The Science of Fast Training
Muscle physiologists have discovered an important law of motor unit recruitment: the faster the tempo, the greater the recruitment of motor units. This is important because the more motor units you recruit, the greater the strength and muscle gains you’ll achieve.
Our nervous system is designed with an inherent, orderly recruitment of motor units. In other words, low-force tasks such as walking around your living room do little to induce muscle growth. Why? Simple: walking requires very little recruitment of motor units.
Jumping and sprinting, on the other hand, induce huge amounts of motor unit recruitment that leads to substantial muscle growth. What’s the primary difference between walking and jumping? Speed of muscle action, of course! The proof is clear when you observe the lower-body musculature of a gold-medal 100 meter sprinter compared to a hair stylist (i.e., someone who’s merely standing and walking all day long).
The benefits of fast training are:
1. Improved High-Threshold Motor Unit Recruitment
Quicker high-threshold motor unit recruitment occurs with super-fast tempos since you improve the recruitment of the motor units that have the most potential for growth. What I’m referring to are the fast-fatigable (FF) fast-twitch motor units that possess Type IIB muscle fibers. These motor units are capable of inducing huge amounts of strength and hypertrophy increases.
2. Improved Rate Coding
Rate coding is also enhanced with fast training. This relates to a change in discharge frequency of motor units with faster tempos. In other words, the firing rate increases with increases in speed (power) production.
3. Enhanced Synchronization of Motor Units
The last scientific element improved with fast training is enhanced synchronization of motor units. As you increase the frequency of fast training sessions, motor units improve their synchronous activation during maximal voluntary efforts. This leads to more strength and enhanced neuromuscular efficiency.
The three aforementioned variables (recruitment, rate coding and synchronization) all work in concert to enhance intramuscular coordination. But I’m not finished yet! A few more advantages of fast training are:
4. Improved Intermuscular Coordination
When you apply maximal effort to a load (attempt to lift it as fast as possible), you’re improving your body’s ability to maximally activate many different muscle groups simultaneously. This coordinated effort enhances intermuscular coordination which, in turn, improves your strength levels.
5. Altered Muscle Fiber Characteristics
With a consistent execution of fast training speeds, the skeletal muscle and nervous system adapt by converting many slow-twitch (Type I) muscle fibers to fast-twitch (Type IIA and IIB) characteristics. This is another perfect example of the specific adaptations to imposed demand (SAID) principle.
I can’t even begin to name all of the misleading advice that’s been dished out by newsstand muscle magazines, but one of the biggest misconceptions is slow training. I don’t know why in the hell trainees think they should lift a load slowly, maybe because it’s easier to lift slowly, or maybe because they can "feel" the muscles working. Either way, it’s pure bullshit that leads to inferior results.
