A review article published in the Scandinavian Journal of Medicine and Science in Sports provided the most up to date summary on the impact of strength training on endurance running and cycling. This article was a review of the current research, not an individual study. The aim of a review article is to synthesize the published work on a particular topic and to draw conclusions from that body of work.
One of the interesting focuses of the article (although not surprising to us at Discover Strength) was the emphasis on strength training that involves “heavy” weight and a high level of intensity for endurance athletes. This contradicts the long held belief that strength training for distance runners should involve “light” weights for higher numbers of repetitions and the current belief that strength training should be “functional.” The researchers conclude that to improve endurance performance in cycling and running, athletes should train with “heavy” loads and focus on the intent to lift the weight fast at the point of fatigue (for a full description of this concept of “intent,” watch our video from 7 years ago http://www.youtube.com/watch?v=60Tt8U-jp_w). The authors summarize the positive performance effects of “heavy” strength training as improved running/cycling economy, improved anaerobic capacity, improved lactate threshold, improved maximal strength, improved rate of force development, improved maximal speed, improved endurance performance and reduced or delayed fatigue. The researchers also reviewed the evidence for potential negative outcomes of strength training on endurance performance and concluded that there is no research to support any of the hypothesized negative outcomes of strength training for distance runners (for example, the idea that strength training will add muscle and “bulk”).
Take home message: Not only should endurance athletes engage in strength training, but “how” they strength train has important performance related effects.