The first part of a complete warm up routine consists of raising body temperature by doing some type of cardiovascular activity, at a low, steady state intensity. This can be a walk/light run on the treadmill (or outdoor), jumping the rope, rowing (rower machine), stair master, elliptical, stationary bike.
The second part of a complete warm up routine consists of performing active mobility drills (e.g. leg swings, Crucifix, hip openers), with the aim of increasing range of motion in order to prepare the body to perform optimally during the main training session.
This is a flow: the exercises listed are to be performed back to back, for one total round. This means that once you have done all the repetitions of the first movement, you directly move into the next, in a Yoga-style flow.
MOVEMENT (link to demonstration)
Crucifix (with or without stick)
Upward facing dog into Downward facing dog
REPETITIONS
5 each side
5 each side
repeat twice
5 each side
12
20 each side
15
as shown in demonstration video, based on movement
The last phase of a warm up routine takes place right before beginning the first exercise of the resistance training bout (usually a compound movement), and it involves performing some repetitions in a pyramid fashion, by increasing the weight at every warm up set until reaching the working weight for the exercise. This is because beginning an exercise directly with the working weight is not a wise choice: this increases the risk of injury, and the muscles and movement pattern are not properly fine-tuned, which can lead to poor performance, particularly in the first few sets.