Khassetarash et al. 2021, repeated bouts of downhill running

Study of neuromuscular, biomechanical and energetic adjustments across two downhill running bouts. A first bout caused soreness, force loss and a creatine-kinase rise. On the repeated bout these were markedly attenuated: maximal voluntary contraction fell about 8% versus 17% after the first bout, soreness and CK rises were smaller, and recovery was faster. The repeated-bout protection was attributed mainly to neural adjustments and occurred without a substantial change in the energy cost of running.