Our joints are comprised of two or more bones coming together to allow a certain range of motion.
Some joint structures are more straightforward. Our upper thigh bone is shaped like a roundy bump that fits nicely into a circular opening on the side of the pelvis to create the hip joint. This simple structure contributes to the joint’s sturdiness and wide range of motion.
Other joints are less straightforward. Our feet have 26 bones and 33 joints which means that some bones are part of multiple joints on different areas of their surface. This complex structure contributes to our foot’s adaptability and dexterity. The foot can stretch, it can curl, it can absorb the shape of whatever terrain is beneath it whether that’s our shoe, a patch of grass, a tennis ball or a rocky hillside. Many bones and many joints makes all of this possible for the foot.
In whole, our body has about 360 joints. I say about because the body is a complex structure and getting an accurate number depends both on the individual’s skeleton and on defining all the variations in joint types. Some joints are designed to move a lot (like the shoulders and elbows), some joints are designed to move a little (the SI joint), some joints are designed to move never (joints in the skull). Luckily, we don’t need to have a nuanced understanding of all several hundred joints to be a good mover. We just need to understand our major joint structures and what their ranges of motion are.
Why Is Range Of Motion Important?
Range of motion is important to develop as part of a capable and adaptable body. Our joints are designed with certain ranges of motion as possibilities--the bones, ligaments, muscles, tendons and other connective tissue are all designed to support certain types of movements. When we train our joints to support these movements, we simultaneously train mobility, stability and strength. This is helpful both as a tool to rehab our bodies from current aches and pains, and as prevention to keep our bodies feeling great for as long as possible.
Each part of the body is designed to support different ranges of motion depending on the shape and structure of the joints and connective tissues. For this reason, we need to chunk the body into major joints structures if we want to learn what’s possible for each area. Keep in mind that what I’m about to share is but the smallest of introductions to this topic. I hope that this stirs your interest enough to continue your movement education and empowers you to assess current limitations and see what some possible solutions might look like.
The Feet & Ankles
We know that each foot has 26 bones and 33 joints. This makes many different types of movement possible. The toes are able to work independently from the ankle (try wiggling your toes and keeping your ankle still), but every other joint in the foot is directly connected into the ankle, which means the ankle and foot are often working together.
Here’s what range of motion is possible for the feet and ankles:
To lift and lower the toes
To curl and stretch the toes
To move the big toe independently of all other toes
To dorsiflex the ankle (draw the top of the foot to the shin)
To plantarflex the ankle (draw the heel to the calf)
Invert the ankle (lift the big toe side of the ball up to the inner knee)
Ever the ankle (lift the pinky toe side of the ball up to the outer knee)
If you tried all of these ranges while reading, you probably notice that you’re able to do at least some of all of this. And still, the likelihood is that--unless you train your foot mobility often--you are underdeveloped in most, if not all, of these areas. This is wonderful! It shows us what work there is to be done. Our potential range of motion ends when the joint can physically move no further because of its bone structure.
The knee is often referred to as a hinge joint because that’s its main function: it opens one way and then the other like a door. But the knee can also rotate when it’s bent. This is a very important function. It needs this adaptability because it sits between two very mobile joints (the ankle and the hip) and it needs to be able to support our body and distribute forces evenly.
Because of its hinge structure, most of us have a pretty good range of motion in our knee. If we can stand up with our knees straight then our knees are capable of fully extending. If we can bend our knee to the point that we can bring our foot up to our butt behind us (with our hip in neutral), then we have full knee flexion. It’s knee flexion that most of us need to develop. This is often achieved by stretching the muscles on the front of the leg and hip, and strengthening the muscles on the back of the leg to support the movement.
But because the knee also rotates, it’s also important to train our knee’s ability to support various leg movements so that the structure doesn’t over-rotate when the ankles and hips are in variously mobile positions. This can be accomplished by walking or running on uneven ground, playing group sports, practicing yoga with attention on knee tracking, etc.
The hips are a ball and socket joint created by the head of the thigh bone plugging into a socket in each side of the pelvis. The thigh bone, which is the heaviest bone in the body, acts as a lever to move the pelvis in various positions.
When we talk about range of motion in the pelvis, we are talking about what the thigh bone is doing relative to the pelvis. Here’s what movements our thighs should be able to do:
Flex (leg draws up from the hip joint towards abdomen)
Extend (leg draws behind the frame of the body)
Externally rotate (thigh bone rolls away from the midline of the body)
Internally rotate (thigh bone rolls toward midline of the body)
Abduct (feet step wide apart)
Adduct (feet step close together)
Depending on the shape of our thigh bone and our hip socket, each person will have a different maximum range of motion possible in the hips. Most of us are capable of developing our hip flexion to the point that the belly and thighs are completely touching. Hip extension is a bit more limited with most skeletons tapping out between 0-15 degrees. External and internal rotation will also be different for each person, with most of us able to develop quite a wide range. This is also true with abducting and adducting.
There are 26 or 33 vertebrae in the spine depending on who you ask. The spine is naturally positioned in 5 sections--the neck, the mid/upper back (any vertebrae with a rib attached), the lower back, the sacrum and the tailbone. Each section of the spine has a different and opposite curve, which acts as shock absorption in the framework of our body.
Each part of our spine is inherently more or less mobile with more or less range of motion possible. The neck and lower back are quite mobile and often require additional support on the front of the body to ensure they are well positioned throughout our day. The mid-back is less movable and less moved, which is why so much of spinal mobility is focused in this area. In general spinal mobility exercises look to distribute our spinal effort evenly throughout the spine rather than letting any one area dominate a particular movement action.
A healthy spine should be able to:
Flex (bend over the legs)
Extend (bend backwards)
Laterally extend (reach over to the side)
The shoulder joint is similar to the hip joint, except the round bulbous end of the upper arm bone doesn’t sit into a snug socket like the pelvis. It aches to a bone on the front of the chest (the collar bone) and a bone on the back of the shoulder (the shoulder blade). This wider arrangement of bones gives the arm much more range of motion than the hip. The tradeoff is that the shoulder is also more unstable than the hip.
When we train our shoulder mobility, we’re really looking to train the muscles of our chest, arms upper back and upper side waste (under the armpit) to support the range of motion. Our shoulder should be able to:
Flex (reach overhead)
Extend (reach down and behind)
Adbuct (lift up and out to the side)
Adduct (lower by our sides)
Externally rotate (upper arm bones roll away from midline of body)
Internally rotate (upper arm bones roll toward midline of body)
It should also be able to move in all different planes of movement--in front of the body, diagonally, off the side, behind to a diagonal, etc.
As with developing the range of motion for any joint, it’s important to train our shoulder’s ability to perform these actions without the help of the spine, ribs or pelvis. When we go to take an arm overhead, our body will adjust all of our joints based on what’s easiest to move at that time. This might mean that as the arm tracks overhead, the ribs splay forward, the spine arches and the pelvis spills forward. These joints have moved to help us achieve our goal of moving the arm overhead, but this doesn’t help us achieve our goal of developing our shoulder’s range of motion.
The elbows, like the knees, are mostly hinge joints. One of their major actions is to bend and straighten the arms.
And--just like the knee joint--there is also a rotational property to the elbow. The elbow can rotate the forearm about a full 180 degrees. Try hugging your elbows in by your side with your arms bent in front of you. Without moving your upper arms simply rotate your forearms so that your palms are facing up and then facing down. For most skeletons, it’s possible to turn the palm completely up and completely down with the elbows fixed in by the sides.
If you recall, the knee requires extra stability and training to protect its vulnerable rotational structure. The elbow may require this as well, especially if we’re using our arms to lift, pull, swing, carry or bear weight. In this case, developing our range of motion may mean our ability to hold joint positions strong as force is applied against them.
To develop our range of motion, we must ask ourselves: What is each part of my body designed to do, and what would I need to do to develop my body to be able to do those things?
If we are committed to developing our range of motion, we will be able to progress in any physical skill we’re interested in safely, we will feel capable and motivated in our bodies, and we will have corrected our aches and pains that are created from suboptimal positioning.
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