Why Training Should Be Called “Braining” (Part 1)

Written by Heather

March 22nd, 2010

by Heather Morgan

Argh. Sometimes I’m like a dog with a bone on some topics. The Central Nervous System (CNS) has had me hot and bothered the last couple of weeks. But I did warn you in the post 2 weeks ago that it was a big topic. That was your heads up that there’d likely be more out of me. Then last week I got a little personal on the topic. Well this week—fear not—no personal diatribes. Actually, my shoulder injury will be mentioned, but just briefly, and only in context in the midst of some 1970’s geekiness. Promise.C
Bring out the disco ball, I’m citing some research that’s a few decades old today. While rehabbing my shoulder, I was reminded of a study and paper I did in college. While that Motor Learning class assignment was in 1992, I distinctly remember that much of the research my paper-partner and I found for it was…well…old. We were studying the effect of a balance task trained only on one side of the body’s transference to the other side of the body. We didn’t find much of the studies we based ours on in the newer sports medicine library, but, rather, in rehab and physiology journals in older libraries around campus. (Yeah, no internet. How did we even graduate? haha) At the time it was merely annoying and inconvenient to us, but as I think about it now what that tells me is that the sport science community largely ignored the research and hadn’t expounded on it much, at least not by the early 1990’s.
Anyhow, the shoulder deal reminded me of that project because it occurred to me that training effect transference has been proven and it happens because—say it with me, folks!—we only have one nervous system. So, while logic might lead you to believe that continuing to train one side of the body while resting the injured side might promote strength and ability imbalances, the opposite is actually true. The former “logical” thinking assumes that training effects such as muscle size increases due to training are what is responsible for improvements in strength and power, but that gives the muscles too much credit, at least for the first few weeks before muscle hypertrophy (size increase) is a factor. In fact, training is happening more so at the neurological level, with the nervous system rehearsing movements over and over which has many wonderful effects that appear “on the outside” as increased strength, power, speed, agility, balance, and dynamic flexibility. Just to name a few.
Okay, back to the ‘70’s. In a study from 1979, participants were to strengthen their elbow flexors on one arm only. What they found in that arm was that first the nervous system got better at recruiting more muscle cells to do the activity. Then the cross-sectional area of the muscles involved did eventually get bigger, which then contributed to some strength increases. But, the EMG studies still showed that it was neural adaptation contributing as well. The weird part is that eventually EMG studies showed that neural activation actually decreased while the amount of force associated with that lowered activation increased. Translation: It took less stimulation from the nervous system to get the muscle cells to produce a greater output. The nervous system was better at recruiting fibers for the activity, and the fibers it was recruiting were stronger. With some of those fibers now also bigger, the job of the nervous system to generate force production from the fibers is was recruiting was easier. This is why trained individuals find that over time activities that were a much bigger effort for them previously are now possible with less effort.
But here’s where it gets cooler and more relevant! The OTHER arm—the untrained one—got stronger too! In my own study I found this to be true with balance tasks. People got better at a one-legged balance task on their untrained side after practicing the task on the assigned side only. Most of the studies we used to support ours had to do with muscular hypertrophy and strength, like the one I just mentioned. In the 1979 study, the trained arm got 35% stronger while the untrained arm got 20% stronger. It certainly wasn’t because the untrained arm packed on more size. It was because the nervous system was able to take the patterns it used to improve the trained arm and translate it to the untrained arm. This gave me license to do things with my uninjured shoulder in hopes that my nervous system would layer that training neurologically on to my injured shoulder to avoid any large decreases in strength, and even mass, while I laid off of it for a while.
This is a concept that’s been used in the rehab world for eons, but it seems like only recently that it’s gotten hotter and hotter in the fitness and athletic training worlds, thus the resurrection of functional training, and the renewed sex appeal of compound movements, Olympic lifts, and kettlebell training. (By the way, this was just how people trained decades ago, it wasn’t called “functional training” as far as I know. It was merely “exercise”. Or, for some people decades before that, it was called “work” as they plowed fields, smithed metal, and so forth!) Speaking of more functional compound movements, another study looked at the effect of a specific training program on other activities. Participants were trained in the barbell squat for 8 weeks, increasing their strength in that movement pattern by 70%. Researchers then tested the participants’ strength during non-trained activities. The squatters improved in strength on the leg press as well, but to a lesser extent than the squat. They didn’t improve in strength at all on the seated leg extension, though. So their quads were stronger but their nervous system showed no improvement in ability to activate the quads during leg extensions.
So, how can OLD news help you in your NEW training programs? Here are a few tips to wrap this up:
• Strength increases in one activity don’t necessarily translate to dissimilar activities/movements/exercises. And the more dissimilar, the worse the transference. So, if training for a specific sport, keep the training sport-specific.
• On the heels of the point above, you should train movements, not muscles. If you don’t concentrate on the former, you will not be training the nervous system as well, and therefore you will sacrifice potential strength gains.
• Unless your sport is done seated, avoid doing much of your strength training while sitting. Likewise, avoid emphasizing isolated muscle groups, and instead favor multi-joint, full-body movements. Even better, include a predominance of one-sided exercises to enhance nervous system coordination.
• Keep in mind that your “weaker” side is benefitting from the stronger side’s training as well. Your nervous system is making sure of that. Single-side training can promote this, while also allowing less-able limbs to get stronger without the more-able ones there to pick up their slack as much.

References:
Moritani T, deVries HA: Neural factors versus hypertrophy in
the time course of muscle strength gain. Am J Phys Med
58:115-130, 1979
Thorstensson A, Karlsson J, Viitasalo JH, Luhtanen P, Komi PV:
Effect of strength training on EMG of human skeletal muscle.
Acta Physiol Scand. 1976 Oct;98(2):232-6.

A good read:

Movement That Matters, by Paul Chek

Tags: CNS