The Balance of Flexors and Extensors.

        the balance of flexors and exensors      The balance of flexors and extensors

Our upright posture is largely determined by the balance of muscles known as flexors and extensors. A flexor is a muscle that draws two parts of the body closer to one another. Lifting your knee up to the chest is flexing the leg. When you walk and that same leg moves behind you it is the extension of that leg.

We can look at the front of the body being the flexors. Muscles that fall into the category are the quadriceps (not mainly a flexor but involved in the action), the psoas, the rectus abdominus (sit ups muscle). The back of the body are the extensors- gluteus maximus, hamstrings, erector spinea (spinal muscles that run up the back). This doesn’t mean that flexors can’t extend—they can and do. It is just that they have a primary purpose which is what we are looking in this post.

In the picture on the left we see a body that lives in a balance of flexion and extension. The front of the body is matched in length by the back of the body. The lower belly and the lower back are equally long. You can see the same relationship in the legs—the hamstrings and quadriceps live in harmony balancing each other nicely.

When we move to the picture on the right things get ugly. Not only do we have a body with poor posture but the relationship between the flexors and extensors has been thrown completely out of balance. Because of the nature of this bad posture, which is a very common pattern that I see in an overwhelming number of my clients, the flexors at the front of the body have become distended and are actually overly long with the appearance of extension. When the thighs lean forward of the pelvis, the quadriceps become over stretched (and they tighten full of tension as well), the rectus abdominis becomes overly long allowing the rib cage to lift too much in the front. At the back we have chronically shortened calves, hamstrings, erector spinea and quadratus lumborum to name a few.

To put it simply we have basically turned out flexors into extensors and vice versa. The balance of the flexion and extension is essential to achieving good posture and movement patterns. The essence of my work is to try and move people from being the picture on the right to becoming the picture on the left.


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  1. Thank you!
    This is a very easy to understand explanation of the importance of balance for posture and movement. This has helped me to understand why I stand the way I do and the need to fix this! Sue.

  2. Hi there, for me this has been a issue for over a year now, when younger I had done this naturally and as a result I had a naturally big butt and wide hip base, most would ask how and it must be gene from my mother … I already knew then, back then that it was not. I did things like squats without really knowing it I’d play games almost every morning and be squat in front of the tv for hours 2 at the most. This and I think the many hours of biking that me and my friends did for much of the day for many years of our lives would do this. It did for me, I’d always be on my legs working them out jumping doing something. I had huge legs. Now not so much… I had gotten complacent and sat for a lot of my years after high school was done and over with. I’d work go home be so tired I didn’t want to do much else but sleep… I found that work in itself was the key factor that had such a negative impact on me and my life, without it though, I’d have had no life. Therein lies the dilemma. I am a male, yes. I would have girls only my closest friend, she’d come up behind me and smack my behind and tell me it was so very big, this while was flattering it also somewhat embarrassed me. I thought this is something only a girl should have why do I have such a big bottom half my hips, butt and thighs. I started to hate the way I looked, they were all muscle, besides the normal fat content besides that they were just that. So into high school and that’s where it all began getting looked at for having such big mispositioned body, for a male. Must females liked, I didn’t as the guys would point or stare, say something like nice butt and laugh. It made me feel like I was a girl. My mom would just tell me that’s enough, you get it from me. I mostly agreed with this because I didn’t know and it made her feel good, important that maybe she did and after all it could very well have been true so why not. I later came to realize this was not how I should have handled this. I should have been honest with myself and told her what had happened and why, I maybe worked out this part of my body too much, in other words gave it too much attention… yes because I liked the way it looked. I know that is wrong, but I had sigh such amazing looking thighs and buttacks, yet I was ashamed for the most part… I am now getting those muscles reactivated and in motion some of the massive thigh muscle still lay in casual use. My friend was she a heavy girl and now she has transform her life and she is very skinny. I hope to reunite with her some day soon and ask her to be friends again. After her younger brother died… we drifted apart, her mom would often say things to her like he’s not of our culture… background, we didn’t mix. I had some of it in my family tree we had been friends since I can remember, before we were we lived across the street in a small harbour town, yet later in live not long after a short few years met again as young children it seemed that I would not be living my life nor hers without one another, our lives were as one it seemed. We were the best of friends, so that’s is another things that made it easy for her to want to be around me to not take what she said so critical all the time, eg, her smacking my butt and jumping on it.

    It is actually still as big as I ever remember it being “my butt” my hips and thighs those are a different story, I can not tell you the emase power… I had in those Thighs, I could do pretty much anything I wanted with them, for that I thank my mother she seemed to be right about that so I went with it and through length hours of training with he with a book known no other than the weights training for dummies … I gain these thighs and I stuck to it did them everyday if my body let me that was another important thing I had a strong sense of what I could handle and not at this age, I can not explain that further but I’m sure many children have this. So there was that, she helped me told me okay just one more you can do it she was a really big help, I know now she saw in me something, maybe a world athlete. I do not know as I am not. I have a bad side now maybe from inactivity.. I was a really good high jumper in high school apart from the kids that where faster being of less weight than me .. heh, I have always weighed around the same weight which I do not mind, It is a good thing. 180 around there, now I cannot tell as I have no scale, my dad has none, I live with my father.

    Well that is my “Story” so to speak… I hope to one day get this straight back I had in my legs, and make great use of it, lol i know that with great power comes great responsibility. I think that’s why and how i lost them i didn’t quite keep the latter… responsibility is a had mark to hit if one doesn’t know what to do. I had though in my childhood many friends that knew different areas of life, one exceeded in this area, though he liked magic and that ort of thing, always testing me he was. lol he was like my yoda, i know seems sort of odd, but he believed in the round table, the knights of old and as such i was bombarded with it daily on a constant. It was all fun and games though, for me that is. Now that I look back at it, maybe not so much for him. i don’t know. At anyrate those were two sets of friends divided apart by both little age difference and space he lived quite far and she down the road. I wish if someone were to see this and think to use any if all of it in a book you may, I’m a kind caring giving soul. It’s my story and that’s all I had to say. Thanks.

    D.A.B – B.A.D

    P.S. I’m keeping a copy just in case. 🙂 I truly hope this reachs the right hands maybe helps someone. These people in my life .. I would not have become who I am today without you.

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