The main objective of this study is:

• To evaluate the immediate hypoalgesic effect of an aerobic exercise session of different intensities in patients with chronic low back pain;

The secondary objective is:

• To explore whether pain intensity, level of physical activity, functionality, catastrophizing, kinesiophobia, anxiety and depression interfere with the immediate hypoalgesic effect of exercise.

There will be 3 groups of participants, an asymptomatic control group that will not perform any exercise and two groups of individuals with low back pain. One group will perform exercise at 90% VO2máx and the other at 60% VO2máx.

All the three groups will be assessed at baseline for pressure pain threshold, pain intensity, pain phenotype, disability, kinesiophobia, catastrophizing, anxiety and depression, physical activity, and aerobic capacity. In addition, pressure pain threshold and pain intensity will also be assessed at post-intervention.

Inclusion Criteria:

• All groups:
• age between 18 and 65 years old
• Participants with low back pain:
• non-specific LBP (defined as pain between the costal margins and the inferior gluteal folds, which is usually accompanied by painful limitation of movement and may be associated with pain referred down to the leg)

Exclusion Criteria:

• All groups:
• presence of pathology of the nervous system, cardiovascular or carcinogenic, rheumatic diseases (for example, rheumatoid arthritis), fibromyalgia, previous history of lumbar surgery, medication that affects or alters heart rate, any contraindication to exercise and pregnancy.