This study which was conducted by Gabriel Fernandes and supervised by SPRING member Gabriel Trajano investigated how foot positioning during exercise influences muscle activity in runners with Achilles tendinopathy — a common overuse injury that affects the Achilles tendon. The research highlights how pointing the feet inwards (feet-in) during isometric plantarflexion exercises impacts muscle activation patterns in the calf.
The study compared two foot positions — feet-in and feet-neutral — in runners with and without Achilles tendinopathy. Using high-density electromyography, researchers measured muscle activity in the gastrocnemius lateralis (outer calf muscle) and gastrocnemius medialis (inner calf muscle). Results showed that the feet-in position increased activity in the gastrocnemius lateralis in both groups, while reducing activity in the gastrocnemius medialis only in those with Achilles tendinopathy.
Interestingly, while muscle activity increased, motor unit discharge rates — a measure of neural drive to the muscle — decreased in both muscles in runners with Achilles tendinopathy during the feet-in position. This suggests that the higher muscle activation may be due to recruiting more motor units rather than increasing neural drive.
Although the feet-in position appears to shift muscle activity towards the gastrocnemius lateralis, the study notes that further research is needed to determine if this strategy could offer therapeutic benefits for Achilles tendinopathy rehabilitation.
This research provides valuable insights into muscle activation patterns that may help guide more effective rehabilitation programs for injured runners.
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