(AP) — Groups of hikers and runners who want to do grueling excursions across the Grand Canyon will soon need a permit — a move officials say will cut back on overcrowding, litter and safety issues at the popular tourist attraction in Arizona. The $175 fee will help park officials educate visitors about trail etiquette and free up rangers to respond to life-threatening injuries, Grand Canyon spokeswoman Maureen Oltrogge said. At least one member must be certified in wilderness or emergency medical response and CPR, and there must be general liability insurance. Each participant in her group, which aims to give survivors of medical or traumatic events a life-changing experience, must complete a 16-week training course that includes long hikes at high elevation. Hikers and runners will be advised on yielding to uphill climbers and mules, packing out everything they take in, staying on trails, and not stashing clothing, food and other gear.