The sciatic and radial nerves seem to adapt similarly to different ladder-based resistance training protocols

The present study aimed to compare the morphological response induced by different ladder-based resistance training (LRT) protocols on the peripheral nerve ultrastructure of young adult Wistar rats. Twenty-nine rodents were distributed into groups: control (CON), submaximal (SUBMAX [6 climbs/session, moderate intensity, 3x/week]) and maximum (MAX [> 4 climbs/session, maximum intensity, 3x/week]) LRT. After 8 weeks, the radial and sciatic nerves were removed and prepared for transmission electron microscopy. In the radial nerve, the myelinated fibers and axons, myelin sheath thickness, and unmyelinated axons were statistically greater in the SUBMAX and MAX. The MAX group had greater unmyelinated fibers than SUBMAX. The Schwann cell (SC) nuclei diameter was statistically larger in the SUBMAX than the CON. The number of microtubules and neurofilaments was statistically higher in the SUBMAX and MAX. In the sciatic nerve, the myelinated fibers, myelinated and unmyelinated axons, and myelin sheath thickness were statistically greater in the SUBMAX and MAX. The SUBMAX and MAX had more SC at the nuclei level than CON. The SC nuclei were statistically larger in the SUBMAX and MAX. The number of microtubules and neurofilaments was statistically higher in the SUBMAX and MAX. Total training load and total load per climb were not different between groups. The SUBMAX and MAX statistically increased maximum carried load (ML). In conclusion, the different LRT protocols induced similar morphological responses in radial and sciatic nerves, probably due to load progression and equal total load volume.