Pain intensity and pain sensitivity are not increased by a single session of high-intensity interval aerobic exercise in individuals with chronic low back pain: A randomized and controlled trial

BACKGROUND

Evidence on the acute impact of high-intensity interval aerobic exercise on pain is scarce. This type of exercise might be perceived as increasing pain intensity and pain sensitivity negatively impacting adherence. More evidence on the acute effects of high-intensity interval aerobic exercise in individuals with low back pain (LBP) is needed.

OBJECTIVES

To compare the acute effects of a single session of high-intensity interval aerobic exercise, continuous moderate-intensity aerobic exercise, and no exercise on pain intensity and pain sensitivity in patients with chronic non-specific LBP.

DESIGN

Randomized controlled trial with three arms.

METHOD

Participants were randomly assigned to one of three groups (i) continuous moderate-intensity aerobic exercise, ii) high-intensity interval aerobic exercise, and iii) no intervention. Measures of pain intensity and pressure pain threshold (PPT) at the lower back and at a distant body site (upper limb) were taken before and after 15 min of exercise.

RESULTS

Sixty-nine participants were randomized. A significant main effect of time was found for pain intensity (p = 0.011; η2p = 0.095) and for PPT at the lower back (p < 0.001; η2p = 0.280), but not a time versus group interaction (p > 0.05). For PPT at the upper limb, no main effect of time or interaction was found (p > 0.5).

CONCLUSIONS

Fifteen minutes of high-intensity interval aerobic exercise does not increase pain intensity or pain sensitivity compared to both moderate-intensity continuous aerobic exercise and no exercise, suggesting that high-intensity interval aerobic exercise can be used in clinical practice and patients reassured that it is unlikely to increase pain.

The effects of a 15-week physical exercise intervention on pain modulation in fibromyalgia: Increased pain-related processing within the cortico-striatal- occipital networks, but no improvement of exercise-induced hypoalgesia

Dysfunctional top-down pain modulation is a hallmark of fibromyalgia (FM) and physical exercise is a cornerstone in FM treatment. The aim of this study was to explore the effects of a 15-week intervention of strengthening exercises, twice per week, supervised by a physiotherapist, on exercise-induced hypoalgesia (EIH) and cerebral pain processing in FM patients and healthy controls (HC). FM patients (n = 59) and HC (n = 39) who completed the exercise intervention as part of a multicenter study were examined at baseline and following the intervention. Following the exercise intervention, FM patients reported a reduction of pain intensity, fibromyalgia severity and depression. Reduced EIH was seen in FM patients compared to HC at baseline and no improvement of EIH was seen following the 15-week resistance exercise intervention in either group. Furthermore, a subsample (Stockholm site: FM n = 18; HC n = 19) was also examined with functional magnetic resonance imaging (fMRI) during subjectively calibrated thumbnail pressure pain stimulations at baseline and following intervention. A significant main effect of exercise (post > pre) was observed both in FM patients and HC, in pain-related brain activation within left dorsolateral prefrontal cortex and caudate, as well as increased functional connectivity between caudate and occipital lobe bordering cerebellum (driven by the FM patients). In conclusion, the results indicate that 15-week resistance exercise affect pain-related processing within the cortico-striatal-occipital networks (involved in motor control and cognition), rather than directly influencing top-down descending pain inhibition. In alignment with this, exercise-induced hypoalgesia remained unaltered.

Exercise induced hypoalgesia profile in rats is associated with IL-10 and IL-1 β levels and pain severity following nerve injury

BACKGROUND

Pain may undergo modulation in the central nervous system prior to reaching the primary somatosensory cortex and being perceived as pain. Faulty pain modulation mechanisms have been linked to various chronic pain conditions. Cytokines such as IL-10 and IL-1beta, are known to be involved in initiation and maintenance of neuropathic pain. In this study, we investigated the association between pain modulation profile, pain intensity and cytokines (IL-10 and IL-1beta) levels in a rat model of neuropathic pain.

METHODS

Exercise-Induced Hypoalgesia (EIH) was assessed by evaluating the percentage of responses to a train of 60g mechanical stimuli before and after 180 seconds of exercise on a rotating rod. The differences in the response rates before and after the exercise were used to divide the rats into low and high EIH responders. Rats from low and high EIH groups underwent constriction injury of the left sciatic nerve. Pain behavior (allodynia and hyperalgesia) were assessed by measuring responses to mechanical and thermal stimuli applied to the plantar surface of the foot. Serum, sciatic nerve and the related Dorsal Root Ganglia (DRG) levels of IL-10 and IL-1beta were determined by ELISA. The DRG mRNA levels of IL-10 and IL-1beta measured with PCR. A comparison between the low and high EIH rats of all measured parameters was made.

RESULTS

The low EIH rats developed significantly more severe allodynia and hyperalgesia in the affected paw and allodynia in the contralateral paw compared to the high EIH rats, 7 days following the injury. The low EIH rats had higher IL-1beta protein levels in serum prior to and following injury, higher affected and contralateral sciatic nerve IL-1beta levels following injury and higher IL-1beta levels in the contralateral DRG (protein and mRNA) following injury when compared to high EIH rats. The high EIH rats had higher affected sciatic nerve IL-10 levels following nerve injury and higher IL-10 levels of both protein and mRNA in the affected and contralateral DRG at baseline and following injury.

CONCLUSION

EIH profile was found to be predictive of pain behavior following nerve injury, low EIH rats developed more severe allodynia and hyperalgesia. IL-1beta may be associated with painful neuropathy developed in rats with low EIH while the anti-inflammatory cytokine IL-10 may have a protective role, inhibiting the development of painful.

Pain intensity and pressure pain thresholds after a light dynamic physical load in patients with chronic neck-shoulder pain

Background

To investigate the development of pain intensity and pressure pain thresholds during and 24 h after a light dynamic physical load among patients with chronic neck-shoulder pain.

Methods

Twenty-six patients with chronic neck-shoulder pain and 12 healthy controls were included. The participants arm-cycled on an ergometer. Effort was rated with the Borg Rating of Perceived Exertion scale (RPE), and pain intensity with an numeric rating scale (NRS). Pressure pain thresholds were measured by an algometer. Participants started a pain diary 1 week before the physical exercise and continued until 1 week after. Pain intensity was assessed before, during and the following two evenings after arm-cycling. Pressure pain thresholds were assessed before, 15 min after, 105 min after and 24 h after.

Results

The chronic pain group showed increased pain intensity during, and the following two evenings after the arm cycling, and decreased pain thresholds immediately after the arm cycling involving painful regions. In the patient group there were no impact on pain thresholds in the neck the following day.

Conclusions

Patients with chronic neck-shoulder pain reported increased pain intensity during and in the evenings after a light dynamic load involving painful regions. In addition, they showed decreased pain thresholds close to the exercise, indicating mechanical hyperalgesia.