You can change the benefits of all kinds of exercises b changing the speed at which you do the different parts. (Eccentric, Isometric, and Concentric) You won't change the muscles by doing this, but you can change how the muscle adapts. If you are trying to prevent injuries, I prefer to use a 4,2,1 tempo.

Count to 4 while you are gong with gravity

The eccentric phase is the part of any exercise where you are controlling the lower, or while you are moving with gravity. Using my favorite tempo to prevent injuries, you would count to 4 in the time it takes you to go from the top of your exercise to them bottom, think squats. I lower slowly enough that I can count to 4 in the time is takes me to go from standing to the lowest part of my squat.

I do this because being able to stabilize your joints well is a great way to prevent injuries. Moving slowly as you go with gravity, sometimes referred to as a "negative", helps you build the control required to do that stabilization. Since our muscles can only pull, you are working the same muscles that will drive you back up later.

Count to 2 while you hold the low position

You are going to hold the isometric position for a count of two. This is the hardest part of the exercise. On our squat, this would be the bottom, but in other exercises, like a sit up, this position can be harder to find. Look for where your muscles have to do little work to hold you in position and you should usually be able to find where you should hold.

Holding this challenging position will let you strengthen the joint and protect it better when you need to. This will make it easier to absorb the a little more impact from a fall or bump.

Count to 1 while you fight gravity

You are going to move through the concentric phase relatively quickly. This is the part where you are fighting gravity and the goal is not to move slowly again with this tempo but you aren't exploding up either. If we keep with our squat example, you would just stand back up.

Here we get to train our muscles to fire after stabilizing which can be a challenge.

And, that is my favorite tempo to use when the goal is to prevent injuries. 4,2,1 will work together to strengthen those joint and help you absorb more impact.