Before diving right into this topic, there are some general pieces of advice that should be known. Any exercise that you may perform is always going to yield greater benefits when performed appropriately with proper technique and proper programming to ensure that the physiological stress being applied to the body is not one that exceeds the body’s ability to recover from. Understanding proper mechanics, programming principles and recovery methods is always advisable to get the best results and minimize the risk of injury. This is a very in depth and widely studied topic, but this is a breakdown of general knowledge regarding muscle contractions.
When it comes down to exercising there are three basic forms of muscular contractions that can be performed during any movement.
These three contractions are:
These three contractions are:
This type of contraction is expressed during the actual lifting of a weight, when the target muscle(s) are shortening against resistance and force is produced.
This type of contraction is expressed during the lowering phase of an exercise when the target muscles are lengthening, and the muscle(s) must resist gravity or the external load.
This type of contraction requires a static, no movement, hold in which there is no change in muscle length or joint angle.
Each one of these three contractions play an important role and have a specific application for building strength and muscle when being implemented into a resistance training program. Neglecting any one of these 3 types of contractions is going to have an individual falling short of their maximum potential for producing physiological adaptations in their body.
During a concentric contraction, the muscle must produce enough force to be able to move the external force. If the muscle is unable to produce enough force, the muscle will not shorten, and the resistance will not move. This type of contraction is important for producing muscle growth but performing only concentric contractions will produce significant less growth response by the muscle than if performed in conjunction with its antagonist contraction type – the eccentric. As the force required to move an object increases, the greater muscle fiber activation will be triggered to move the object.
This response from the central nervous system (CSN) will produce the greatest effects for developing strength. Assuming that proper execution is performed and depending on the threshold of muscle fibers being activated, a concentric contraction can be repeatedly performed up until a point where the force production becomes insufficient to sustain shortening of the muscle at which point an isometric or an eccentric contraction would begin or the load would be dropped.
An eccentric contraction occurs in a few different circumstances. As mentioned above, when the load becomes greater than the force production created through the concentric, an eccentric begins as the muscle contracts during the lengthening of a muscle or muscle groups. The deceleration of the load as the muscle returns to its original positions helps the protect the involved joints. This type of contraction plays an enormous role is injury prevention, rehabilitation, strength development and building muscle. Resistance training programs that apply both concentric and eccentric efforts throughout display much greater results for those looking to improve their body composition. A muscle being put under an eccentric load is capable of withstanding upwards of 40% greater loads than that possible to successful perform a concentric exercise with. This ability to overload the eccentric portion of an exercise, particularly if performed correctly, can substantially help to recruit more total muscle fiber activation in the muscle leading to greater strength gains then possible with concentric focussed training only. Although the body is capable of withstanding more load, if this is not a style of training you have ever experienced, it is advisable to even lower the weight to begin and work through the eccentric component of the movement with greater control by slowing down the tempo. As the body begins to adapt to this style of training then beginning to progressively load this movement is appropriate. This training style can play a tremendous role is preventing injury as well as injury rehab. Eccentric training is associated with greater fast twitch muscle fiber activation. This can have great carry over into certain applications of training when it comes to performance-based attributes such as strength, speed, agility and explosiveness.
Lower Cross Syndrome
The third type of contraction is an isometric. This can be seen in cases where an individual attempts to lift something that is too heavy. The muscles will produce maximal force, but the load will not move. This can also be seen when any movement is paused to create a static hold. Maximal effort is required to sustain a static position, as in the plank, or intentionally pausing at the bottom of a squat. Isometrics may not hold the same appeal level as concentric or eccentric training but yield great benefits when applied. This style of training allows for maximal force production in the muscle without any movement of the joint(s). Here are a few of the benefits to training with isometrics:
1. Safe on joints and other structures of the body
2. Low impact and safe to perform
3. Can be performed anywhere with little to no equipment
4. Reduce injuries or rehab application
5. Improved range of motions / flexibility
6. Improvements in body composition
7. Improved ability to brace + breathe
8. Overcoming plateaus
9. Improved central nervous system (CNS) response
Isometrics have been used in different modalities for decades. From the early days of bodybuilding when posing was developed, to yoga practise when a static position is held to increase strength and stability.
When it comes to the best application of these within a fitness program, as with anything in the fitness realm, it depends on the individual and their intent. But for discussion sake, let’s look at a healthy individual who has some exercise experience under their belt and looking to improve body composition and be healthy. The majority of what a normal workout would look like for the average person would be with the primary focus on the concentric phase while lifting the weight. When the goal is to improve body composition, an easy way to modify your workout is to simply put equal or more emphasis towards controlling the eccentric aspect of your exercises. This will elicit a much stronger response from the muscles which will lead to muscle development and strength, while also strengthening tendons and ligaments surrounding the joints. I always suggest following a 4-1-2-1 tempo scheme, and all this means is that you are controlling your eccentric for 4 seconds, a 1 second pause at the bottom, 2 seconds to lift the weight, and a 1 second squeeze at the top. These values can change but normally maintaining an eccentric that is double the length of the concentric will yield good results.
As you practise incorporating a slow eccentric into your exercises, you can progress this by continuing to slow the tempo down or gradually increasing the load. Intentionally lengthening the contractile time of your concentric or eccentric will dramatically change the way your workouts feel and the response you will achieve. Timed concentric exercises are a very uncommon approach to lifting, perhaps due to the imposed difficulty to do so. Someone who is a more advanced lifter may find some benefit behind playing around with this technique, increase the concentric phase to 6-8 seconds of controlled shortening without pausing throughout the movement. Developing overall better control of your movements will guarantee you increase strength, muscle growth and joint stability.
When it comes to applying isometrics to your workout, there is a bit more variable as to when and how to do so. For someone who has decreased range of motion, joint limitations, recovering from injury or perhaps just struggling to engage muscles during compound movements – adding isometrics in at the start of the workout is ideal. This could also be an active recovery day or an entire workout if being used for injury rehab or for use with elderly. Performing these static position holds against an immovable barrier or a therapy band will allow for activation and strength development without applying stress on the joints. The length of an isometric may vary and will increase as you practise more and more. Starting off with a 5-10 second hold and performing 2-3 sets will allow for the benefits. In some applications such as postural correction or in a rehab scenario, performing 1-2 sets at several internals throughout the day would be the best approach
Isometric can also help to establish better body control and awareness. Being able to concentrate on the desired muscle and actively tense it whether exercising or not can be a very practical skill to have. Isometrics are an excellent way to break through plateaus as they help to send a strong signal to the CNS to respond. The CNS responds to repeated isometric stress by ramping up motor unit response in the muscles which are responsible for the signalling of strength and muscle development. This effect is like replacing a car’s 4-cylinder engine with a turbo. The output ability exponentially increases. As made popular by the bodybuilding community, a post-exercise “flex” or concentrated squeeze can help improve braced-breathing and blood flow to this area after having already worked it to stimulate growth.
Isometrics can be done by anyone, anywhere, with no gym equipment. Most can be performed by simply concentrating on a muscle group and flexing it (i.e. Contracting the abdominals while driving). This is a great technique to implement when on away on vacation, on the road with work, or simply stuck at home.
As mentioned before, this builds great connection to the muscles too which will allow for great gains with more heavy compound movements if you know how to actively engage.
As mentioned at the beginning, this topic has been widely researched and can be quite complex. Understanding human anatomy/physiology is something that will always be under studies to even come close to understanding the complexity of it all. However, having a general understanding of the different types of contractions, how to perform and how to implement is a good place to start. Play around with these suggestions in your workout and pay close attention to what happens. Figure out what feels the best for you and learn to implement that as a normal part of your routine.