Please choose the correct ending to complete the given sentence: Sports and Fitness: [header] How to supplement your stretching routine with dynamic stretching [title] Do calisthenics as a warm up. [step] For example, instead of doing 10 to 15 minutes on a treadmill as a warm up, do a whole body calisthenics routine for half of that time. Do calisthenics for 5 minutes then go on the treadmill for 5-10 minutes.

Ending1: It will help you to develop the endurance and flexibility needed to perform different stretches. [substeps] You can also do the dynamic stretching routine if you prefer. Ending2: [substeps] Dynamic stretching involves putting your feet together, then moving back and forth between your feet. It is important to perform dynamic stretches for warm up stretches. Ending3: [title] Be flexible, focus on the stretching aspect only when you are warm. [substeps] When you have been inactive, do not focus on the stretching aspect of the movement, but on the movement itself. Ending4: [substeps] The length of time it takes to stretch a number of different muscle groups is dependent on their strength and individual workout needs. [title] Take a series of targeted cardio walks.

Answer format: ending1/ending2/ending3/ending4