Altered Reciprocal Inhibition

Mastermind Weekend 1/16

Hey there!

I'm Tina

I’m the owner of Carrots ‘N’ Cake as well as a Certified Nutrition Coach and Functional Diagnostic Nutrition Practitioner (FDN-P). I use macros and functional nutrition to help women find balance within their diets while achieving their body composition goals.


An in-depth, 4-week reverse dieting course for women who feel like their metabolism has slowed down, think they might have hormonal imbalance and can’t lose weight no matter what they do.

What a blog post title. Altered reciprocal inhibition. It’s actually a pretty cool concept. I’ll explain in a minute!


Mid-morning, I headed to the gym for a workout. I started with a 3.5-mile run on the treadmill. I used the Option 1 workout to guide my run.

Option 1


Option 2


After my run, I went to a Body Pump class. During class, I made sure to squeeze my glutes after each and every squat and lunge since I recently discovered that this area is pretty weak on me. (Yes, I have a weak butt.) As I was doing this, I thought: altered reciprocal inhibition, and I wanted to tell you guys about it since a lot of you seem to like the SCIENCE on CNC.

From my NASM textbook:

Altered reciprocal inhibition is the concept of muscle inhibition caused by a tight agonist, which decreases neural drive of its functional antagonist.

I swear, it’s not that complicated. Let me first explain agonists and antagonists.

Agonist muscles are muscles that act as prime movers, or, in other words, they are muscles most responsible for a particular movement. For example, the gluteus maximus (your butt) is an agonist for hip extension. Antagonist muscles perform the opposite action of the agonist. For example, the psoas (a deep hip flexor) is antagonistic to the glutes during hip extension.

Does that make sense? Ok, good. Onto the altered reciprocal inhibition part.

Here’s an example: if you sit at a desk for 40 hours a week, you probably have a tight psoas (hip flexors). The constant contraction of your hip flexors muscles (agonist) can reciprocally inhibit the glutes (antagonist). This means the glutes tend not to “fire” (aka contract) as they should. This results in muscle imbalances (i.e. a weak butt) and potential injuries. To help with this imbalance, I want to increase flexibility in my hip flexors and strengthen the glutes.

Interesting, right? All of my imbalances and running injuries are starting to make a lot of sense!


This morning’s workout made me really hungry, so as soon as I got home from the gym, I whipped up a quick lunch. It was only 11:00, but, hey, when you’re hungry, you’re hungry.

On the menu: salad with walnuts and balsamic vinegar.

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And a turkey sandwich with melted cheddar and honey mustard on a whole wheat Bagel Thin.

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After lunch, I enjoyed a cup of coconut-flavored coffee with coconut milk and a piece of dark chocolate. It was a sweet ending to lunch.

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The rest of my afternoon includes an interview, studying for the NASM exam, taking Murphy to the dog park, and picking up Mal from the airport. Mal has been away all weekend, so I can’t wait to see him!



  1. That’s really interesting. If you don’t mind me asking, how did you discover that you have a weak butt? lol I feel weird typing that, but I’m just curious about discovering my own imbalances.

    P.S. I really like these science-related posts you’ve been writing. And your post about the proper way to foam roll…life-changing. 🙂

    1. Haha! You just want to hear more about my butt! 😉

      When I first started working with my running coach, he had me doing a bunch of glute-strengthening exercises, so I sort of knew back then, but never put it all together until the NASM workshop. I have really tight hips (and hamstrings) so it makes sense. What really tipped me off though was trying to do a crunch on a stability ball with my glutes engaged the whole time. I could barely do it!

  2. Lunch looks fabulous!

    And there’s nothing better than feeling like you have more of an understanding of those things! When I injured myself, understanding the how/why of it made me feel much better about it for some odd reason.

  3. Thanks for posting this! I’m in a Physiology course right now and we recently learned about agonist and antagonist muscles but discussed them mainly in terms of maintaining posture when at rest. It’s cool to learn how the same concept applies to exercise!

  4. Great post (even if it has a somewhat odd title!!) I totally know what you mean by the tight hip flexor thing. I was working to correct a muscular imbalance a while ago and part of this (in addition to stretching my hip flexors) included strengthening my lower back and glutes. Good luck studying this afternoon – sounds like you already know tons!

  5. I love the science behind exercise (hence my degree in it!!) This is a great way to explain it all, Tina 🙂

    Also, weight training has a lot to do with the mind as well–gotta think about squeezing the glutes to rise from the squats–this also activates the muscles : the glutes and hamstrings even more so. These things in turn aide in supporting the other muscles.

    This same idea of agonist and antagonist applies to the abs and the lower bacl. If YOU want strong, awesome/tight abs, you gotta work your lower back as well.

    Love your lunch idea!

  6. Hi Tina,

    I’m new to strength exercises (other than doing random pushups and tridips at home) and want a written plan that I can follow daily (something I can plan out on a notebook written from monday-sunday). I hate just choosing random things with no direction. A written plan would be great. But with results. Do you have a suggestion? write one out yourself for a full week?

    I’ve heard that “jamie eason’s 12-week live fit trainer ” is good and also the New Rules of weightlifting for women (but i can’t afford the book and can’t find it at my library). Any help?

    1. What about meeting with a personal trainer to get you set up on a program? A lot of gyms offer free intro sessions to new members. I’m not sure if you have a gym, but it couldn’t hurt to ask!

      There’s also a ton of workouts on my blog under Fitness including 6 weeks of Carrots ‘N’ Weights.

  7. I love learning this stuff too – it makes a huge difference when you can apply it to your own body and make sense of some of its injuries/ idiosyncrasies. We balance agonist/antagonist muscles and corresponding joints in yoga too – this morning I taught a class that focused on heart (chest) openers and back-bends so in order to the chest muscles to open and release, we focused on stretching and opening the quads. Fun stuff 🙂

  8. Interesting stuff! Thanks for the information. Isn’t it great to study something you love?

    I KNOW my hips are so tight because of my office job. I feel like my yoga classes only keep me from regressing rather than furthering my flexibility because the whole class is spent getting me back to like…normal. If that makes sense!

  9. This is why I love your blog! Thank you so much for the information you have been giving us lately. Well, all of the time really. 🙂 This has been so beneficial with some of the things that I am trying lately. It’s coming at the perfect time! Thank you! 🙂

  10. Thank you for the science, it is interesting stuff. But even more importantly, thanks for explaining it in an easy to understand way.

  11. I want to understand this, so, what does squeezing the muscle after the rep actually do?
    I’ve noticed that I’m super sore when I do squats, step ups, and lunges – probably from sitting in chair all day, but I’m trying to gradually get into them by not using weights for awhile at first.

  12. I had no idea treadmills had that option! That’s a wonderful idea. I’ll have to try that once my knee injury (presumably caused by some sort of weakness in the buttocks or antagonist muscle group!) is healed up.



  13. love the tid bits from your studying, and it reinforces the concepts for you to actually apply them to your routine and then discuss them on the blog! I study exercise science in school so lots of my classes are about this stuff!

  14. I have exactly the same thing. After doing a 9km run (1st run for me) 8 weeks ago, my left hamstring & leg have been sore ever since. I just been to physio who told me that I have leg issues because my butt is not strong enough. Went for my 1st run again yesterday morning & my hamstring feels super sore again. So upset about it as I have missed my running, especially since training hard to build it up as I am not a natural runner. Been spending a lot of time stretching and on the foam roller (thanks for the tips). You must be reading my mind lately, all the injuries i have you seem to have covered in your recent topics.

  15. I also am suffering from “weak butt” syndrome — I am in my 5th week of PT, while my “weak butt” is getting stronger (a ton of squats, lunges etc), my hip remains with pain. Any thoughts? —

    ps I am a huge bio-nerd so I like this post!

  16. I really need to get a tredmill! Crossign my fingers I get one for Christmas. Your turkey and cheese sandwich looks so good! I haven’t had a good turkey sandwich in a whil, I’m thinking it owuld be great for dinner with some hearty soup! Ok, I’m to hungry, I need to go eat breakfast!

  17. I have a desk job and a couple of years ago I noticed that my hips were getting very tight. After a visit to the doctor it turned out that one hip got locked up from lack of rotational movement from sitting all day. I’ve been working on strengthening my gluts ever since and it’s made a huge difference in my hips.

  18. I just featured this post today in a article about preventing low back pain. Thanks for a great summary on altered reciprocal inhibition!

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