Motor units in the human medial gastrocnemius muscle are not spatially localized or functionally grouped

摘要: Key points Human medial gastrocnemius (MG) motor units (MUs) are thought to occupy small muscle territories or regions, with low-threshold preferentially located distally. We used intramuscular recordings measure the territory of fibres from MG MUs and determine whether these grouped by recruitment threshold joint action (ankle plantar flexion knee flexion). The varied somewhat localized highly distributed, approximately half spanning at least length width muscle. There was also no evidence regional activity based on MU thresholds action. The CNS does not have means selectively activate regions task requirements. Abstract Human territories, distally. In this study, subjects (n = 8) performed ramped sustained isometric contractions flexion; range: ∼1–40% maximal voluntary contraction) we measured size spike-triggered averages fine-wire electrodes inserted along (seven electrodes) across (five Of 69 identified muscle, 32 spanned (≥ 6.9 cm), 11 which all recording sites (13.6–17.9 cm). Distal had smaller pennation angles (P   0.18). in human larger than previously reported action. This indicates that requirements.