Almost every exercise would include muscle contracting phase. Once I was curious about why the top athletes like LeBorn James could lift the heavy weight with his strong arms. Where his power come from? Of course, I know they have done lots of training to get bigger muscle. However, there must be something we can go further and detailed. That’s why I really want to share today topic of muscle contraction.
Why muscle contraction is essential? Because it focuses directly on stimulating fibers growth. The ideal contraction phase is that we can activate all the muscle fibers. From concentric to eccentric contraction, slow tempos or explosive repetition, these processes relate to muscle resistance, blood congestion, positive-muscular damage, etc. These are advanced keys to trigger simulation signals and expand our muscle fibers to cause muscle hypertrophy.
The concept of muscle contraction helps make clear about the picture of muscle growth.
Therefore, I would like to share what I’ve learned from various resources including this book, Strength Training Anatomy Workout II which is written by Frédéric Delavier and Michael Gundill. They are famous gym specialists you could easily find them in the internet. They’ve published lots of common gym technics for various level. This second version is about advanced strength training details.
Good at human graphic (picture)
(List of content)
- How muscle contraction works inside the muscle
- How muscle contraction urges muscle growth
- 4 types of muscle contraction
- Adjust the speed of muscle contraction
How muscle contraction works inside the muscle
In my lifetime, I haven’t thought about how exactly my arm works inside my muscle. It surprises me that this biology lesson is not boring.
Our human muscles can be separated into three parts which are Smooth muscle, Cardiac muscle and Skeletal muscle. What related in workout area is Skeletal muscle. We always called muscle, muscle, muscle in our daily life. Actually, it exactly means our Skeletal muscle.
- One of three major muscle types
- Combined by multiple bundles of cells
In these three categories of human muscle, only Skeletal muscle can work under our voluntary control. For example, we can control when to pick a pen, bite your chicken breast or lift a 15kg weight, but human cannot control their heart (cardiac muscle) and organs (smooth muscle) .
As we mentioned muscle fibers before, it is time to discover where are muscle fibers in our body. Yes, it is in your Skeletal muscle. Below picture shows you bundles of muscle fibers can compose skeletal muscles. Then, we look at a one bundle of muscle fiber and you could see it contains lots of cells too. These little muscle fibers would contract and relax when they receive the message from our nervous system.
Let’s roll it down, muscle fibers are composed by many myofibrils. You can see there are many dots in one muscle fiber, it is myofibrils and each one has one contractile unit called sarcomere.
A sarcomere includes thick myosin filaments and thin actin filaments which cause muscle contraction when they slide past each other.
Let’s stop here and make it superb simple before it is too complicated. Here is the reference video you could know the rest part of how two filaments work together.
In short, when myosin filaments and actin filaments slide past each other, the sarcomere would contract. When the sarcomere contract, the whole muscle fibers would contract. When the entire contraction is in unison. That’s how your muscles provide you the power to lift the weight.
How muscle contraction urges muscle growth
After recognizing how muscle contraction works, another thing it is very important to know is that we cannot produce new muscle fibers in our muscle. Our congenital factor would affect the distribution of our muscle fibers. Therefore, our objective is making our muscle fibers thick and stronger through different tactics such as muscle contraction.
Everyone has started from somewhere. I am not a person with excellent athletic genetic. However, I believe all of our hard work will be rewarded. It is no need to worry about genetic factor. Love your human body and let’s keep learning and practicing!
Come back to how muscle contraction can accelerate our muscle growth. There are 5 keys that could apply in our workout.
- The tension of muscle stretching
- The tension of muscle contraction
- The timing of tension
- Muscle burning
- Muscle pump
If you’ve seen this post about muscle hypertrophy, you would sense these keys are all about it. There are three main factors to cause muscle hypertrophy which are mechanical tension, delayed onset muscle soreness (DOMS) and metabolic stress. These three factors are exactly match above key points. Below would be an integration package of muscle contraction. Read it!
The tension of muscle stretching
When we are contracting a certain weight, our muscle would be forced to stretch. This contracting phase would create lots of resistance. One of the result caused by this resistance is getting large amount of cells injured (positive muscular damage).
Eccentric contraction is a great example to explain. When we work biceps curl, we lower our dumbbells slowly to create the resistance between the bearing weight and muscle tension.
Our muscle fibers have possibility to be teared during this resistance phase. The tension of muscle stretching is the strong signal to stimulate our muscle to growth. We know that the target of using adaptability weights is forcing our muscle injury and grow. This is why we need enough protein to recovery these injuries.
The DOMS would appear if our fibers get injured. People love this popular term and use the pain to determine their yesterday workout effort. However, we cannot just focus on DOMS to discuss about the effectiveness of our hard work.
The tension of muscle contraction
When our weights are overloaded, it is hard to contract for our muscle. However, our muscles need to survive too. They are forced to increase the power to handle the resistance. This contracting training is very effective to stimulate muscle growth.
We can use the method of progressively overload to keep increasing the weight. Therefore, our muscle will keep handling the pressure and adapt this difficult situation day by day. It means we are getting stronger day by day.
The timing of tension
The weight bearing is not the only factor to affect the muscle growth during workout. According the Kumar’s research (Journal of Applied Physiology 106(6): 2026-39), it showed that the heavier weight, which is about 90% of your muscle strength, is not the most effective way for bigger muscle.
The timing of tension is also a role for muscle hypertrophy. We don’t want to make only 1 rep with the heaviest weight. The repetition maximum is too low and the timing of enduring the tension would decrease too.
You could check this post to discover what repetition maximum is. It helps people set a goal and pick a suitable weight to control how many reps and sets they need to achieve in their workout schedule.
If you pick a light weight, which is about 20%-40% of your muscle strength, it would be too light. The timing of enduring the tension is long but the weight is not heavy enough to stimulate the muscle growth.
Therefore, we need to catch the balance between the weight and timing of tension. In Kumar’s research, it suggested that the weight which is about 70%-80% of your muscle strength is the best balance point.
This part is about metabolic stress in our body. Our muscle fibers would produce lots of elements when we keep working the maximum effort in it. Lactic acid would start accumulating. That can explain why we have a burning feeling after workout. It is the stimulation signal caused by chemical factors. It is different to just apply the DOMS or overload to reach the muscle growth target.
When we repeat a motion, our muscle would be congested because we keep making contraction. The pumping is a great feeling. The blood would provide the energy in our muscle and that is why our muscle would be bigger temporally after workout. It increases the score of your body appearance immediately!
The blood congestion would make the pump feeling in muscle, and the distance of our muscle fibers would be squeezed to closer too. It is a normal mechanical tension which limit our power. This signal of muscle growth is not strong enough than above key points because the pumping cannot tear our muscle fiber. Moreover, pumping exercises is especially suitable for muscle recovery.
Types of muscle contraction
There are 4 types of muscle contraction which are concentric contraction, eccentric contraction, isometric contraction and isokinetic contraction. Stretching is also counted as a contraction. Below we use biceps curl as an example.
When we lift the dumbbell toward our body, we can feel that the focused biceps would be shortened. Our muscle strength is stronger than the weight.
When we lower the weight slowly, our biceps muscle would be lengthened. The tension of muscle is less than the resistance.
We hold the weight at a constant length. We do not shorten or lengthen the muscle and the tension is unchanged. Our muscle strength is equal to the resistance. The still position would produce isometric contraction.
Usually, this contraction need machine to activate such as treadmill. During isokinetic contraction, our speed is fixed and unchanged. Moreover, the higher speed we adjust, the smaller resistance we afford. This contraction method is used as recovery exercise too. We need to adjust the proper training speed. The resistance given by the machine will change with the movement of the joints (the higher the speed, the less the resistance). Therefore, our muscles, joints and connective tissues (ligaments and tendons, etc.) will not overload.
Adjust the speed of muscle contraction
Before we change the speed of our contracting phase, make sure we’ve done properly with the normal process:
- We use 1 to 2 seconds for concentric contraction
- Lift the weight toward our body and hold the contraction about 1 to 2 seconds. Make sure the squeezing is great. It is an isometric contraction.
- Lower the weight slowly and finish the eccentric contraction.
Hence is the fundamental process of a contraction. We could try different tactics to make various combination. Each motion has unique result for muscle growth. There are two changes you could try.
- Super slow repetition
- Explosive repetition
Super slow repetition
Super slow repetition means we slow down the process of whole motion. Although the pressure to the muscle is smaller than the explosive repetition, there are advantages as well.
This contraction could reduce the damages to the muscle and joint and extend the timing of tension. It also could improve the situation of some muscle group which is hard to activate it. However, we do not need much of neural stimulation to finish the contraction. It is good to train some muscle groups which are easily get tired or you can plan a set of contraction among two set of explosive training.
When we execute the super slow speed contraction, it means we need about 10 seconds to finish the concentric contraction. In normal case, we only take about 2 seconds. And the reps in each set need to reduce to 3-5 repetition.
In the eccentric contraction part, just take 1 second to finish the contraction. It is unnecessary to spend time on it because the tension is not enough for muscle growth. 1 second make the eccentric contraction and move to the next rep.
There are two methods to lift the weight during concentric contraction in super low speed. One is the smooth type of contraction, lift it slowly and don’t stop and hold the weight.
Another one is segmented type of contraction. It is super recommended because the effectiveness is great, and it is easy to execute. When we lift the weight toward about 5 cm, hold it for 2 seconds. Then, finish the concentric contraction and pause again. It is ideal to pause about 5 times and hold about 2 seconds each pause. So, our muscle would under the tension for at least 10 seconds.
After few sets, our muscle groups will start tired and the pauses will reduce too. Then, we would come back to the smooth type of contraction with no pause and finish the rest.
Remember, we do need time to adapt different progressively overload training. Therefore, we must start with a lightest weight first when you apply the super slow repetition method. Once you feel good at the motion, you could increase the weight and beat down another challenge.
At gym room, there are lots of stable equipment which are suitable to achieve the super slow repetition training. Moreover, we can use single-joint exercise to be familiar with the motion, then we can apply complex exercise on it.
There is a criticism about some athletes who working too fast. Some said they are performing cheating move and they should slow down per reps! However, it probably is a misunderstanding because they might working the explosive repetition training. It definitely benefits the muscle hypertrophy if we work it properly.
Based on the prove of science from Japanese, the explosive repetition takes more effectiveness than super slow repetition. The research showed below results after using 8 weeks with these two methods for bigger arm muscle. Super slow repetition increases 10% of muscle volume and explosive repetition increases 15% of muscle volume. Let’s go further to explain why.
How explosive repetition maximize the muscle contraction
Here would introduce the term, electrical impulses to explain what are the advantages of explosion reps. Below has a simply picture to sum it up!
Just need to know electrical impulse is part of central nervous system. We use Herz(Hz) as a unit to represent how much impulses releases to the muscle from nerve ending.
When our impulses reach to the 80Hz, it means every muscle fibers are used to work. In this stimulation phase, we can finish about 8 reps before we are exhausted. It is related to repetition maximum. If your weight is too light, we cannot apply all muscle fibers.
When our impulses reach to the 100Hz, the intensity of fibers contraction increases. In this situation, our fibers provide us a power to finish 8 explosive reps. It means explosive reps that enable us to lift heavier weight.
When our impulses reach to the 120Hz, it is time to get the real feeling. It is the strongest voluntary muscle contraction in human body. It can enable our fibers to finish a set of maximum repetition reps with extremely explosion.
So, what if our nerve impulses reach to the 150Hz? It is the strongest signal without voluntary control. It appears when we are in spasm situation. Imagine if we can use 150Hz during the workout, our muscle would growth superb fast, but human cannot afford that pain.
Okay, someone ask for 200Hz. Relax, it is not about human area. 200Hz could use to describe some bugs. Their high muscle contraction frequency which enable them to fly. They have super, super, super fast muscle.
Let’s have a short conclusion, there are only 30Hz difference between voluntary muscle contraction (120Hz) and spasm (150Hz). This difference called strength gap because this range of strength cannot be activated during the workout.
Therefore, if we take super slow tempos, the strength gap would be more obvious. For advanced muscle growth, fast tempos could have more contraction stimulation. A rep slower than 6 seconds to finish is quite suboptimal.
Now we know explosive contraction gain so much benefits to grow muscle. However, everyone is different. An athlete can utilize explosive training because they have higher ratio of Type 2 muscle fibers (fast twitch fibers).
Usually, human body has 50% of Type 1 muscle (slow twitch fibers) and 50% of Type 2 muscle. The ratio is different for everyone. It explains why top athletes can achieve explosive training better than normal people.
From medical research, about 50% of muscle fibers is decided when we are born. The rest of 50% would be affected by acquired behavior. As I mentioned we cannot create new muscle fibers, but we can turn our Type 1 muscle fiber to our type 2 muscle fiber.
Explosive repetition is not recommended for everyone
For beginner, the first thing is to master and control the muscle contraction first. It is why we need to take it slow because our muscle adaptability is important. I’ve tried to make it explosively when I get started. About 4-6 reps, my body is naturally cheating. It is too soon to move to the explosive repetition. It has possibility to cause injury and affect our effectiveness. We all need time to practice from the basic!
Sometimes we lose the feeling of contraction. One of the reason is that the exercise is too explosive. If we cannot control the fibers contraction well, it means we lack fast twitch fibers in our muscle. Therefore, if we need to achieve super slow repetition in order to feel the contraction feeling, it represents our ratio of slow twitch fibers is higher than fast twitch fibers.
Whatever explosive contraction or super slow contraction, there are no one training method could apply in our whole body. If we do insist to take one method, each muscle group would have different reaction because each contains different ratio of type 1 and 2 muscle fibers.
To solve this problem, we can adjust our training method in different muscle groups. Some take explosive training, and some take slow tempo training.
Now, I know why LeBron James could make those crazy dunks and moves. Are you ready to expand your muscle fibers?
Hopefully, above could explain to you why muscle contraction is essential to build bigger muscle from concepts to application. The concept of contraction is suitable for beginners. It helps people pick a right weight and perform exercises with different variation. Recognizing the details of contraction make clear about your goals and workout scheduled. Let’s work it together!