Leg Muscles: How Do They Work?About Your Leg Muscles The gluteus medius, gastrocnemius, rectus femoris, blah blah blah… What is all this stuff? Knowing what your thigh and leg muscles are and how they work is critical to understanding why in the world you do the thigh and leg exercises in the first place! I won’t beat around the bush here, so let’s get started with the thighs! The Abductors Many people get the abductors confused with the similar term “adductors.” They’re different! Basically, abductors are muscles that generally pull away from the body. For example, lifting your arm straight up to the side would be an example of “adducting” your arm at the shoulder joint. Basically, anything causing a limb to move away from your body is abducting. So, how about those abductors? These leg muscles (technically thigh muscles) lie on the outside of your thigh and work to pull your leg outward (or laterally) as in kicking a soccer ball sideways, pushing off on roller blades or balancing your body on one leg. The main muscles involved here are the gluteus medius and gluteus minimus. How do they work? It's important to understand where these leg muscles attach. Gluteus Medius To gain an understanding of how the gluteus medius works, let’s take into account where the muscle attaches. In general terms, the muscle arises from the back side of your pelvis (near an anatomical landmark known as the iliac crest – where you put your hands when you’ve got your hands on your hips) and inserts into a location called the greater trochanter at the top of the femur. It’s set up as a sort of hinge – when the muscle shortens, the thigh is abducted. Gluteus Minimus Similarly, the gluteus minimus is the smallest thigh abductor and lies underneath the gluteus medius. The muscle generally does the same thing, although its attachment points are slightly different – this one attaches underneath the gluteus medius and to a similar location on the greater trochanter (on the femur). The Adductors These muscles are directly opposed to the abductors, lying on the inside of your thigh. You may have already guessed that their main function is pull your leg back towards your body from the abducted position. Also, because their action is opposite of the abductors, it’s easy to understand that the muscle attachments will also be somewhat reversed. In the case of the adductor muscles (the adductor magnus, longus and brevis muscles along with the gracilis muscle), all attach to the inside and back of the upper thigh and leg. So, when the muscles contract, the leg is pulled back towards the body. There’re plenty of exercises to work this group of leg muscles! The quadriceps (quads for short) is a group of four closely-associated leg muscles covering the front of the femur that work to extend the lower leg at the knee (a.k.a. straightening your leg!). These muscles are absolutely critical for any sort of movement such as walking, running, jumping, squatting and kicking. The four muscles that make up the quadriceps group are the vastus lateralis, vastus medialis, vastus intermedius and the rectus femoris. They originate from various portions of the femur and attach to the knee cap (patella) via the patella tendon. A pull from these muscles results in the extension of the knee and/or flexion of the hip. Flexion of the hip is an important aspect of the quadriceps that is often overlooked. Because the main quadriceps muscle (the rectus femoris) is actually attached to the lower portion of the ilium (the side of the pelvis), the muscle is also important for flexing the thigh at the hip. An example would be lifting your leg to walk up a flight of stairs. Hamstrings The hamstring muscles directly oppose the action of the quadriceps and are often weaker. This can become problematic, especially for sports that require quick starting and stopping, such as in baseball and basketball. Because your quadriceps are the main actors in a sprint, your hamstrings are used to stop the forward motion. But, if you’re hamstrings are weaker than the quadriceps, excessive strain results! This is actually how I ended up tearing my hamstring at the very beginning of a 60 yard dash. The strength of my quads overpowered that of my hamstrings. Not enough leg and thigh exercises! The hamstrings (a.k.a. hams or hammies) lie directly opposed to the quadriceps on the back of the thighs. It’s kind of like a biceps muscle for your leg (the biceps femoris is one of the main muscles of this group). In short, the hamstrings flex the knee (or brings your heel towards your thigh. It’s easy to see how the quads and hams work together in walking, running, jumping, sprinting – when one works, the other relaxes and vice versa, just like your arms! And now let’s talk about the lower leg muscles! Just as a side note, the word “leg” only refers to everything below the knee! Everything above the knee is the thigh. Not the “upper leg”! The upper leg would actually be located somewhere directly below the knee cap (patella). I use the term “leg muscles” to encompass both leg and thigh muscles just for ease of reading. Sorry, that’s just one of my pet peeves! Lower Leg Muscles Remember, the leg encompasses everything below the knee! The calves, ankles and little muscles of the foot (we won’t worry too much about these). Gastrocnemius (or gastrocs) That’s kind of a mouthful, but it’s just your calf muscle. You know, the bulge on the back of your leg? This one’s important for flexing the ankle as in getting on your tip-toes to reach the top shelf of your closet. Sometimes it gets antsy and you feel like bouncing your leg up and down (raising and lowering the leg by extending and flexing the ankle). Runners and cyclists usually have extremely powerful gastrocs (along with other leg muscles). The gastrocnemius originates from the back and lower portion of the femur and converges into a tendon with the soleus muscle (I’ll get to this one in shortly). This tendon then attaches to the calcaneus bone (the bottom of the heel). A contraction of the muscle (and a pulling on the tendon) will result in flexion of the ankle, as in pointing your toes. The calf is fairly prone to injury, so be sure you do your stretching! Cramps are also very common (a.k.a Charlie horse) and can be caused simply by overuse. Soleus Muscle This powerful leg muscle lies directly underneath (deeper and below) the gastrocnemius. Basically, the soleus helps the gastroc do its job when the knee is already bent. Remember the leg-bouncing when you get antsy? Your soleus and gastroc work together to perform this action. The soleus arises from the upper portions of the tibia and fibula and converges into a common tendon with the gastrocnemius. The tendon then inserts into the bottom of the heel. Because the soleus doesn’t attach to the knee, it can use its full force when the knee is bent as opposed to the gastrocnemius which attaches to the femur (above the knee). Pushing your leg against something while your knee is bent, standing and, in fact, helping force blood back to your heart are its main functions Tibialis Anterior With every action there’s an opposite action, right? Right! So, opposite of the gastrocnemius and soleus is the tibialis anterior which covers the front of your leg. This muscle is mainly used to extend the ankle (as in trying to point your toes towards the sky or tapping your foot to a good tune). Shin Splints Shin splints is a painful leg condition that’s become a hot topic in sports, mainly because the cause can sometimes be mysterious. The condition is most commonly caused by improper running form rather than an injury to one of your leg muscles. For example, landing consistently on your heels while running causes the tibialis anterior to extend rapidly (thereby flexing the gastroc and soleus more often). Because the soleus is attached to a type of connective tissue (called the interosseus membrane) between the tibia and fibula, excessive contraction pulls on this membrane, referring pain down the tibial nerve which runs down the front of the leg. What I’m saying is that this referred type of pain can sometimes mistakenly be thought of as a tibialis anterior injury, when actually it’s just improper running form. Correct the form (running more on the “balls of your feet” and increased flexion of the thigh) and the pain should subside. But, however, in the case of some track runners, the shin pain may actually be excess pressure on the tibia and may cause fractures that don’t often heal properly. Painful conditions like this should always be checked out by a doctor! Don’t ever settle for what you think it probably is – always be certain you’re doing the right thing for your body, or you may have to pay for it later.
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