Neurological Strength Adaptations

By: Matt Cooper MS, USAW National Coach at Pursuit Nutrition & Training Center“He/she doesn’t look that strong”. This is a common sentiment I hear from thoseoutside the weightlifting/competitive strength world. This has not only been said about athletesI coach, but about myself as well. The general public typically associates physical strength withmassive men with traps up to their ears and biceps the size of footballs. While strength athleteswith such massive physical dimensions can display impressive feats of strength, cultivating alarge amount of muscle mass is not only unnecessary for increasing strength but can be flat outundesirable in a sport with weight classes.There is certainly a time and place for training for hypertrophy (increase muscle mass),however, when you’re trying to build as much strength as possible within a certain weight class,hypertrophy is not the goal, neurological strength adaptations are; training your body to useyour nervous system as efficiently and effectively as possible in order to produce greateramounts of force. In this article, I plan on covering the neurological pathways that governphysical strength, and some of the training methods/principles that are best for inducingneurological strength adaptations.

Neural Components in the Creating Muscular Force ‍

The central nervous system (CNS) is of vital importance in the exertion and developmentof muscular strength. It is the hub that activates muscular contraction via electric impulse. Howthe body uses the CNS in regards to strength performance must be understood and consideredwhen designing an effective strength program. It is a complex system of nerve tissues with thebrain and spinal cord being the two primary structures. A closer look shows a coordinatedsystem of neurons and muscles that are made up of what are called motor units.Each motor unit consists of a motor neuron in the spinal cord, from which extends a long axon that goes to amuscle, and branches off to innervate individual muscle fibers (Kraemer & Zatsiorsky, 2006).

_{a motor unit}

_‍Muscle Fiber Types‍

Above I talked about motor-units being comprised of a motor-neuron, an axon, and allof the muscle fibers innervated by the branches from that axon. It is important to know,however, that not all motor-units are created equal. Some are large and some are small. This isdependent on how large the motor neuron is and what type of muscle fibers that are innervatedwithin that motor-unit. The classification is simple: Fast twitch and Slow twitch.Within these two categories, there are three sub-classifications: Type 1, Type 2A, and Type 2B.Depending on the type of activity, your body will recruit the appropriate type of musclefiber. The speed and duration of the activity are what will influence the muscle fiber typerecruited. A simple example would be to look at different running events in track &  field.

The 1600 meter run (1 mile) would recruit exclusively Type 1 muscle fibers as there is not a lot offorce or relative speed required to run 1600 meters. Also, as you can see in the chart above,these muscle fiber types are very resistant to fatigue, therefore these fibers can work optimallyfor longer periods of time. Let’s look at the 400-meter run (one lap around the track). This taskcan take anywhere between 45 seconds to 75 seconds (Let’s assume for the sake of simplicity,that we’re talking about moderately to highly trained athletes). This falls into the “medium”range. Meaning, maximal force production is not achieved but it is still higher than mostoxidative activities that last several minutes. This is where we see a high recruitment rate ofType2A fibers. Lastly, let’s look at the 100-meter sprint. This is a physical task that requires ahigh amount of force and speed over the course of mere seconds. Here is where Type 2Bmuscle fibers are put to work. These fibers have a fast contractile speed and can produce agreat amount of force. Their resistance to fatigue, however, is very low, so these fibers can onlyperform optimally for a matter of seconds.

‍Recruitment

‍The amount of force exerted by an individual muscle is determined not only by theamount of muscle mass involved, but also by the extent to which individual fibers within thatmuscle are activated. This is called intramuscular coordination (Kraemer & Zatsiorsky, 2006).There are many different muscle fibers (fast and slow), innervated by many different neuronswithin a particular muscle. Let’s take a look at the different principles and pathways that areused an involuntary muscular contraction.The Size Principle: This principle states that during muscular contraction the CNS will work in asequential order. Small motor units (innervating Type 1 fibers) with a low threshold for forceproduction, are recruited first. Then, the demands for larger forces are met by recruiting largermotor units with higher degrees of force production. Therefore, the largest motor units withthe highest capacity for speed and force production are recruited last.[caption id="attachment_1660" align="alignnone" width="593"]

_{Here is an illustration of the size principle. In this image, the required force for the activity/exercise is low. Therefore, only the smaller motor units are recruited. If the intensity of the activity were to increase, it would require more force production, so larger motor units would be recruited.}[/caption]

‍Rate Coding:

This refers to the frequency of the motor unit’s repeated activation (Everett,2016). A higher frequency results in a stronger and more explosive contraction until the motorunit reaches its full contraction limit. This channel of recruitment is particularly important indeveloping explosive force production at intensities above 80% of your 1RM (Ma, 2018).

‍Impulse Intensity:

This simply states that as the load being lifted increases so does themagnitude of the impulse from the CNS. As the magnitude of the impulse increases, larger,more force yielding motor units are recruited. By consistently training under heavy loads, thebody learns to efficiently create larger impulses that produce a stronger and faster muscularcontraction.Synchronization: Typically, motor units within a given muscle are activated asynchronously, orin a staggered fashion. However, there is evidence that elite power and strength athletesactivate motor units in a more synchronized fashion (Kraemer & Zatsiorsky, 2006). Inconjunction with high-intensity impulses and optimal rate coding, a high level of synchronicityof the motor units is imperative for maximal muscular force. This is a skill that can be trained.

‍Intermuscular Coordination:

When we’re talking about the total amount of force producedduring a movement, as opposed to within an individual muscle, it is greatly influenced by theprecise coordination of many muscle groups (Everett, 2016). This concerted effort betweendifferent muscle groups to produce maximal force during a particular movement is often referredto as a “skilled” act. Meaning, intermuscular coordination can be optimized andimproved through training and practice. It is arguably the most important skill one can acquirethrough training for athletics. Vladamir M. Zatsiorsky succinctly summarizes this point bystating “The entire movement pattern, rather than the strength of single joints, must be theprimary training objective. Thus, an athlete should use isolated strength exercises, in which themovement is performed in a single joint, only as a supplement to the main training program (p.63).”

‍Muscular Strength Deficit: Your Hidden Strength Potential

‍As was just described, performing physical tasks that require high rates of forceproduction have a variety of effects on our motor units. However, research has shown there aremany motor units that athletes cannot recruit or fully activate, regardless of their best effortsto produce maximal force. This is called the Muscular Strength Deficit (MSD). Experimentswith electrostimulation have shown this hidden potential exists. Researchers have usedelectrostimulation on a variety of athletes, from un-trained to elite. They compare and contrastthe force production exhibited during voluntary contraction with the electrostimulation(producing a greater amount of force) and without it. The results show an MSD between 5 to35%, with elite athletes (highly trained) showing the lowest deficit. Below is an equation thatrepresents how MSD is quantified (Kraemer & Zatsiorsky, 2006).

100 (Force during electrostimulation – Maximal Voluntary Force)

_______________________________________________________

Maximal Voluntary Force

So why is this important to know? The existence of MSD shows that every athlete hashidden strength reserves. No athlete, regardless of how elite, will ever completely eliminate theexistence of MSD. One of the primary goals of heavy strength training is to teach athletes theskill of recruiting more motor units at an optimal firing rate and, over time, decrease their MSD.Contrary to popular belief, initial strength gains in un-trained athletes are not due tohypertrophy, but to the newly activated motor units that have been otherwise dormant, orinsufficiently stimulated.

‍Training Methods

‍All of the information above is useless unless you understand how to train for thedesired neurological effects. For the purposes of this article, we are interested in developingpure functional strength performance; achieving the highest possible power output. As I said inthe introduction, there is a time and place for hypertrophy work (i.e. falling into a new, higherweight class), and it is a vital part of strength development over time as larger muscles have amuch higher potential for force production. However, if you’re a competitive strength athlete,your primary concern is producing the greatest amount of force in your competition lifts withinyour weight class, and your training should reflect that (specificity).

‍Maximal Effort Method:

This method has been found time and time again to be the superiormethod in developing absolute strength. With this method, you train with the heaviest possibleweights, between 1-3 repetitions. This method has huge advantages in developing favorableneurological adaptations. Any MSD that exists is reduced, a maximal number of motor units areactivated through increased intensity of neuron impulses, optimal impulse frequency, and intraand intermuscular coordination are improved (Everett, 2016). Lifting at or near maximal efforton a regular basis in some way, shape, or form is the most effective method for creatingneurological strength adaptations.When it comes to this method however, there are some limitations to consider. First isthe higher risk of injury. In any sport, this risk exists. That is why this method should only beused with athletes who are trained and have a high rate of consistency in the technique of theirlifts. In addition, there can be a higher rate of physical and mental fatigue and increasedanxiety. Lastly, if your goal is hypertrophy, this method will yield little to no results in thatregard (Kraemer & Zatsiorsky, 2006).There are many creative ways to use this method and mitigate any potential negativeside effects (i.e. the strategic use of training maxes as opposed to competition maxes can limitthe amount of psychological arousal and therefore, prevent burnout). While using this method,you should be working with a coach who understands how to safely and effectively utilize thismethod of training. Work with a coach who has a firm understanding of periodization forstrength development and how to effectively incorporate the training principals of specificity,variance, overload, and fatigue management.

‍Repetition Method:

Quickly summarized, this method is characterized by exerting forcerepeatedly with a sub-maximal load until the athlete reaches near or complete exhaustion eachset. This method has been shown to enhance metabolism, induce hypertrophy, improvetechnical coordination, and increase speed strength (Ma, 2018). This method is great for theearly accumulation phases of a training cycle as it is higher in volume by nature. The biggestlimitation it has, however, is that it is not effective at improving absolute strength.

‍Dynamic Effort Method:

The focus of this method is speed. Moving the load as quickly andexplosively as possible. Maximal speed with light weight are the necessary parameters.Therefore, the dynamic effort method is not used for increasing absolute strength, but toimprove the rate of force development and explosive strength (Kraemer & Zatsiorsky, 2006).Speed is an important part of producing force (F = Mass x acceleration), and just like any otherphysical trait, it must be practiced.ConclusionAll of this explains how athletes who may be smaller, in terms muscle mass, can displaywhat may seem like impossible feats of strength, and athletes who have large amounts ofmuscle mass can be weaker than you would expect. Training for neurological efficiency is thekey difference here. An athlete, who strictly trains for hypertrophy (10 or more reps every set),most likely has a very large MSD. They may still be seeing strength gains, but their fullneurological potential is not being met. Their largest, fastest, and most forceful motor units arenever being activated because their training demands never require it.All of the training methods described above are useful and should be used in some wayshape or form when training athletes; however, it is important to understand the what, when,and why. Randomly using, mixing, or negating any of these methods without a clear idea ofwhat the optimal training stimulus is for your athlete and the goals you both have set (i.e.peaking for an important meet), is an exercise in futility. Random programming will yieldrandom results.When training an athlete to become more neurologically efficient, they need to learnhow to recruit the most motor units possible (slow and fast) by creating impulses at the highestintensity and frequency possible, in a synchronized fashion. This is all achieved by training atvarying levels of resistance using the three methods described above. It is clear, however,repeatedly exposing an athlete to maximal or near maximal loads (assuming they’re properlytrained) is the most effective at helping an athlete achieve his or her full strength potential. Aspreviously stated, when you understand the what, when, and why in regards to these conceptsand methods (through research and experience), you’ll have a great foundation andprogramming repertoire to build from.

_{Matt Cooper MS, USAW National Coach at Pursuit Nutrition & Training Center}

_‍ReferencesEverett, G. (2016). Olympic Weightlifting: A complete guide for athletes and coaches (3rd ed.).Catalyst Athletics.Jianping, M., & Buitrago, M., Ph.D. (2018). Chinese Weightlifting: Technical Mastery andTraining. First Printing.Zatsiorsky, V. M., & Kraemer, W. J. (2006). Science and Practice of Strength Training.Champaign, ILL.: Human Kinetics.