Protocol for in vivo analysis of muscle function in porcine models for muscular dystrophies

Figures

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  Figure 1. Recommended positioning setup To guarantee accurate biomechanical positioning, the hip (∗), knee (Δ), and hock joints (+) were stabilized at a 90° angle, while the sole was secured to a footplate linked to a highly sensitive torque transducer (#), establishing an ideal physiological setup for generating maximal peak force. Electrodes (Ο) were placed to deliver electrical stimulation to the N. fibularis, with the stimulation current individually fine-tuned to elicit the highest torque response from a single electronic nerve impulse, thereby ensuring targeted activation of the dorsiflexor muscles while preventing engagement of the plantarflexors.

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  Figure 2. Correct electrode placement (A) Schematic overview of the hindlimb muscles: M. tibialis anterior (yellow); M. fibularis tertius (brown); M. fibularis longus (pink); M. fibularis brevis (red); M. flexor digitorum profundus (purple); M. soleus (blue); M. gastrocnemius (green). (B) Picture of a correct electrode positioning.

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  Figure 3. Original slopes (A) Correct trajectories for twitch (left) and tetanus (right). The twitch response shows a single, sharp peak with a steep rise and rapid fall, indicating a properly triggered single muscle contraction. In contrast, the tetanus response displays a clear plateau, reflecting sustained muscle activation. (B) Example of incorrect trajectories, where the characteristic shapes of twitch and tetanus are not clearly distinguishable.