A task‐relevant experimental pain model to target motor adaptation

Abstract

Motor adaptation is thought to be a strategy to avoid pain. r Current experimental pain models do not allow for consistent modulation of pain perception depending on movement.r We showed that low-frequency sinusoidal stimuli delivered at painful intensity result in minimal habituation of pain perception (over 60 s) and minimal stimulation artefacts on electromyographic signals.r When the amplitude of the low-frequency sinusoidal stimuli was modulated based on the vertical force participants applied to the ground with their right leg while standing upright, we demonstrated a strong association between perceived pain and motor adaptation.r By enabling task-relevant modulation of perceived pain intensity and the recording electromyographic signals during electrical painful stimulation, our novel pain model will permit direct experimental testing of the relationship between pain and motor adaptation.

Gait Adaptation to a Phase-Specific Nociceptive Electrical Stimulation Applied at the Ankle: A Model to Study Musculoskeletal-Like Pain

“…We suggest that this persistent behavior could represent a maladaptive gait modification, according to Hodges and Tucker (2011). Using nociceptive electrical stimulation is therefore a powerful pain model that mimics possible adaptation to modulate pain as shown in Gallina et al (2021) and by our results.…”

“…One main difference, however, is that injections create a tonic continuous pain that rapidly increases and then gradually reduces (Madeleine et al, 1999;Graven-Nielsen et al, 2003). On the contrary, painful electrical stimulation can be triggered at a specific moment of the gait cycle as shown in this study and the pain intensity can be modulated by participants (Gallina et al, 2021). Our model therefore leads to the same effect observed throughout their experiment.…”

“…Even if participants modified their contact duration to modulate pain duration (similar to what has been seen in Gallina et al (2021) with task-relevant modulation of perceived pain intensity), they still maintained their unloading of the painful limb (reduced HC peak pressure) to possibly continue to "protect" the painful limb. We suggest that this persistent behavior could represent a maladaptive gait modification, according to Hodges and Tucker (2011).…”

“…Regarding painful area size and location, the electrical stimulation used in our protocol was localized around the stimulation site (3.3 ± 1.3 cm), similar to the result of Gallina et al (2021). This is a major improvement compared to saline or adenosine injections and ischemic block (Graven- Nielsen et al, 2003), with participants reporting pain in various location below their knee.…”

“…The reduction in single-limb support on the painful limb is similar to what Hodges and Tucker (2011) suggested, however, this protocol cannot control parameters such as pain timing, duration, or intensity. Gallina et al (2021) have recently proposed a pain protocol using low-frequency sinusoidal electrical stimuli and showed that this type of electrical stimulation can induce knee pain of constant intensity for 60 s. However, the stimulation used was continuous. A protocol using nociceptive electrical stimulation that would be phase-specific (i.e., having adjustable pain intensity and present only at an MSK-pain relevant moment of the gait cycle), and being described as an acute MSK-like pain, would be more ecological to study the effects of experimental acute pain on gait motor control.…”