People with achilles tendinopathy display greater force fluctuations than controls at low force levels
Malliaras P, Tomassoni D, Hasani F, Allan T, Kidgell D
1. Department of Physiotherapy, School of Primary and Allied Health Care, Monash University
2. Department of Physiology, School of Biomedical Sciences, Monash University
Background: People with Achilles tendinopathy (AT) display reduced maximal planterflexor torque , but whether muscle force control tasks are affected is unknown. We aimed to compare planterflexor muscle force control in AT and control groups, and whether torque and muscle force control change following a loading task.
Methods: 11 men with AT and 11 matched controls were recruited. Ankle planterflexor torque during maximal voluntary contraction (MVC) and a 15-second isometric planterflexor force matching task (a measure of muscle force control) at 10% and 50% of MVC (randomised order) were assessed pre-post an isometric task (5 x 45 sec at 70% MVC). Force fluctuations during force matching were quantified using coefficient of variation (CV). MVC torque and force matching were investigated between groups and pre-post the isometric task (ANCOVA with age as the covariate).
Results: The AT group displayed significantly lower MVC torque (F (1) = 6.82, p = 0.017) and greater CV at 10% MVC (F (1) = 7.32, p = 0.014) compared with controls. CV did not change significantly pre-post the isometric task. There was a between group interaction for MVC (F(1,1) = 5.17 p = 0.035), with the AT group displaying a significant increase after the isometric task. Among the AT group, there was a moderate correlation between baseline pain and function and force fluctuations at 10% (r=-0.57, p=0.07).
Conclusion: People with AT display decrement in muscle force control at low force levels that is associated with symptom severity and remained despite increased MVC post a loading task.
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