Plyometric training (PLYO) improves running economy (RE) and performance in distance races up to 5-km in competitive runners. Core training (CORE) is widely practiced by distance runners, though there is little evidence for its efficacy in improving performance or preventing injury. The purpose of this study was to compare the effects of a weekly PLYO or CORE training program over a 12-week marathon training period on a population of recreational marathon runners. Sprint, jump, and distance running performance, and training variables were assessed. In addition, different approaches to quantifying RE were examined. Competitive (COMP) and recreational (REC) runners were compared, and RE variables were used to model marathon performance. Sprint performance improved with PLYO training. Jump performance was maintained with PLYO training while it decreased in the CORE group. No differences were found in training variables between PLYO, CORE and a no additional training (CON) group, though limited evidence suggests a potential benefit of PLYO training. Other groups increased from baseline (a run-in period of 8 weeks) to the marathon training period in rate of perceived exertion, soreness, and days missed due to injury, while the PLYO group did not experience these negative changes. In addition, pre-marathon creatine kinase (CK) levels were lower in PLYO than CORE runners, and post-marathon CK levels trended toward lower as well. Assessment of RE factors found that correcting 02 utilization for velocity is important in capturing differences between COMP and REC runners, with COMP runners using less O2 per km. This measure was a significant predictor of marathon performance. Within groups, the use of allometric scaling was important in using RE to model marathon performance. Implementation of PLYO training in a population of recreational marathoners can improve sprint and maintain jump performance, but the benefits do not transfer to distance running performance, including RE. Other benefits to health and training variables may be seen, and may be more important to this population. Running economy is an important predictor of marathon performance. Competitive runners are more economical than REC runners, and more economical runners perform better in the marathon, relative to their shorter distance performances.