Is It Necessary to do a Warm-Up Set?

When performing high intensity strength training using proper form and a slow, controlled speed of motion additional warm up sets are almost never necessary. In most cases they provide little or no benefit while wasting time and energy that could otherwise be devoted to the “work” sets.

Most of the physical benefits of a warm up – increased blood flow to the muscles, enhanced metabolic reactions, reduced muscle viscosity, increased extensibility of connective tissue, improved conduction velocity of action potentials, etc. – are obtained during the first few repetitions of an exercise. Additionally, each exercise performed helps prepare your muscles and joints for subsequent exercises they’re involved in.

People with some physical conditions or joint problems may find they tolerate certain exercises better or experience noticeably reduced joint discomfort if they perform a warm up set prior to exercises involving the affected joints or body areas. When this is the case only a single warm up set is required, and it should be performed with half or less of the resistance to be used for the work set to provide the previously mentioned benefits while wasting as little energy as possible. In some of these cases they can perform certain exercises better by first performing a different exercise that involves the same joints. 

👉 For example, your knees may tolerate exercises involving extension better if they warm them up with a knee flexion exercise, or maybe your elbows tend to lock during pulling movements and you find it helps to perform a pushing movement first.

One last thing.

It is often still recommend to add stretching as part of a warm up, however stretching prior to a workout does not prevent injury, and should not be performed since it can reduce the muscles’ ability to produce force.
Stretching is highly overrated and with a few exceptions there is no need to do it at all. 

Regularly performing exercises for all the major muscle groups over a normal range of motion will help achieve and maintain a functional, healthy level of flexibility adequate for the majority of activities a person would participate in. 

If stretching is performed at all it should only be performed after the workout.

Article Credit: Drew Baye, https://baye.com/warming-up