Neural Adaptations and More

February 1, 2016

It is interesting to think about observable physiological changes caused by resistance training. Time and time again I see and hear individuals speak of the "gains" made from lifting some weights. Most people do not understand the underlying processes taking place at a cellular level within the body. This leads to most individuals speaking of making immense gains in size and strength of their muscles after just working out for a few weeks.


Where am I heading with this? Well, increases in muscular size, as well as improvements in strength are not as quick as one might expect. It is all too common for an individual to either start, or return to an exercise regimen after an extended period of being sedentary, only to marvel at how big their muscles are getting, and how much strength they are experiencing.




First of all, let's discuss muscle hypertrophy, or the increase in size of your muscle cells. The "pump" individuals experience from higher repetition resistance training is known as "transient hypertrophy." Basically, this means an accumulation of fluids in the muscle cells, giving them the feeling of being swollen.


Transient hypertrophy is both a short-term as well as a long-term adaptation. In the short-term, muscles may feel “pumped” following a workout. Short-term transient hypertrophy doesn’t last very long, so if you are heading to the beach, workout immediately prior to leaving rather than the day before so that you can keep that bigger look.


Long-term transient hypertrophy is a training adaptation due to consistency. The more you workout and use your muscles, the more glycogen (sugar) and therefore water your muscles will suck up and retain as a reaction to being worked. If you know you are heading out on a long road trip (workout), you are more likely to go fill up your gas tank prior to leaving (glycogen/water retention).


A measurable increase in muscle size won’t actually be witnessed until at least 16 workouts into a resistance training program.* What’s the difference? Well, previously I discussed the increase in size due to water retention. That is like filling up your house with water. Sure, the over mass and density of the house has increased, and you may even get a bit of swelling, but the structural framework of the house hasn’t changed.


If, however, you are consistent with your training, once you reach that 16 week mark, then the muscles begin to increase in size structurally by adding structural proteins. To use the house analogy again, the construction crews then show up in 16 weeks to start adding that addition to the house you’ve been working so hard for - assuming you have the correct building supplies: i.e. hormones, protein, sufficient calories, etc.




Another observable and motivating symptom of resistance training is when an individual gains more strength. It can be an intoxicating feeling knowing that you are getting stronger. However, experienced strength gains witnessed by a beginner to a resistance training program are not necessarily what they think they are.


We sometimes perceive our muscles as self-controlling structures that abide by an "all or none" mechanism. This is simply not true. Your muscles are made up of muscle fibers, none of which are thicker than a strand of hair. When your muscle contracts, the entire length of the muscle shortens, however only a small percentage of the muscle fibers contract at any given time.


For example, if you were to pick a pencil up off of a table, a very small percentage of your muscle is actually doing the work to move your arm. However, if you were to be picking up a ten pound weight, more muscle fibers need to be "recruited" in order to lift the weight.


Muscle fibre recruitment is orchestrated by the muscle’s neurons. One, often overlooked, positive adaptation to resistance training is the improvements in your mind to muscle connection. Basically, your neurons greatly improve their efficiency at "recruiting" muscle fibers.


In other words, when you first start training, it may require 50% of the muscle fibres in your biceps brachii to curl a 30lb. dumbbell. However, as you get stronger, your muscles become more efficient and only require 40% of the muscle fibres to contract in order to curl the same 30lb. dumbbell. This not only improves the overall efficiency of the muscle, allowing you to complete more repetitions, but it will train you to be able to recruit more and more fibres to lift more and more weight.


During the first 8 weeks of a resistance training program for a beginner is the improvement of said neural adaptations.** So, even though one may be experiencing strength gains, this is not due to an increase in muscle size or any measurable improvement in the strength of the muscle itself, instead, it is an improvement in the efficiency of the mind to muscle connection. Your brain is getting better at telling your muscle fibres what to do!


What does all of this mean?


For the average person, this should be a convincing argument towards practicing a lifestyle of consistency, especially when it comes to physical activity and resistance training. By going through constant cycles of activity and inactivity, your results will be mostly limited to neural adaptations.

If, however, you wish to gain muscle mass and/or strength, it should be of your best interest to stick to a consistent schedule in order to improve your neural adaptations and beyond.


On the flip side of this argument, and for those who go through periods of inactivity due to injury, etc. remember that strength gains return faster to those individuals who have used resistance training previously. Not only that, but your muscles tend to return to a state of previous strength level in a much faster period of time.




*Staron, R. S., Karapondo, D. L., Kraemer, W. J., Fry, A. C., Gordon, S. E., Falkel, J. E., Hagerman, F. C., & Hikida, R. S. (1994). Skeletal muscle adaptations during the early phase of heavy-resistance training in men and women. Journal of Applied Physiology, 76, 463-475.

**Moritani, T., & deVries, H. A. (1979). Neural factors versus hypertrophy in the time course of muscle strength gain. American Journal of Physiological Medicine, 58, 115-130.


Tyler Robbins B.Sc., CSCS
Director of Fitness
Head of CrossFit

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