In this study, we contend the firing properties of motor units change due to nonphysiological sources. We specifically ask whether changes in the fibular nerve length, without a concurrent change in tibialis anterior architecture, affect motor unit firing and recruitment strategies. We tested this hypothesis based on high-density surface electromyograms (EMGs) collected from the tibialis anterior of 18 healthy young adults for two hip postures, flexed and extended. To control for changes in peripheral nerve length, conduction time between electrical stimulation and generation of compound action potentials in extensor digitorum brevis was measured for the two hip postures during rest. Motor units were decomposed from EMGs obtained during sustained isometric dorsiflexion at 10% of the maximal voluntary contraction (MVC), and during ramp isometric contractions up to 20% MVC. Individual motor unit firings were identified and tracked between the two postures. Nerve conduction time was significantly shorter in hip flexed than in hip extended posture (