问题：
.ReadingComprehension（2.0分）
答案：
ere are fewer predefined movements in parkour than gymnastics, as it does not have a list of appropriate "moves." Each obstacle a tracer faces presents a unique challenge on how they can overcome it effectively, which depends on their body type, speed and angle of approach, the physical make-up of the obstacle, etc. Parkour is about training the body mind to react to those obstacles appropriately with a technique that works. Often that technique cannot and need not be classified and given a name. In many cases effective parkour techniques depend on fast redistribution of body weight and the use of momentum to perform seemingly impossible or difficult body maneuvers at speed. Absorption and redistribution of energy is also an important factor, such as body rolls when landing which reduce impact forces on the legs and spine, allowing a tracer to jump from greater heights than those often considered sensible in other forms of acrobatics and gymnastics.