Fig. 1

The experimental method

(a). Research group. (Con: control group, TS: Tail suspension group, Pre-H: HFES before TS intervention, Dur-H: HFES during TS, H-H: HFES before and during TS, H-L: HFES before TS plus LFES during TS, L-H: LFES before TS plus HFES during TS, L-L: LFES before and during TS). (b). Skeletal muscle atrophy model: rat tail suspension. (c). Illustration of Electrical stimulation on muscle. In the electrical stimulation procedure, two steel needles were used as electrodes and connected to the stimulator. The positive electrode was positioned behind the junction of the two gastrocnemius muscle bundles, near the peroneal nerve, while the negative electrode was placed at the lower end of the ventral part of the gastrocnemius muscle and close to the Achilles tendon. (d). To test the mechanical properties of the gastrocnemius muscle, a wire was attached to the distal end of the gastrocnemius tendon. External electrical stimulation was applied, causing the gastrocnemius muscle to contract, and allowing the measurement of the mechanical changes resulting from different electrical stimulation signals