In previous chapters I have discussed various reasons for including plenty of repetition in training. The benefits of repetition include psychological momentum and the ability to easily track progress. Another potential benefit of repetition in training is reduced injury risk. After all, if injuries tend to follow change, the less your training changes, the more your injury risk falls. Specifically, it is wise to keep your running mileage fairly high year-round, except during breaks between training cycles, and to always include at least a small amount of high-intensity running in your training, as doing so will reduce the incidence of injuries caused by increases in mileage and intensity. In my experience, injuries are much less likely to occur at times when I am running consistently high mileage than at times when I am running less but increasing mileage. It goes without saying that too much repetition in training is as bad as too little, but among competitive runners too little repetition (especially in the form of big swings in weekly mileage and in the amount of high-intensity running) is a far more common error, whose consequences include less consistent fitness development and increased incidence of injury. 5. Impact is everything. The injury rate is much greater in running than it is in swimming and cycling. The difference between running and these other two endurance sports is impact. It is the high-impact nature of running that makes it so injurious. Thus, any reasonable measure you can take to reduce impact forces without compromising the overall quality of your training will enable you to run more with fewer injuries. Eschewing pavement in favor of dirt is perhaps the most proven means of reducing injuries by reducing impact, at least in the real world. As they are in so many ways, East African runners are our role models in this regard. Several years ago I had an interesting conversation about the Africans’ avoidance of pavement with John Connors, a podiatrist with offices in New York City and New Jersey who specializes in the treatment of runners and has developed a cottage industry in treating Kenyan runners in America, including Tegla Loroupe, Catherine Ndereba, and Joyce Chepchumba.