Mobility and flexibility are terms that people often confuse. Too many people think that flexibility and mobility are the same things but they’re actually two different entities that both relate to physical fitness. You can be flexible and not have good mobility and vice versa. Let’s define what each means, why they’re important, and how they’re different.
Flexibility refers to how “stretchable” your muscles are. It pertains to how much you’re able to lengthen a particular muscle. Being more flexible is beneficial up to a point. But, it’s possible to be too flexible and a lack of flexibility and too much flexibility both increase the risk of injury. If you lack flexibility, you’re at higher risk of straining a muscle because it’s too tight. However, being too flexible increases the risk of a dislocation.
Being excessively flexible, to the point that it’s a liability is called generalized joint hypermobility, or GJH. If you have this condition, the connective tissue, including tendons and ligaments, that support your joints and muscles are more elastic than normal. Sometimes, these people are referred to as “double jointed.”
Being “double jointed” means you can amuse your friends by bending your thumb back so that it almost touches your hand. Plus, it gives you the ability to do some pretty amazing yoga poses, but it may work against you as well. When you’re hypermobile or hyperflexible you routinely stretch and strain the connective tissue that surrounds your joints because you can move them beyond what is “normal.” Over the years, that takes its toll on these supportive tissues.
A more extreme case of hyper-flexibility and hypermobility is a condition called Ehlers-Danlos syndrome. This is an often inherited condition where connective tissue is so flexible that it leads to bigger problems, like chronic joint pain, a higher risk of dislocations, loose skin (due to “stretchy” connective tissue), easy bruising, excessive fatigue, and a higher risk of hernias and aneurysms. Fortunately, this condition only affects about one in 5000 people.
Flexibility Changes with Age
You were much more flexible when you were a young’un. That’s because we typically lose flexibility with age. In fact, research shows the average person becomes 5% less flexible with each decade. If you lack flexibility, you can improve it to some degree by adding stretching exercises to your routine and including yoga in your fitness routine.
But, stretching doesn’t work the way you might imagine. You lengthen a muscle through stretching, but it doesn’t stay elongated for very long. Rather it returns to its normal length. The likely way that stretching improves flexibility is by retraining your nervous system to not see elongation of the muscle as a threat. So, when you regularly stretch, it increases the tolerance of your muscle’s to being lengthened.
There’s also some evidence that foam rolling can improve flexibility by increasing blood flow to the muscle and decreasing its resistance to stretch. What is doubtful is whether foam rolling really breaks up muscle adhesions as it’s unlikely the force would be enough to do this. It probably exerts its benefits by acting on your nervous system instead.
How Mobility Differs from Flexibility
Mobility, in contrast to flexibility, refers to your body’s ability to move through a given range of motion. Whereas flexibility is the ability of muscles to lengthen, mobility involves the interaction of muscles, ligaments, tendons, the joint capsule, and input from the central nervous system. And, yes, you can have good flexibility and still have poor mobility as mobility involves an interplay between several structures and systems. Mobility is the ability to fluidly carry out functional movements without restriction. Yet, flexibility is one component of mobility, as tight muscles that won’t stretch reduce mobility.
Why Is Mobility Important?
If a joint lacks mobility, for example, your hips, you won’t be able to descend as low into a squat. Deeper squats may be out of the question and you won’t get the same benefits from the exercise that someone with good mobility might get. So, lack of mobility may limit your gains. In addition, lack of mobility in the hips and ankles increase the risk of injury.
Sitting Impairs Flexibility and Mobility
Sitting too much during the day can impair flexibility, especially flexibility in the hip flexors, and this, in turn, can impair mobility. Simply getting up and stretching and walking more throughout the day can help you avoid the problem of overly tight hip flexors. When your hip flexors are looser, you’ll have less problem descending into a squat.
Could your mobility use an upgrade? To improve overall mobility, you need stretches to improve flexibility and resistance exercises to strengthen the opposing muscles. When one group of muscles, like the hip flexors, are tight, the opposing muscles, the extensors, are often weak. It’s important to correct that imbalance. There is a variety of hip flexor stretches you can do for tight hip flexors as well as strengthening exercises for the opposing muscles, the glutes and hamstrings.
Also, make sure you’re including hip mobility exercises in your routine. A simple exercise is front and side leg swings. Ankle mobility is also a problem for many people. Simple movements you can do to improve ankle mobility are ankle dorsi and plantar flexion movements. To do these ankle mobility exercises, place one hand on a table for support. Now, flex your feet forward until you’re standing on tiptoes. Then, rock backward onto your heels. Keep repeating this movement until you’ve completed 12 to 15 repetitions.
It’s also important to do mobility exercises for your neck and shoulders. There are a variety of upper body mobility exercises that will do this. Finally, you can improve mobility by simply doing strength training exercises, like squats, through their full range-of-motion. If you can’t go all the way down into a squat at first, incrementally increase the depth that you squat so that you’re improving over time. Use lighter weights and work on using as full a range-of-motion as possible.
The Bottom Line
Flexibility and mobility are both important to optimize fitness and lower the risk of injury. If you’re deficient in either, devote a bit more focus to correcting the problem with mobility exercises, stretching, and, possibly, foam rolling. As you age, doing these things becomes even more important.
Med Sci Sports Exerc. 2014 Jan;46(1):131-42. doi: 10.1249/MSS.0b013e3182a123db.
MedLine Plus. “Ehlers-Danlos syndrome”
LiveScience.com. “Does Stretching Increase Flexibility?”
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