is the effect of an isometric exercise intervention comparable to that of aerobic exercise? * Is a placebo/ sham intervention also effective to reduce pain thresholds in these patients? * Do healthy subjects show the same effects in pain thresholds as low back pain patients ? Participants will perform an isometric, aerobic and placebo/ sham exercise intervention in three different recording sessions. Before and after the interventions, pain intensity, pain-pressure thresholds and lumbopelvic biomechanical parameters during trunk flexion-extension will be recorded. Researchers will compare a group of low back pain patients to an age-, gender- and anthropometrics-matched control group of pain-free subjects to see if exercise-induced hypoalgesia is also observed when there is no low back pain diagnosis.
Exercise causes an immediate reduction in pain sensitivity, known as exercise-induced hypoalgesia. This phenomenon is described as the immediate and lasting reduction of pain sensitivity after therapeutic exercise. This effect has been observed after isometric muscle contractions and aerobic exercises in healthy subjects. The hypoalgesic response is often shown as an increase in pain-pressure thresholds in regions close to the most active muscle groups during exercise, and also in regions further away, which probably reflects the activation of systemic endogenous pain inhibitory systems. This effect has also been studied in patients with chronic pain. Although there is previous work that has shown that aerobic exercise and isometric exercise can cause exercise-induced hypoalgesia, there is no evidence on exercise-induced hypoalgesia caused by isometric maneuvers in patients with low back pain. There is also a lack of placebo-controlled studies, or even studies comparing the analgesic effect of isometric and aerobic exercise in this population. Therefore, the aim of this study will be to investigate, in a placebo-controlled intervention, whether various exercise modalities (isometric, aerobic) that involve activation of the lumbopelvic muscles result in local hypoalgesia in the area of the most active muscles, and/or hypoalgesia in more distant areas of the body, in subjects with low back pain and a group of healthy subjects which will serve as a control group.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
SINGLE
Enrollment
76
Biering-Sorensen maneuver.Participants will be in a prone position with the anterosuperior iliac spines on the edge of a stretcher. Their lower body will be strapped by the ankles and hips, with the upper body suspended. Participants will keep their trunk extended and parallel to the ground for 60 seconds.
After adjusting height, pedals and backrest in a cycloergometer, there will be 20 minutes of cycling, of which 5 minutes will be a warm-up at 50-60% of maximum heart rate and 15 minutes at 60-70% of maximum heart rate. There will be a constant monitoring of heart rate and oxygen saturation.
A maneuver equivalent to Biering-Sorensen test, but with upper limb support on a level step and electromyographic monitoring to ensure minimal activation of the erector spinae. It will be explained to the participant that the aim of such an intervention is to cause electromyographic silence of the erector spinae and keep it for 1 minute.
Clinical Anatomy of the Musculoskeletal System Laboratory. Department of Anatomy and Human Embryology, School of Medicine, Universitat de València
Valencia, Valencia, Spain
Pain intensity
Pain intensity will be tested using a visual analogue scale, scored from 0 to 10.
Time frame: Day 1, before, after and 30 minutes past the first intervention. Day 8, before, after and 30 minutes past the second intervention. Day 15, before, after and 30 minutes past the third intervention.
Pain-pressure thresholds
Pain-pressure thresholds will be measured with an algometer on 3 points in a randomized order: 1) thenar eminence; 2) erector spinae (5 cm distal to L3); 3) the center of the long head of biceps femoris. Unit: kg/cm2
Time frame: Day 1, before, after and 30 minutes past the first intervention. Day 8, before, after and 30 minutes past the second intervention. Day 15, before, after and 30 minutes past the third intervention.
Trunk flexion-extension electromyography (EMG)
Average percentages of lumbopelvic muscles activation during flexion, extension, eccentric and concentric contractions and the myoelectrical silence, recorded by an EMG100C Biopac module (Biopac Systems, Inc., Goleta, CA). Unit: percentages of maximum muscle activation
Time frame: Day 1, before, after and 30 minutes past the first intervention. Day 8, before, after and 30 minutes past the second intervention. Day 15, before, after and 30 minutes past the third intervention.
Flexion-extension ratio (EMG)
A ratio between the average lumbopelvic muscles activity at trunk flexion and its average activity at extension, to quantify the relaxation level of the muscle. Unit: dimensionless
Time frame: Day 1, before, after and 30 minutes past the first intervention. Day 8, before, after and 30 minutes past the second intervention. Day 15, before, after and 30 minutes past the third intervention.
Maximum ranges of lumbar and pelvic flexion
Maximum ranges of lumbar and pelvic flexion, in degrees, measured with a Liberty 240/16 electrogoniometer (Polhemus Inc., Colchester, USA). Unit: degrees
Time frame: Day 1, before, after and 30 minutes past the first intervention. Day 8, before, after and 30 minutes past the second intervention. Day 15, before, after and 30 minutes past the third intervention.
Trunk flexion-extension percentages of motion
Average percentages of maximum lumbar and pelvic flexion during flexion and extension, and at the start and end of lumbopelvic muscles relaxation, measured with a Liberty 240/16 electrogoniometer (Polhemus Inc., Colchester, USA) and expressed as a percentage of the maximum range of flexion during each flexion-extension cycle. Unit: percentages of maximum flexion
Time frame: Day 1, before, after and 30 minutes past the first intervention. Day 8, before, after and 30 minutes past the second intervention. Day 15, before, after and 30 minutes past the third intervention.
Time of maximum flexion
Percentage of total flexion-extension time during which the lumbar spine and the pelvis are flexed over 90% of their maximum flexion, measured with a Liberty 240/16 electrogoniometer (Polhemus Inc., Colchester, USA). Unit: percentage of total flexion-extension time
Time frame: Day 1, before, after and 30 minutes past the first intervention. Day 8, before, after and 30 minutes past the second intervention. Day 15, before, after and 30 minutes past the third intervention.
Fear-avoidance beliefs
Fear-avoidance beliefs will be tested using a validated version of the Fear-Avoidance Beliefs Questionnaire (FABQ).
Time frame: Day 1, before, after and 30 minutes past the first intervention. Day 8, before, after and 30 minutes past the second intervention. Day 15, before, after and 30 minutes past the third intervention.
Pain distribution and supra-threshold stimulation
Area of pain irradiation, and area of distribution of pressure-induced referred pain after a supra-threshold stimulation over the infraspinatus muscle. Depicted by the participants on a body chart. Unit: cm2
Time frame: Day 1, before and after the first intervention. Day 8, before and after the second intervention. Day 15, before and after the third intervention.
Anthropometric data: height
Measured with a stadiometer, barefoot. Unit: meters
Time frame: Day 1, before the first intervention. Day 8, before the second intervention. Day 15, before the third intervention.
Anthropometric data: weight
Measured with a calibrated scale with the participant barefoot and wearing light clothes. Unit: kilograms
Time frame: Day 1, before the first intervention. Day 8, before the second intervention. Day 15, before the third intervention.
Date of birth/ age
Self-reported. Unit: years
Time frame: Day 1, before the first intervention.
Sex/ gender
Self-reported
Time frame: Day 1, before the first intervention.
Basic clinical history and occupational data
Self-reported, in an interview. Antecedents of low back pain, occupation
Time frame: Day 1, before the first intervention.
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