If you’re more interested in endurance performance than muscle gains, try adding strength training to your routine. This study showed that adding strength training to a training regimen improved endurance performance more than endurance training alone in experienced athletes.
Source: Aagaard, P., & Andersen, J. L. (2010). Effects of strength training on endurance capacity in top‐level endurance athletes. Scandinavian Journal of Medicine & Science in Sports, 20, 39-47.