Longer rest in between intervals will have a greater impact. If they have not conditioned with strength training, the iliotibial band syndrome could be the symptom of tight glutes. The following link will explain this condition in detail and will explain what to do about it:
http://www.spinalhealth.net/inj-itb.html
Shin splints can be resolved with adequate rest, stretching and modifying the exercise routine. Shin splints are small tears in the leg muscles at their point of attachment to the shin, which result from overstressing the lower legs.
Coach Payan
www.coacheseducation.com