ACUTE EXERCISE-INDUCED HYPOALGESIA AT DIFFERENT EXERCISE INTENSITIES IN PATIENTS WITH CHRONIC LOW BACK PAIN

H. Pinho¹, F. Costa¹, M. Neves¹, A.G. Silva²

¹University of Aveiro, School of Health Sciences, Aveiro, Portugal, ²University of Aveiro, School of Health Sciences and CINTESIS.UA@RISE, Aveiro, Portugal

Background: Low back pain is the leading worldwide cause of disability representing a serious public health problem. Exercise is recommended across most guidelines, but doubts remain regarding the type of exercise to use, its intensity or duration, hindering physiotherapists’ choice of the type and dose of exercise that is likely to be more beneficial for the patient. Recent studies suggest that high-intensity short duration aerobic exercise is effective in producing hypoalgesia. However, the acute effects of an aerobic exercise session remain poorly explored.

Purpose: To compare the acute effect of a 15-minute session of aerobic exercise at high and moderate intensity on pain intensity and pressure pain threshold (PPT) in individuals with chronic non-specific low back pain.

Methods: Participants with chronic nonspecific low back pain were randomly assigned to one of three groups: (I) control group, (II) moderate intensity exercise group, and (III) high intensity exercise group. Participants were assessed at baseline for demographics, pain intensity, pain disability, catastrophizing, and PPT. Pain intensity and PPT were repeated at the end of the exercise session (or an equivalent amount of time in the control group). The submaximal Chester Step Test was used to determine each participant’s aerobic capacity and prescribe the appropriate exercise (moderate or high intensity). Participants in the moderate-intensity group performed 15 minutes of exercise at 30%VO2max, while those in the high-intensity group performed 15 minutes of exercise at 90%VO2max. The control group remained seated for the same amount of time.

Results: A total of 125 participants were screened for inclusion and 83 entered the study (control group: n=26; moderate intensity group: n=27; high intensity group: n=30). No between-group differences were found for baseline data (p>0.05). Mean pain intensity at baseline was 3.7± 0.4 in the control group, 2.9±0.4 in the moderate intensity group, and 2.7±0.4 in the high intensity group. No statistically significant interaction between time and group was found F (2,80) = 1.773, p = 0.176, η2p=0.042), neither there was a significant main effect of time (F (1,80) = 3.505, p = 0.065, η2p = 0.042) for pain intensity. There was a significant main effect of time for the PPT at the low back (F (1,80) = 15.96, p = 0.000, η2p=0.166) suggesting an increase from baseline to post-intervention, but no between-group significant interaction (F (2,80) = 2.82, p ≥ 2.824).

Conclusions: A moderate or high-intensity aerobic exercise session lasting 15 minutes does not impact the intensity of low back pain in individuals with relatively low pain intensities. Also, a moderate and a high-intensity aerobic exercise session lasting 15 minutes and staying seated for an equivalent amount of time are associated with a similar decrease in pain sensitivity. Future work should explore other durations of the exercise sessions and include individuals with higher pain intensity.

Implications: It seems safe to use high-intensity exercise in individuals with low intensity pain and sessions should be longer than 15 minutes to produce hypoalgesia. Also, the Chester Step Test can be easily used in clinical practice as a means to inform exercise intensity.

Funding acknowledgements: This work is financed by national funds through FCT, I.P., within the scope of the project “RISE - LA/P/0053/2020.

Keywords:
Low back pain
Exercise
Exercise-induced hypoalgesia

Topics:
Pain & pain management
Musculoskeletal: spine

Did this work require ethics approval? Yes

Institution: Universidade de Aveiro

Committee: Conselho de Ética e Deontologia

Ethics number: 08-CED/2021