I’ve been doing some reading on muscle hypertrophy and strength training in general, seeing that I work with young talent here at Kenako. I found a really nice article and this is the main information I gathered from it in a nutshell on this topic…

Until a few years ago, our scientists and the general public believed that strength was determined mainly by the muscles’ cross-sectional area (CSA). In other words muscle size or circumference. As a result, weight training was used to increase “engine size” – that is, to produce muscular hypertrophy. However, though CSA is the single best predictor of an individual’s strength, strength training research since the 1980s, have shifted the focus to the neural component of strength expression. In fact, the primary role of the nervous system in strength expression was well documented by a 2001 review.

 

Neural adaptations to strength training involve three things:

1. Disinhibition of inhibitory mechanisms

2. Intramuscular coordination improvements

3. Intermuscular coordination improvements

 

1. Disinhibition affects the following mechanisms:

• Golgi tendon organs – These are sensory receptors, located near the myotendinous junction, that elicit a reflex inhibition of the muscle they supply when it undergoes excessive tension, either by shortening or passive stretching.

• Renshaw cells – inhibitory connecting neurons (interneurons) found in the spinal cord, whose role is to dampen the rate of discharge of alpha motor neurons, thus preventing the muscular damage derived from tetanic contraction.

• Supraspinal inhibitory signals – conscious or unconscious inhibitory signals that come from the brain.

 

2. Intramuscular coordination are as follows:

• Synchronization – the capacity to contract motor units simultaneously.

• Recruitment – the capacity to recruit motor units simultaneously

• Rate coding – the capacity to increase firing rate (motor unit discharge rate) in order to express more strength.

 

3. Intermuscular coordination

This is the capacity of the nervous system to coordinate the “rings” of the kinetic chain, thus making the gesture more efficient. With time, as the nervous system learns the gesture, fewer motor units get activated by the same weight, which leaves more motor units available for activation by higher weights. I’d like to call it: long term adaptation to exercise.. Therefore, to increase the weight lifted in a given exercise over the long term, intermuscular coordination training (technique training) is the key. Nevertheless, intermuscular coordination is very exercise specific, so its transfer to other exercises (including sport-specific ones) is very limited. Even so, it remains the base for the athlete’s general strength development

 

Adaptations in intramuscular coordination transfer well from one exercise to another, as long as the specific motor pattern is established (inter-muscular coordination). For instance, the maximum voluntary recruitment of motor units developed through maximum strength training can be transferred to a sport-specific exercise skill as long as its technique is known by the athlete. The objective of maximum strength macrocycles is to improve motor unit recruitment of the prime movers, whereas power macrocycles work mainly on rate coding. Contrary to popular belief, these two aspects of intramuscular coordination – recruitment and rate coding – play greater determinant roles than synchronization does in muscular force production.

Source:  humankinetics.com

KeNako Academy, Strength Training and the Science Behind it, article.