Adaptations from Concentric Muscular Contractions
Each muscle along with all of its elements right down to the smallest contractile unit of the sarcomere is capable of three contraction types: concentric, eccentric, and isometric. Each type comes along with its own set of adaptations that can be used strategically to procure the specific adaptations necessary to reach an athlete’s specific set of goals. These contraction types can be used together or separately to focus on particular adaptations, and it is these contraction types and their specific adaptations that we will discuss over the next few weeks. This week we will focus on the Concentric Contraction.
- Description of the Various Muscular Contractions
- Adaptations the Concentric Contraction Type might yield
- Specificities required of Concentric Contraction to yield specific adaptations
- Examples of Concentric Only or Concentric Focused Exercises
Muscular Contraction Type Description
There are three types of contractions possible for any particular muscle of the body. First, a concentric contraction is the shortening of a muscle that in turn pulls on the tendon that crosses a joint to the attachment point in the corresponding bone in turn causing movement. An example might be when the biceps brachii shortens and in turn brings the lower arm closer to the upper arm. An eccentric contraction is the lengthening of a muscle allowing for movement in the opposite direction. An example of an eccentric contraction is the biceps brachii lengthening after a biceps curl once again bringing the muscles to a lengthened position moving the lower arm away from the upper arm. Finally, an isometric contraction is one where the length of a muscle doesn’t change like in the isometric contractions experienced by the spinal extensors that maintain long term isometric contractions to allow humans to maintain an upright posture.
Adaptations from Specific Contraction Types
When we lift a weight, a muscle or more specifically a group of muscles shorten in what we now know is a concentric contraction. When we lower a weight, a muscle or group of muscles lengthen in an eccentric contraction allowing the joint to return to its original position. When we strain against a barbell or machine without producing movement, this is an isometric contraction due to the length of particular muscle not changing. Most of the time an exercise contains all three contraction types rendering some benefits from all three contraction types. However, once we realize the specific adaptations from each contraction type, we can also decide to target or emphasize a specific contraction type to yield more adaptations from that particular contraction. Therefore, let’s look at the Concentric Contraction adaptations a bit closer.
Specificities for adaptations for each contraction type
The principle of specificity is a principle that I will refer to over and over again as we make our way through this series on the adaptations from the various stimuli. The principle of specificity states that our strength gains are greater when the test is similar to the exercise used in training. Therefore, when we focus on concentric contractions, we get better at lifting weights concentrically. When we focus on eccentric contractions in our training, we get better at lowering weights. When we spend quality time focusing on isometric contractions, we get better at producing force without our muscles actually moving. The reason is due to the specific set of adaptations that come with each contraction type.
Concentric Contraction Adaptations
During concentric contractions, we experience two specific sets of adaptations. Concentric only contractions will elicit an increased rate coding or an increase in the rate of the signal from the brain to the various muscle fibers that each alpha neuron innervates. The other adaptation is an increased pennation angle(PA). Now I will explain the cause of each adaptation. The speed in rate coding increases due to a higher velocity experienced from concentric contractions which leads to a higher detachment rate of myosin-actin cross-bridges. This higher rate of detachment forces the brain to increase the rate of signal to allow for continued force production and more cross-bridges to take the detached cross-bridges place.
The PA increases due to the automatic increase of PA when a muscle shortens. Therefore, if a muscle experiences an increase in PA without the counter lengthening under load experienced during typical strength training, the muscle adapts with an increase in PA giving muscle fibers the ability to produce maximum force. Pennation angle is referring to the architecture of the muscle fibers in relation to the tendons. The muscle fibers can be arranged in parallel to the tendon or in series. Parallel architecture has several sets of muscle fibers arranged at an angle in relation to the tendon. If the muscle fibers are arranged in series, they are in the same direction relative to the tendon, and this arrangement of course comes with less total muscle fibers. A greater pennation angle is a stronger architecture because it has more muscle fibers attached to the longitudinal line of the muscle’s tendon, but that comes with a slower contraction due to the muscle fibers all pulling at the same rate. Basically, you have more muscle fibers, but it’s still the same rate of contraction. When you fit more muscle fibers into a muscle, they are shorter, stronger, but slower. In series, the muscle fibers are fewer creating a longer range of motion when contracted resulting in a faster contraction.
Examples of Concentric Only or Concentric Focused Exercises
There are several ways to take advantage of the possible adaptations from Concentric Focused exercises. I will show you a closer look at these movements in the video, but here are some examples:
- Deadlift, Snatch Pulls, or Clean Pulls– you can perform these exercises from the floor, from a deficit, or off boxes. We will go over range of motion in a few weeks, but simply put, shorter ranges of motion allow the athlete to use greater loads focusing on force production while longer ranges of motion allow for higher velocities due to impulse (force x time).
- Presses from various heights of pins– for a pure focus on concentric only contractions, you will need partners to lower the weight for you or complete singles and rack each repetition.
- Squats (Front or Back) Bottom Up– the athlete will need safety pins or blocks to put the bar at the height you choose. Once again we will talk more about range of motion in a few weeks, but some might choose to start at higher heights to focus on specific joint angle improvements.
For each of these, focus on lower reps and a greater number of sets for greater focus on velocity and technical improvements. I recommend using velocity to monitor improvements in overall velocity, but especially time to peak force. An improved rate of force development will render improvements in power and speed both in the weight room and on the competitive athletic field of play.
If you read last week’s article, you will know that the contraction is only part of the story. The velocity in the concentric and eccentric contractions will yield adaptations dependent upon high or low velocities. Go back and read that article for an even better understanding of how to measure each contraction for the desired adaptation to be ensured. When a strength coach understands the speed of contractions along with the various adaptations from the different muscular contractions, most any adaptation is possible. One thing is for sure, you will have an added ability to ensure proper adaptations for individual athletes.
As always, if you have any questions, email me at Travis@GymAware.com.
Watch the video presentation here:
Being a World Champion in powerlifting, Travis competed at a world-class level in Olympic weightlifting and has coached professional Olympic weightlifters alongside Don McCauley and Glenn Pendlay at Team MDUSA. Now Travis coaches the most successful weightlifting team in the USA.