I have been having some major shoulder pain lately, so i have been trying to find ways to get through the pain and still continue my workouts. I know in the past i never took the time to properly warm up, maybe just a few quick reps. From what i have been reading, warming up the muscles before putting a heavy work load on them can help them perform at a higher intensity, and lead to bigger gains.
By increasing muscle temperature you increase the speed of muscle contraction, blood and nutrient flow to the muscles, and decrease muscle resistance. Warm ups also help release more oxygen into the muscle and calcium which gives stronger muscle contractions and leads to something called the Treppe Effect, which some how makes the muscle more pliable.
Also do not stretch before weight lifting, Research has shown you can lose from 5-30% of your strength by stretching. although daily stretching can help to prevent muscle injuries. So in short Warming up increases your body’s core temperature, increases blood-flow to your muscles, establishes your range of motion, and increases the secretion of synovial fluid, which lubricates your joints. I know for alot of people including myself this is often a neglected part of working out, which could make a big difference.