This post explains the science underpinning isometric strength training and four key reasons why this has become such a popular training approach in sports science today.
Isometric exercises, where muscles exert force without changing length, have surged in popularity in recent times. They have long been applied in research and practice but now seem more popular than ever. They are used widely for both isometric training and testing. But why have they gained such traction?
Introduction to Isometric Training
Isometric exercises involve static muscle contractions where the muscle exerts force without changing its length. These exercises can be integrated into various training regimens and are known for their significant benefits across diverse populations. To understand their efficacy, it’s essential to grasp the force-velocity relationship, foundational to muscle actions.
In concentric muscle actions, increased velocity results in decreased force, whereas eccentric contractions exhibit the opposite pattern with negative velocities. At zero velocity, the force generated is due to isometric contractions, which require static muscle activity. Though technically, there is muscle shortening during an isometric contraction because of tendon creep.
Isometric actions can be classified into two primary types:
Pushing Isometric Muscle Action (PIMA):
Also referred to as overcoming isometrics, these occur when a muscle exerts force against an immovable object, like an overloaded barbell. The muscle attempts a concentric action but the joint does not move as the load is too heavy to overcome.
Holding Isometric Muscle Action (HIMA):
Known as yielding isometrics, these involve the muscle resisting flexion or extension by applying an opposing force equal to the held mass, thereby preventing joint motion and muscle lengthening.
Reason 1: Effectiveness
Isometric training has proven effective in enhancing strength, hypertrophy, rate of force development, and tendon stiffness. Research by Danny Lum, such as this Randomized Controlled Trial in kayaking, and others indicates isometric exercises can lead to notable strength gains, potentially more efficiently than purely dynamic exercises. Watch the video above to learn more about this research.
Reason 2: Safety
Isometric exercises are self-limiting, making them particularly beneficial for individuals with joint issues or those recovering from injuries. Since these exercises don’t involve joint movement, they can be introduced early in the rehabilitation process to prevent atrophy and build strength within safe ranges.
In the video above, I discuss a hamstring rehab case study from Nicol van Dyk’s in VALD's free Practitioner Guide to Isometrics, which demonstrates how isometric training and testing might be safely incorporated into early recovery stages.
Reason 3: Versatility
Isometric exercises require minimal equipment and can be performed almost anywhere, making them practical for different settings. Their versatility allows athletes and individuals to easily integrate them into their routines, whether in a clinic, on the road, or even at home, without needing access to a gym.
The figure below, also taken from VALD's Guide, demonstrates the versatility in isometric training approaches. Of course, knowing when and how to programme each of these depends on the context of the individual, their injury history, and their training goals.
Reason 4: Objectivity via Technology
Technological advances have enabled the quantification and tracking of isometric exercises, making them more objective and practical. Utilising devices like force plates or dynamometers, athletes can monitor various metrics such as force output, rate of force development, and asymmetries over time.
This data-driven approach facilitates precise and objective assessments of performance, further enhancing the appeal of isometrics. We have demonstrated these approaches throughout my YouTube athlete testing series in collaboration with VALD.
Final Thoughts
The resurgence in the popularity of isometric exercises can be attributed to their effectiveness, safety, versatility, and the objective insights provided by technology. As our understanding of these exercises continues to grow, their application in sports science and rehabilitation will likely expand, benefiting athletes and practitioners alike.
For more information, download VALD's free eBook: Practitioner's Guide to Isometrics here.
Frequently Asked Questions (FAQs) on Isometric Exercises
What are isometric exercises?
Isometric exercises involve static muscle contractions where the muscle exerts force without changing its length. Although technically, the muscle can potentially shorten due to tendon creep.
How do isometric exercises differ from concentric and eccentric exercises?
Concentric exercises involve muscle shortening while generating force, and eccentric exercises involve muscle lengthening under tension. Isometric exercises, on the other hand, involve generating force without muscle length changes.
Are isometric exercises safe for injured individuals?
Yes, isometric exercises are particularly safe and beneficial for those with joint issues or recovering from injuries as they don’t involve movement of the joints and can be introduced early in the rehab process. The specifics of how they are introduced are, as ever, dependent on the injury and the specific individual case.
Can isometric exercises improve muscle strength and hypertrophy?
Research shows that isometric exercises can lead to gains in strength, hypertrophy, rate of force development, and tendon stiffness. I explore some of this research in more detail in the video above.
How can technology aid in isometric training?
Technological advancements like force plates and dynamometers enable precise quantification and tracking of metrics such as force output and rate of force development, making isometric training more objective. We often refer to this approach as 'training as testing'.
This article is support by VALD Performance. For more information, about their technology, visit their website.
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