This is the 'working' part of the Sportsmedicine article that Mike T brought to our attention; it's the neuromuscular function that's important. At least that's my take on it, so if anyone knows any better ...
Heavy resistance and plyometric training, which are effective to enhance neuromuscular function, have recently drawn researchers’ attention as a potential training modality that improves running economy and running time trial performance [7, 8]. The reason behind this interest is that the energy cost of skeletal muscle represents majority of the total energy cost of running [9, 10]. Heavy resistance training can increase muscular strength and/or power by changing motor unit recruitment patterns and firing frequency during voluntary muscle contractions [11, 12]. An increase in muscle strength could lower the relative intensity of the load for exercising muscles during running [9]. Consequently, it may contribute to improvements in running economy and running time trial performance [9, 13].