While overall intensity and the weight you lift are both important factors in hypertrophy or muscle growth, most people foolishly ignore another important factor... muscular contractions.
Muscle contractions describe the amount of muscle fibers or activity you can elicit from the working muscle during an exercise or set. By mastering this technique, you can quickly increase muscle mass and drive more stress into the target muscle, rather than dispersing the load over multiple muscle groups or joints that you aren’t even supposed to be training.
Enter Time Under Load
Time under load or, time under tension describes the amount of metabolic stress your muscle receives during a set.
Leading hypertrophy researchers have found that this is one of the 3 key factors involved in laying down new muscle. Sadly, 99% of people are completely omitting this mechanism from their training, which leaves a major opportunity to grow on the table.
To master time under tension or load, you must focus on keeping the working muscle under stress from the very first rep to the last. While you may think this is the case, it’s often not. Say you perform 10 reps, most people may only get 10-20 seconds of true time under load. This is around 30-40% of what we actually need, with research showing 30-40 seconds or more is the most optimal range to create metabolic stress.
Taking a bicep curl for example, if you perform 10 reps like most people, quickly driving the bar up, pausing for a second and then letting it drop down, you may only get 10 mini, one section muscular contractions during that movement.
You see, pausing at the top or bottom removes all time under load. While you are still holding the weight, the target muscle (in this case the bicep) is not being forced to contract under large amounts of load.
Therefore, even though your set may take 30 seconds, only 1/3 of that time is when the biceps are fully contracting or in theory, actually being worked to grow new muscle tissue.
How Metabolic Stress Works
Now you’ve got an overview of time under load or tension, here’s a breakdown of the science explaining why optimizing your muscular contractions and time under load is vital to optimize growth.
The main mechanism behind metabolic stress is the effects its has upon muscle protein synthesis. This is the biological action behind growing new muscle fibers. No muscle protein synthesis = no growth.
Metabolic stress is a potent stimulator of muscle protein synthesis, caused by the “pump” or burn you’ve likely felt when working out with high reps or advanced schemes like DTP. This pump forces the cells to expand, almost like a balloon about to pop. This then causes a form of ‘healthy’ damage, signaling to our body to adapt and become strong to cope with this stress.
In turn, our body decides to grow the muscle fibers and cells which it hopes will avoid further issues. Little does it know we will be heading back to the gym in a few days to do it all over again. This basically describes the long-term process of overload and muscle growth.
Metabolic stress also benefits your physique in other ways, such as enhancing lactate levels and growth hormone, a potent anabolic hormone. Compared to less metabolic workouts, higher rep or higher time under tension has been shown to more than double growth hormone levels, which can also elicit responses on a cellular level to help you grow and burn fat.
How to Improve Your Contractions and Metabolic Stress
Now you’ve got plenty of background info on its importance, it’s time to put the theory into practice and optimize your training for maximal growth.
Here are some key rules you must stick too, if your main goal is to optimize muscle growth and recruitment.
1. Pick the right weight:
Always pick a weight where you can complete the prescribed amount of reps in good time. While “cheat’ reps can be beneficial for those who are advanced, most do not master the basic form or movement first.
2. Pre-engage the muscle:
By pre-engaging the muscle first, you are more likely to maximize the muscle fiber recruitment during that exercise. For example, with a bicep curl, you may imagine you are doing a double bicep pose or tensing your bicep, before you even focus on driving up or lifting the weight.
3.Slow the Tempo:
Tempo describes the speed at which you perform the movement. By slowing down the movement speed, you can focus on using the working muscle for the whole lift, rather than using momentum and other supporting muscles to move the weight from A to B
4. Don't Pause:
As discussed, the importance of constant tension should not be overlooked and my good friend Ben Pakulski’s entire muscle building system is based on this factor. Every time you pause at the top or the bottom of the weight your muscles will lose this tension and metabolic stress. Furthermore, your brain will then have to try and send signals around the nervous system to get the target muscle re-engaged. By keeping constant tension, you can quickly overload that target muscle to cause large amounts of growth.
5. Picture the movement:
Another great tip is to focus on the movement pattern of that exercise for the working muscle. By moving your limbs (i.e. the arms or legs) in the pattern which matches how your muscle shortens and lengthens you can quickly improve your technique and maximize the contraction. The best example of this is bicep and tricep work. Imagine your elbow by the side of the body and just move your hand all the way up and down. You will see this forms a circular like motion, which you should focus on when curling or doing a tricep extension, rather than focus on lifting up or down, like most people will.
6. Eliminate other muscles:
Another key factor is focusing on eliminating other muscles by stabilizing your core and body. This ensures the working muscle will carry the majority of the load or weight, rather than it being spread out over 3,4 or even 5 muscle groups. Taking a bicep curl for example, by tensing your core and keeping your shoulders pulled down and back, it eliminates any movement from the upper body or core, like you may see most individuals doing. While you may have to drop the weight down by 20%, the work on the actual muscle may be doubled, which is a win win.
7. Forget the load in your hand:
While most people focus on the weight or load in their hands or on the bar, this is only one factor into overloading a muscle. Taking a DB chest press for example, if you were to take the dumbbells out another 2 inch as you lowered, it would be say 20% harder. To do this well, you need less weight. While people think this is bad, it’s simply not the case. In fact, the total load or stress on the joint and chest muscle is more, despite you using less total weight. Anyone who understands lever lengths and force displacement will quickly see that the load in your hand is just one factor.
Increase your Contractions to Grow
As you can see, optimizing muscle contractions is an extremely important skill any bodybuilder must master, especially for more isolate or single joint-specific work such as leg extensions, curls, tricep work, flys, side raises etc.
Apply these principles, drop the weight and take 1 step back, in order to take 10 steps forward in the long term!