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Updated: Jul 16, 2026
An Instrumented Pull Test to Characterize Postural Responses
Published on: April 6, 2019
Age- and Parkinson-related differences in trunk and lower-limb muscle activation during four balance tasks: A
Jérôme Bouchard-Tremblay1, Michael Théberge2, Tamami Ayoub2
1Programme de Maîtrise en Physiothérapie, Département des Sciences de la Santé l'Université du Québec à Chicoutimi (UQAC), Saguenay, Québec, Canada, G7H 2B1; Centre Intersectoriel en Santé Durable, Laboratoire de Recherche BioNR, Université du Québec à Chicoutimi (UQAC), Saguenay, Québec, Canada, G7H 2B1.
Background:
Poor postural control has been reported in people with Parkinson's disease, which could be explained by the changes in muscular activation patterns related to antigravitational muscles. This study aims to measure the muscle activation of antigravitational muscles during balance tasks in individuals, with and without Parkinson's.
Methods:
Sixteen (16) participants (9 with Parkinson's), aged ≥65 yrs., performed 2 × 30-s trials of 4 balance tasks (bipodal and semi-tandem opened eyes and closed eyes) on a force platform (center of pressure measurement); while surface electromyography measurements were obtained bilaterally on the multifidus at L5, biceps femoris and medialis gastrocnemius. Electromyography amplitude analysis was processed by the Root Mean Square (250 ms window epochs) and normalized by the peak of activation during the balance task, to determine each muscle's activity level.
Findings:
The Parkinson's group reported lower muscle activation than control across tasks (in mean for multifidus = 8%, biceps femoris = 16%, gastrocnemius = 7%), although not statistically significant. Parkinson's reported significantly poorer postural control than control, mainly for the center of pressure sway ellipse area (p = 0.016) from challenge balance tasks such as semi-tandem.
Interpretation:
Poor postural control was confirmed in the Parkinson's group, but not significantly associated by the changes from muscle activation of trunk and lower limbs, during balance performance.
