Hamstrings: Explosive Power Muscles

Hello everybody and get ready to dive into one of my favorite muscle groups: the hamstrings. I’ll be honest with you, a lot of people are enamored with things like the abdominal muscles or the pectoral muscles, but me-I’m a posterior chain kind of guy. You can read into that whatever you want, and you’ll probably be correct-within reason of course. From the muscles that begin at the base of our skull all the way down to our feet, the backside of the human body is a beautiful thing. The other side of our body is often neglected, or at least trained with less enthusiasm than the front. When I see ripped calves, hamstrings, glutes, low and upper back, my respect for the owner of said muscles is multiplied. I know the work and deep down pain that one has to go through to etch detail into this side of our body that is built for raw power. As the title of this post suggests, I’ll be getting up close and personal with the hamstrings today, and again on Thursday when I will discuss the training methods available to us and I’ll go over a few of my personal favorites that are extremely effective for building power, mass and detail. If everyone is ready, let’s get started!

Our hamstrings are string like tendons that are felt on either side of the back of the knee. If you flex your hamstrings and feel around you’ll notice how accurate a description strings is, as that’s exactly what they feel like. It’s kind of startling just how fine and delicate this muscle feels. This is also the reason why you so often hear of this muscle getting injured. It is not exactly a big and durable muscle, and needs to be handled with much care. If trained for a cared for correctly, this muscle can have sling-shot like power. This is a muscle that always needs special attention with regards to stretching and proper warm up. I’ll get into some methods I like in the training portion of this two part series.

Those four muscles are the semitendinosus, the semimembranosus, and the biceps formis, both the short and long head. The biceps formis brings home the comparison that I always make to the hamstrings as basically being the biceps of the leg. Just like our arms, the triceps is the larger and stronger of the muscles of the upper arm, but the biceps play a major role in being able to utilize that triceps strength and power. The same goes for our upper leg. The quadriceps is by far the larger of the muscles and the more powerful of the two, but without equally balanced hamstring strength, those quadriceps will never see their true potential utilized.

All four of these muscles are responsible for bending our knee, but the short head of the biceps formis does not cross the hip. The short head of the biceps formis only crosses the knee joint and therefore is not involved in hip extension. On another note-just saying hip extension gets me all excited to share my favorite hamstring power, size and strength builder with you, but once again I’m wandering into territory best discussed when training is the sole focus(teaser alert!). As such, the semitendinosus, the semimembranosus, and the long head of the biceps formis are considered the real hamstring muscles as those three muscle cross both the hip and the knee, and shoulder the vast majority of the load when it comes to knee flexion and hip extension.

The function of the hamstrings is actually quite intricate, and as someone interested in the specific roles of the muscles in our body I feel it’s worth sharing with you. As you know I’m a big believer that in order to take our training to the highest level possible, a complete and thorough understanding of what is happening when we train is necessary. Otherwise you will just do what everyone else is doing, and from my experience following the herd is not the most effective way of getting the best results possible. Make sense?

While it would be easy to sum up the hamstrings function when we are walking, running, jumping, while having some responsibility in the controlling of the movement of our trunks, this is too broad a definition of their role for my liking. For instance, just saying the hamstrings are important in walking leads us to believe that they have a job to in the actual moving of our legs, when in actuality their job in that capacity is somewhat limited. The real part they play in walking is in the deceleration of the knee extension that is initiated by the quadriceps. If the hamstrings didn’t slow this down, the powerful quadriceps muscles would cause our knee joints to hyper-extend at every opportunity they havsto straighten our legs. This is why the balance of the antagonistic muscles of our body are so important to keep in balance with the agonistic muscles. Without the proper balance, function will be impaired and injury is just waiting for the right opportunity to rear its ugly head.

So in the interests of the thoroughness that I like to think you have come to expect from this corner of the internet, here is a detailed account of the muscles, or their pairings and their specific function. The semitendinosus and the semimembranosus are both responsible for the extension of the hip when our trunk is stable. They also are responsible for flexing the knee and medially rotating the lower leg when the knee is in the flexed position. Said another way, they rotate the leg inwardly when the knee is bent. The long head of the biceps formis extends the hip when we make our first motion to begin walking. Both the short and long heads of the biceps formis cause the knee to flex and also facilitate the lateral rotation of the lower leg when the leg is bent. That last part put in simpler terms-the the outward rotaion of the lower leg when the knee is bent.

That is all that you need to know when it comes to the muscles of the hamstrings regarding their makeup and function. The real fun of course will begin when we get into the methods to stretch, train, and care for these somewhat delicate muscles that are also very powerful and strong when trained optimally. Some muscles seem to respond well to a good beating, and some respond best to kindness and care. The hamstrings are in the latter of the two aforementioned categories. Just because they require a little more tender love and care than say our quads, don’t underestimate their value to such things as a powerful deadlift, squat, or powerclean. The hamstrings are the muscle that is the glue in these lifts. Without them being as developed as the other muscles in play, the lifts I just mentioned will always be compromised.

When they are well developed and our body fat levels are low enough to allow them to be fully visible they are nothing short of stunning. A real work of art from a purely physical aesthetics point of view. When it comes to fitness competitors and bodybuilders of either sex, aesthetics is essentially the name of the game. Both disciplines are predicated on the presentation of ones physique, and if you want to truly awe both the judges and the audience, then a ripped set of hamstrings to set off that back pose is exactly what you need. Conversely if it’s power and strength you are after, you won’t get far without these muscles being in balance with the muscles of the front of your thigh. Whether it’s aesthetics or power and strength, balance is the key. Join me here tomorrow when I’ll be looking into the nutritional supremacy of another Low Carb Fruit,

Happy Lifting!


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