In this era of “functional training”, the focus has shifted largely to movement, and we seem to have forgotten that muscles play a large role in movement. There is a gap between the use of heavy load or high velocity movement that should be considered before stepping into that kind of training. For example, people are learning to accelerate loads before learning to control them, like learning to do a thruster before learning to do a squat or overhead press.
To be efficient at moving weight, you have to learn how and when to recruit a muscle and integrate it into a complete movement pattern. Control and awareness come first when it comes to movement optimization and rehab, and
one of the most underrated tools for achieving this is the isometric contraction
There are many strategies when it comes to training methods, means and loading schemes. As a function of your goals and preferences, you will tend to prioritize and select certain kinds of elements in your training routine. As you have probably heard before, nobody reacts the same way to a training stimulus. So, something that works well for you will not necessarily provide the same outcome for another person. That being said, there are certain fundamentals that have to be integrated regardless of the individual to optimally and efficiently move weight.
Here are the many benefits of isometrics in training and rehab:
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ISOMETRICS FOR STRENGTH
Nervous system activation
Isometrics are a great tool when it comes to nervous system activation. A majority of studies have also concluded that human subjects can maximally or near maximally activate their muscles during maximal voluntary isometric contractions. A study by Babault et al., 2001 showed that voluntary muscle activation was 88.3% and 89.7% for maximal eccentric and concentric contractions, respectively, and 95.2% for maximal isometric contractions. Isometric contractions can activate more motor units and with less metabolic fatigue. In addition, there is a lower risk of injuries and it is easier to work on muscle-mind connection with the absence of movement provided by isometric contractions.
Furthermore, the near maximal effort provided by isometrics creates a post activation potentiation (PAP) effect. PAP is a theory that proposes that the contractile history of a muscle influences the mechanical performance of subsequent muscle contractions. The force exerted in subsequent sets is potentiated by the preceding isometric contractions. With greater intensity, we get greater nervous system adaptations and enhanced neural capacities.
Video 1 (Rack pull) – Overcoming isometric: You are pushing or pulling against an immovable resistance. Normally prescribed for a time under tension of 3 to 6 seconds, overcoming isometrics facilitate the activation of fast twitch fibers and increase neural activation. It is a great tool for your neural activation before your deadlift session. The similarity of the exercise facilitates the transfer to the actual movement by stimulating the same muscles and by recreating the same motor pattern.
Plateau buster
If you have difficulty switching from the eccentric to the concentric part of a movement, it is quite possible that you lack isometric strength. In fact, the principle of specificity stipulates that you develop what you train for. So, if you want to avoid strength leaks and be more efficient in utilizing the storage and release of energy to rapidly switch from the eccentric to concentric contraction, isometrics can be the answer. Working at a specific position in your range of motion will create structural adaptations that will help you maintain force production through the sticking point. The more time you spend at a specific range, the stronger you will be in this part of the movement. Strength gains are specific to the angle worked and can extend to 10-15 degrees above and below. Regardless of where your sticking point is in a particular movement, using isometrics at that specific point is a great tool to improve this.
Video 2 (Zercher cyclist squat) – Yielding Isometric: You are holding a weight in a specific position. By adding isometrics holds at a specific part of the range of motion, we provide a greater opportunity for our muscular and nervous system to create an adaptation resulting in better force production. In this video, the 3-2-1-0 tempo increases the time under tension at the bottom of the squat which teaches our body to optimally produce tension at the end of eccentric range and increases the stimulation of the quadriceps.
ISOMETRICS FOR HYPERTROPHY
Muscular activation
Yes, the muscle contraction is modulated by the nervous system, but if we are looking for an increase in muscle temperature, holding a load for a certain period of time can restrict blood flow into the muscle. When the tension is released, the muscle is filled with blood, which raises its temperature and increases its malleability. This in turn improves mind-muscle connection leading to better quality contractions, which is important to maximize muscle stimulation from a hypertrophy standpoint.
Video 3 (DB fly) – Yielding isometric: This type of yielding isometric is another option that can be used to improve mind-muscle connection increase blood flow to the muscle. In this video, we hold the point of maximal tension for predefined time to activate the pectoralis major. This could be used to prime the pec major before a bench pressing session, for example.
Pre/Post exhaustion
Pre/post exhaustion is principally used to exaggerate or amplify the fatigue on a muscle. It can be employed as a tool to work on mind-muscle connection with clients who have difficulty identifying and activating a muscle as well as feeling it contracting. It’s also a good way to increase time under tension and stimulate a large proportion of the muscle fibers. The more fatigue is created, the more motor units will be activated to maintain force production.
Video 4 (Band pull apart) – Iso-dynamic: Here we combine holds for time and dynamic movement in the same sequence. In this video, we use a pre-exhaustion to create awareness before adding dynamic movement on the muscles that are supposed to be activated.
Metabolic stress
The hypoxia created by the use of isometric contractions is an excellent stimulus to increase the release of IGF (Insulin-like growth factor) resulting in protein synthesis and mTOR activation. With the absence of oxygen, the anaerobic energy pathway will deplete a lot more your muscle glycogen stock. Your body will adapt to this by increasing its capacity to store glucose resulting in a bigger muscle (sarcoplasmic hypertrophy). For every gram of glucose stored, 3g of water will combine to it. So, yes, you will look bigger and you will have more energy resource to tolerate training volume.
Video 5 (Landmine press) – Multi-hold pump: Here we add pauses on the eccentric and/or concentric phase to increase the time under tension. The more time under tension, the greater the hypoxia effect will be. Greater hypoxia will have more impact on local and systemic hormone production. By adding pauses on the eccentric phase, we increase time under tension and create a metabolic stress on fast twitch fibers resulting in a greater potential for hypertrophy.
REHABILITATION
Creating stability
Isometric contractions allow you to work with loads that are lighter than the ones you normally use and still have the same level of fatigue that you normally feel. In fact, using lighter loads will help you to maintain a better control on your execution and your motor patterns.
In addition, when we talk about instability there is also a concept that is often neglected. The more a movement pattern is unstable, the higher the chances are of compensation and the harder that makes it to correct. The concentric and eccentric actions used in a movement can be a source on instability in many ways. Using isometrics helps you to focus more easily on muscle activation and joint stabilization. The static positioning of an isometric action helps mitigate movement error or rep to rep variability.
Video 6 (External rotation control) – End range isometric holds: The use of repeated isometric holds at end range of motion is a great way to improve movement control and awareness. It can be quite useful in cases of hypermobility. To learn more about managing hypermobility, take a look at our free 2-hour Masterclass on the topic!
Analgesic effects
Isometric contractions have also been shown to have hypoalgesic effects, although the optimal dose of exercise that is needed to produce hypoalgesia is not well-documented. In their meta-analysis, Naugle, Fillingim, and Riley (2012) found that isometric exercise reduced pain perception across all pain stimuli (experimentally-induced noxious stimuli) and exercise protocols (with the exception of one study included in the metanalysis).
Some studies have shown that long-duration, low-intensity (25% of MVC) contractions have the greatest analgesic effect, however, contractions of up to 80% have shown analgesic effects. Other observations show that the amplitude and duration of the contraction do alter pain perception, with 25% of MVC contractions to task failure leading to significant analgesic effects, whereas contractions at 25% of MVC for 2 minutes do not. This finding suggests that the recruitment of high threshold motor units is necessary for the analgesic effect to emerge, and that increasing force amplitude in acute tasks is not effective in reducing pain perception, but task failure is
However, there is some evidence to suggest that the recruitment of high threshold motor units is not necessary for analgesic effects to emerge. For instance, reductions in pain perception have been demonstrated during and following shorter contractions in the range of 15 to 120s.
Since there is no consensus on optimal dosage of isometric exercise for hypoalgesia, we advocate individualization based on the limiting factor:
- If there is still residual pain that limits the intensity of contraction that is possible, opt for low-intensity, long-duration isometrics
- If pain limits the individual from holding the contraction for a longer duration, opt for higher intensity, lower-duration isometrics
- If the individual is deconditioned, for example following a period of immobilization or disuse, they may not be able to produce high force nor hold for long durations. Opt for as hard as possible as long as possible
There really is no right or wrong, as long as you have a reason for the parameters you are applying.
A POWERFUL TOOL
Isometrics are often neglected in favor of other types of contraction. However, there is a time and place to use them like every other tool. They are well-suited to work on mind-muscle connection and to reinforce the motor pattern and posture related to a specific movement. They can be also useful for strength, hypertrophy work and rehab.
The use of heavy load or high velocity movement should be preceded by movement awareness and control, something that isometrics can significantly help improve. We need to remember that movement is produced by muscles and that understanding and feeling how to use them will provide you with the foundation for the development of other strength qualities.
While they are a simple tool, isometrics provide significant results, with the added advantage of being accessible for all populations. As such, integrating isometrics into your programming is of great importance. Curious about periodization using isometrics to help you build your basics and lasting strength? Stay tuned, we have an upcoming article on just that!
Article by: Pierre-Luc Dubé, B.Sc., kinesiologist
Pierre-Luc’s love for performance and athletic development comes from his background as an athlete himself. Holding a bachelor’s degree in kinesiology from Laval University, he works with clients and athletes who aim to reach new performance levels. His approach is centered around the meticulous periodization of training variables to create a more effective progression and greater adaptations.
Co-authored by:
Mai-Linh Dovan M.SC., CAT(C)
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