What specific strength training exercises can be implemented to significantly boost a cyclists speed and power output, particularly in sprints and hill climbs, while also considering the importance of injury prevention and optimal recovery time? Are there any exercises that target multiple muscle groups simultaneously, allowing for a more efficient use of training time, and if so, how can they be effectively incorporated into a periodized training program? How do the benefits of strength training, such as increased muscle efficiency and neuromuscular coordination, translate to improved cycling performance, and what are some key indicators of progress and success in a strength training program for cyclists?