Flexibility and mobility are two terms often used interchangeably. People stretch and call it mobilizing, or say they need to “get loose” before a workout. I say the same things from time to time out of habit, but they’re not entirely accurate nor is “getting loose” before a workout as beneficial as you may think.
First, let’s define some terms:
Flexibility - this is used to describe the potential range of motion (ROM) that a given muscle has. If you lie on your back, grab your knee and hug it to your chest, you are stretching your glute and helping your hip achieve its full range of motion in that position. This is flexibility.
Mobility - this is used to describe how much range of motion a muscle has while also being able to produce tension. In the above example, we were trying to see how much potential range of motion you could get out of your hip. Now try to squat. Do you achieve the same position? Probably not, and that’s okay. When we add muscle tension to the equation, we usually lose a little flexibility. This is to keep our bodies safe, and is also why mobility is so important.
A flexible, lengthened muscle is not a strong muscle. If lengthened too much, a muscle is severely impaired in its ability to produce force. You may be able to get your body into great positions, but if you can’t produce force in those positions, what’s the point? In order to move, your muscles must contract and produce tension. This is how you walk, stand, squat, deadlift, etc. The ability to produce tension is also how you stay safe during these activities.
If you are trying to squat 400 pounds and lose tension in the bottom position, you may not be walking away from that lift. This is why “getting loose” or stretching right before strength work isn’t the best. In order to produce tension and lift big weights, our muscles need to be primed and ready to go. This means going through a dynamic warm-up that activates the muscle groups you will be using that day, increasing your heart rate, and adding in mobility work instead of static stretching. This will get your blood flowing and have you feeling ready to go. In addition, if you came in feeling stiff, this type of warm-up will allow you to move smoother than before. A warm muscle performs better than a cold one.
Without the ability to produce force in a given position, we risk injury. This is why it is important to train mobility vs. flexibility all the time. It’s all about control, and once you gain that control you can properly avoid injury and get even stronger.