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Hypoalgesic Effects of Aerobic and Isometric Motor Imagery and Action Observation Exercises on Asymptomatic Participants: A Randomized Controlled Pilot Trial.

OBJECTIVES
The objective was to explore whether action observation (AO) and motor imagery (MI) of aerobic and isometric exercise could induce hypoalgesic responses in asymptomatic individuals compared with placebo observation (PO).


METHODS
A randomized controlled pilot trial was designed. Twenty-four healthy participants (mean age = 21.9 ± 2.1 years) were randomized into three groups: AO+MI (N = 8), AO, (N = 8), and PO (N = 8). All participants performed an actual aerobic running exercise (three series of 90 seconds at 85% of their VO2max and 30 seconds at 65% of their VO2max) and an isometric exercise protocol (isometric squats). A day later, they all performed the mental intervention, observing or imagining exercise execution performed the day before, according to their allocated group. Pressure pain thresholds (PPTs) of the quadriceps and epicondyle regions were assessed at baseline, postintervention, and 15 minutes postintervention.


RESULTS
Analysis of variance revealed statistically significant differences in the group*time interaction for PPT in the quadriceps. The AO group showed a statistically significant increase at postintervention and at 15 minutes postintervention. The AO+MI group obtained a statistically significant increase in the two PPT regions compared with the PO group at Δpre-post. The AO group obtained a greater increase in the PPT in the quadriceps femoris than the PO group at Δpre-post and Δpre-post 15 minutes.


CONCLUSIONS
AO and MI induce hypoalgesic responses compared with PO. AO isolated training showed pain modulation responses in the PPTs of the quadriceps region in young physically active adults. These findings highlight the potential role of brain training in pain management.