Personally, when weight training, I advocate related static stretching immediately following an exercise (i.e. during rest between sets), such as a Latissimus Dorsi stretch following lat pulldowns.
If performed correctly, the exercise undertaken should allow for near full stretch and contraction of the muscle/s. Following warm-up sets and working sets, your muscles are at their hottest and, therefore, can be elongated (stretched) to a greater degree.
Stretching between and after sets of an exercise should prove advantages to help avoid stiffness and re-establish a normal (or greater) range-of-movement. With this in mind, they should also be included as part of your eventual cool-down.
This page is an extract from the bestselling book Gym Workouts: Maps to Success.