(English) episode 270-Your calf muscles are not twins

This perspective article argues that the medial and lateral gastrocnemius muscles should be treated as distinct functional units rather than a single two-headed muscle. The authors present evidence showing that these muscles possess unique anatomical structures, including independent sub-tendons within the Achilles tendon and separate connective tissue envelopes. Furthermore, research indicates they receive different neural inputs, allowing for independent volitional control and specialized activation during varied physical tasks. Biomechanical data reveals significant differences in their force production and torque generation, particularly in the frontal plane of the foot. The text concludes that assuming these muscles behave identically leads to significant errors in musculoskeletal modeling and clinical research. Consequently, the authors urge the scientific community to record and analyze each muscle separately to improve the accuracy of biomechanical studies and wearable technologies.(Aeles J, Hug F. Synergistic yet different: Rethinking the gastrocnemii as two functionally distinct muscles. J Biomech [Internet]. 2026;203(113303):113303. Available from: http://dx.doi.org/10.1016/j.jbiomech.2026.113303)