Endurance athletes have different needs by sport.
Overall, however there are some common themes across the various sports of running, rowing, swimming, biking, etc. Athletes need to build lean muscle without bulk that will help them be more injury resistant but not slow them down. Building a strong metabolic conditioning base to aid in long races is a key to success. Additionally, at key competitive moments, athletes need to have the power and explosiveness to develop the mental fortitude to dig deep and unleash their anaerobic power, helping them to finish strong, overtake nearby competitors or maintain the lead.