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Activity‐dependent depression of the recurrent discharge of human motoneurones after maximal voluntary contractions

•  During fatiguing contractions, the output of the motoneurone pool decreases despite maximal voluntary drive. The precise mechanism for this reduction is unknown. •  To assess whether changes in the intrinsic behaviour of motoneurones due to their repetitive activity during maximal voluntary contractions are responsible for the reduction of motoneurone output, we measured the recurrent motoneurone discharge produced antidromically by supramaximal stimulation of peripheral nerve. These recurrent responses are known as F‐waves when measured in the EMG. •  Maximal voluntary contractions strongly depressed the probability of occurrence of F‐waves and their area when measured at rest after the contractions. The strength and time course of the depression increased with the duration of the contraction for the abductor digiti minimi muscle. Moreover, the observed depression of F‐waves could not be explained by altered excitability of the peripheral motor axons. •  Hence, we propose that the depression in F‐waves is caused by activity‐dependent changes at the soma or the initial segment and that this may contribute to central fatigue.