EFFECT OF ACUTE EXPERIMENTAL PAIN ON THE Y-BALANCE TEST REACH DISTANCE

M. Bertrand-Charette^1,2, J.-S. Roy^1,2, L. Bouyer^1,2

Background: Following ankle sprains, patients frequently report motor control deficits that are often referred to as instability. This subjective instability can take up to 3 years before it is no longer perceived. The star excursion balance has been described as the most valid and reliable test to assess motor control, while giving insights at proprioceptive capacities after ankle sprains. A short version of this test has been developed showing similar psychometric properties as the original one. However, these tests have mainly studied healthy or chronic participants, and therefore the acute effect of pain on proprioception is still unknown. This acute effect could therefore be of clinical importance for accurate interpretation.

Purpose: The main goal of this project was to assess the effect of acute nociceptive musculoskeletal-like pain at the ankle. Considering that pain may interact with motor control and proprioception, we hypothesized that the painful group would have a decreased reach distance when compared to the other groups.

Methods: 48 healthy participants (24 females, mean age 26.8±3.9) completed twice the Y-balance test separated by a 15-minute break. Following the first assessment, they were randomly assigned to one of three experimental groups: Painless (no stimulation), Painful (nociceptive stimulation; 4/10 on the visual analogue scale) and Control (non-nociceptive stimulation). For these last two groups, two electrodes were placed on the right lateral malleolus to deliver an electrical stimulation during the second test. A mixed model ANOVA was used to compare the reach distance between the two assessments on the raw score and on data normalized to leg length for all groups.

Results: The three groups showed similar characteristics regarding age, height, weight and leg length (P>0.05). The intensity of the electrical stimulation was 9.8±2.4 mA for the Painful group and 2.1±1.1 mA for the Control group. When looking at the mixed model ANOVA, a significant effect of time and an interaction Group*Time was present. Post-hoc tests revealed a significant reach distance decrease for anterior (6.96 cm; p<0.001), posterolateral (6.97 cm; p<0.01) and posteromedial (6.17 cm; p<0.002) directions only for the Painful group when compared to baseline values. Regarding the anterior direction, this decreased range is larger than the minimal detectable change (6.46 cm). No change was observed in the other two groups. When considering normalized data for the Painful group, reach distance decreased of 7.06% (anterior; p<0.001), 7.37% (posterolateral; p<0.01) and 6.53% (posteromedial; p<0.002), and again no changes were present for the other two groups.

Conclusion(s): The presence of acute pain during the execution of the Y-balance test can affect the execution of this test and thus might interfere with the patient’s proprioception. Further studies will include patients with acute painful ankle sprains to validate our MSK-like pain model and to assess the effect of MSK pain on ankle motor control.

Implications: If the presence of pain interferes with ankle proprioception, it could mean that the interpretation of the Y-balance test reach distance should take into account the presence of pain, as it can significantly reduce the participant’s ability to reach further.

Funding, acknowledgements: Fonds de recherche du Québec – Santé (FRQS) and Natural Sciences and Engineering Research Council of Canada (NSERC)

Keywords: Y-balance test, Proprioception, Pain

Topic: Sport & sports injuries

Did this work require ethics approval? Yes

Institution: CIUSSS de la Capitale-Nationale

Committee: Comité d’Éthique de la Recherche Sectoriel en Réadaptation et Intégration Sociale

Ethics number: 2010-212