Middle- and long-distance running performance requires a unique blend of physiological characteristics; VO_2max; lactate threshold (LT), anaerobic capacity (sprinting ability) and running economy (RE).  Previous research has demonstrated the importance of VO_2max for distance running performance. However, at higher performance levels (elite or world-class competition), RE has a larger role on performance.  RE is defined as the energy demand for a given velocity of submaximal running, and is typically measured via steady-state oxygen uptake.  Over the last two decades there has been a substantial growth of research demonstrating the beneficial role that strength training (i.e. maximal-strength training, power training and / or plyometrics) has on improving RE in distance runners. Further, there is recent research demonstrating that strength exercises implemented during a warm-up may provide an acute stimulus (i.e. post-activation potentiation [PAP]) to subsequently improve RE during a training session or race. The physiological mechanisms underpinning RE adaptations from strength training is speculated to be due to changes in neuromuscular function (i.e. improved rate of force development [RFD], stretch-shortening cycle [SSC] etc).  However, as the neuromuscular adaptations of sprint training are similar to that of strength training, sprinting may provide a more ‘sport-specific’ stimuli to improve RE in distance runners. Also, distance runners have traditionally utilised ‘strides’ (sub-maximal sprints) in training sessions to improve their sprinting ability.  Nonetheless, there has been a lack of evidence supporting the physiological adaptations of sprinting in distance runners.  Therefore, the aim of this project is to evaluate the effect of sprinting on RE in middle- (i.e. 800m, 1500m) and long-distance runners (i.e. 5000m, 10000m, marathon).  The findings from this innovative project will provide key stakeholders (e.g. Athletics Ireland, Athletics NI, Sport Ireland, Sport NI) with evidence-based research and best practice on utilising sprint training to improve RE within competitive distance running.