End ranges include using the entirety of a muscle or full range of motion. Working in your end ranges allows for potentially more mobility, muscle growth, and strength. You might be thinking, well, that makes sense, right? Now, how do you work with it? Let's consider a muscle like the quads and an exercise like the squat. Depending on your mobility and strength, you may or may not get to those end ranges. You may be able to squat just above parallel, which although is not inherently wrong, you may not reap all of the benefits. This would be an excellent opportunity to review and address your mobility, whether it be in your hips, ankles, or somewhere else. I suggest placing a plate underneath your heels for an elevated heels squat to increase your range of motion. This will remove some ankle mobility from the equation and allow you to squat deeper. See the video below for details.
It might be a bit more obvious with squats, but other exercises and muscles are affected by this, too. Here are a few to consider: - Calf raises (stand with your toes on a plate/step and let you heels fall lower than your toes) - Lat pull downs and pull-ups (think about your scap relaxing completely between each rep) - Push-up (there's a reason some don't count it unless it's a push-up plus!) You could essentially apply these concepts to any exercise. If you're struggling to get full range of motion in an exercise, seek advice from a qualified trainer who can either provide you with the tools to increase ROM or an alternative exercise.