There’s more to working out than simply selecting your weights. Speed or tempo training also has an effect.
In some circles, tempo training—also known as time under tension (TUT) or “slow training”—is considered to be the pinnacle of how to increase muscle size. Tempo training is often indicated by the following series of numbers: 4-0-1-0 or 4-0-X-0. The first number represents the eccentric action or muscle lengthening, the second number is the length of pause or isometric hold, the third number is the concentric action or muscle shortening phase, and the fourth number is another isometric hold or rest. In the case of an “X” in place of the third number, this represents an explosive action.
Let’s take a look at how these numbers affect a barbell back squat. You would lower the weight to a count of four, and once at the bottom of the squat, there would be no pause since the second number is a zero. In the first set of numbers, the lifter would rise up out of the squat to a count of one, but would explode up if they were following the second protocol. Finally, the last number represents the pause or hold at the end, which in this case is also zero.
If this were confession, I would be the first to ask for forgiveness. I, like many others in my industry, have been fooled into thinking that using a slow tempo for both the eccentric and concentric actions of a lift produces a greater hypertrophic response. Phew, that’s a load off. The research doesn’t quite suggest this outcome when volume (weight x reps x sets) is matched.
It’s worth noting that many, if not all of the studies on tempo have been completed using only untrained individuals, therefore the results may differ when looking at trained subjects. However, with the current research, the studies show repetition speed does not produce a statistically significant change in hypertrophy either way, but if you are counting at home, a slight edge does go to a faster repetition speed. Since eccentric action causes the greatest amount of muscle soreness, we often relate how sore we are the next day or two after training to the amount of hypertrophic gains, but unfortunately this really isn’t true.
The “Real” Factors Involved for Building Muscle?
Volume is the main factor to be considered with regards to hypertrophy. However, just to be clear, it isn’t the only factor, and this is where tempo training or TUT along with metabolic stress (lactic acid buildup), autocrine adaptations (IGF-1 and its variants), and muscle damage come in to play.
Tempo training does have its benefits in that it’s great for older populations and novice lifters to be able to fully control a weighted exercise. Slower eccentric and concentric actions are also great for those who are returning from an injury. A pause rep, which obviously increases the time under tension, is beneficial for cleaning up technique flaws and busting through sticking points.
Even though I know now that time under tension isn’t the main factor in hypertrophy, I still like to use a 4-0-1-0 tempo for all compound lifts such as deadlifts, squats, and presses and a 3-0-1-0 tempo for auxiliary exercises like curls, extensions, and raises. These tempos help me control the weight and maintain good form throughout the exercise.
Train hard, but train smart!