The Science of Fast Training

Motor units make muscles contract. The more motor units you recruit, the stronger and more powerful you become... and consequently, the greater your gains.

Muscle physiologists discovered an important law of motor unit recruitment: the faster the tempo of an exercise, the greater the recruitment of motor units.

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 which lead to substantial muscle growth. What's the primary difference between walking and jumping? Speed of muscle action.

The proof is clear when you observe the lower-body musculature of a gold-medal 100 meter sprinter compared to a hair stylist (or anyone who stands and walks all day).


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.

The fast-fatigable (FF) fast-twitch motor units 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 faster 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, synchronization) all work together to enhance intramuscular coordination.

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 so many lifters move slowly during the concentric or lifting phase. Maybe because it's easier or maybe because they can "feel" the muscle working. Either way, it leads to inferior results.

If you want strength and size, learn to lift fast. How fast? As fast as humanly possible without compromising form.

The first characteristic of fast concentric training that you'll probably notice is a relative lack of fatigue. In other words, you should feel supercharged at the end of your workouts, not fatigued. That's a good thing!

My clients extol the benefits of fast training because they constantly feel motivated to train throughout the week. In fact, I often have to hold them back when training in this fashion because they feel they can train the same exercises the very next day.

Train fast and you'll feel like your nervous system is constantly revved up.

Female Bench

If you've been in the iron game for less than a year, start performing the concentric – lifting or shortening – phase as fast as you possibly can. Don't think about tempo. Here's what you do:

  • Eccentric (negative or lowering part of the exercise) = controlled
  • Concentric (lifting part) = fast!

Perform the lowering phase under control (1-2 seconds) before exploding the weight up with lightning fast speed. Merely adding this element into any training program will be enough to accelerate muscle and strength gains.

Fast concentric tempos lead to the greatest recruitment of high-threshold motor units that possess a huge potential for muscle growth and strength increases. It improves the factors that compose intramuscular coordination: rate coding and enhanced synchronization of motor unit firing.

If you've been inside the iron haven for an appreciable amount of time, my advice is a little different. Keep in mind three primary methods to accelerate strength and size gains through fast concentric tempos. They are:

1 Stretch-Shortening Cycle (SSC) Training

Utilize a 20X tempo for all lifts. In other words, lower the load for a full count of two seconds before immediately pressing up the load as quickly as possible. This method takes advantage of the stretch-shortening cycle that leads to greater force and power production.

As P.V. Komi stated in Strength and Power in Sport, "The purpose of SSC is to make the final action (concentric phase) more powerful than that resulting from the concentric action alone." (2) In other words, training your SSC improves your ability to develop incredible strength.

2 Dissipation of SSC Effect

This type of training is the antithesis to SSC training. Just like it's necessary to train in different rep ranges, it's also sometimes necessary to offset the SSC effect.

In order to offset the SSC, you should hold the load in the stretch position for four seconds. This will dissipate any stretch-reflex that's commonly known as the elastic potential of muscle. In other words, your muscles can store energy, much like a rubber band, and sometimes it's beneficial to negate this effect to improve strength and size.

The hypothesis behind holding the muscle before performing the concentric phase is to minimize any energy that's stored within the series elastic component (SEC).

Dissipation of this energy source could potentially force the muscles to work harder to perform the lifting phase (more motor units are recruited since elastic potentials are no longer available).

3 Resting the Load

The last example relates to the advantages of unloading a weight before performing the concentric phase. When a weight is unloaded between the eccentric and concentric phases, the elastic potential of a muscle dissipates. Therefore, it forces you to build starting and accelerating strengths.

Explosive strength consists of three important components: starting strength, accelerating strength and maximal strength. By unloading the weight between reps, you'll improve two of three vastly important strength qualities that build explosive strength.

In order to obtain optimal strength and hypertrophy training results, all three methods should be periodized throughout your mesocycles.


If you want to totally revamp your program, try the following program. It's based on research along with my own successes with clients in all walks of life. It works, and it works incredibly well for strength and size. Here's what you should do for six weeks:

    Day 1

  • Sets: 6
  • Reps: 3
  • Load: 6RM (rep max)
  • Rest: 50 seconds between sets
  • Exercises: Dips, Front Squats, Chin-ups, Leg Curls and Seated Calf Raises
  • Day 2 Off

  • Perform 10 minutes of medium-intensity aerobics, if desired. Rope jumping and jogging are excellent choices.
  • Day 3

  • Sets: 5
  • Reps: 5
  • Load: 8RM
  • Rest: 60 seconds between sets
  • Exercises: Flat Bench Presses, Deadlifts, Bent-Over Rows, Skull Crushers, Donkey Calf Raises and Barbell Curls.
  • Day 4 Same as Day 2

    Day 5

  • Sets: 4
  • Reps: 6
  • Load: 9RM
  • Rest: 70 seconds between each set
  • Exercises: Incline Dumbbell Bench Presses, Back Squats, Upright Rows, Close-Grip Bench Presses, Standing Calf Raises and Preacher Curls
  • Day 6 and 7 Off

  • (Perform cardio or HIIT on one of the two days if desired.)

* These exercises are excellent choices, but feel free to substitute with a similar movement.

For the greatest benefit, all three of the speed-training methods should be used. The following periodization works extremely well:

  • Weeks 1-2: Stretch-Shortening Cycle (SSC) training method. Tempo: 10X (That's a one second negative with no pause. "X" means to explode, to lift as fast as possible.)
  • Weeks 3-4: Dissipation of SSC method. Tempo: 14X
  • Weeks 5-6: Resting the Load method. Tempo: 21X

Increase the load 2.5% if possible. The workouts in this program shouldn't induce large amounts of fatigue. If you feel like you could perform half of the workout again, you're on the right track. Leave the gym fresh and motivated – the key to consistent success with weight training.

If you learn to train fast without inducing failure and excessive fatigue, you'll accelerate your hypertrophy and explosive strength gains.

Make science your new training partner.