Isometric Training on kBox: How to Get Stronger by Not Moving a Muscle

What are the 10 most important use cases for isometric training in sports performance? In this blog, Fredrik Correa, Exxentric CEO & former ice hockey coach, takes us through 10 use cases for isometrics in sports performance and explains why you as a coach should incorporate isometrics with the kBox in training your athletes. 

Why is Isometric Training important?

Isometrics can help you increase strength in certain angles, as well as sticking points. They are good for preparing muscle, joints, and soft tissue for higher loads. In sports, isometric training is known to improve sport-specific demands for athletes.

Moreover, isometrics can help desensitize the Golgi Tendon Organ for lower autoinhibitory responses in heavy lifting. They can also improve transition in dynamic eccentric-concentric actions.

10 great use cases for Isometrics in Sports Performance

  1. PAP (Post Activation Potentiation)
  2. Back after injury – controlled and less joint stress
  3. Target sport-specific angles
  4. Train more without adding fatigue
  5. Onboarding athletes with lower training age
  6. Take away the skill component
  7. Easy to reproduce
  8. Can be done both with and without a coach or assistant
  9. Great in warm-ups
  10. In-season training (combo of the ones above)

1. PAP (Post Activation Potentiation)

Maximizing Short-Term Power with PAP (Post Activation Potentiation): Potentation is the concept where you by a heavy stimulus can produce a more powerful action within a short time. Post Activation Potentiation, or PAP, is a stronger, more short-term effect over seconds and minutes but we also have PAPE (Post Activation Performance Enhancement) a weaker but longer-lasting effect that can last for about 15 minutes.

For example: a heavy squat before a high jump or a sprint start. The trick is to balance the stimulus (load, sets, reps) with the fatigue to get the most effect. The protocol is individual but using an isometric contraction is easy to standardize, easy to replicate, and easy to do for an athlete so unlock their potential with some flywheel potentiation work both in training and competition.

2. Back after injury

Accelerating Return to Sport Post-Injury with Low-Stress Isometrics: After injury, there is usually a long time until you can return to play in your sport, especially after surgery. Isometrics is a good invention that helps you start sooner and load from a low level and gradual progression.

It is safe since it is user-controlled and has very little risk due to the training not being very technically demanding. Earlier load in terms of days and weeks can save you months on the other end when it comes to return to play.

3. Target sport-specific angles

Enhancing Performance by Targeting Sport-Specific Joint Angles: Carrying, for example, a weight on your back for a whole repetition when you really just want to increase your strength around a sticking point or maybe in a sport-specific range of that exercise creates excessive fatigue.

With isometrics, you can target those angles exactly and safely with a minimal amount of work spent elsewhere in the range of motion.

4. Train more without adding fatigue

Boosting Training Volume without Increasing Fatigue: For the general public training more is a first-hand option since very few are training close to their capacity.

However, for athletes, very few on a top level are spending too little time on the sport and the improved performance and reduced injury risk is about training smarter and probably not more or harder.

Isometric training is an excellent way to target specific muscles, angles, and patterns without adding a lot of volume or work. In short, an easy and excellent way to target the workload to where you want the improvement.

5. Onboarding athletes with lower training age

Easing New Athletes into Strength Training with Accessible Isometrics: Many exercises, especially compound exercises, require some athleticism and also general strength to do well. Flywheel training already alleviates some of that need but there is still a big part of strength, control, and coordination needed and this is something that takes time.

Isometric training is more accessible and easier since the dynamic portion of the movement isn’t there but you can still target important muscles and motion with your training and improve strength. With strength also comes control so a good add-on tool to develop your younger athletes.

6. Take away the skill component

Simplifying Strength Gains by Eliminating the Skill Component: Most athletes don’t really have to be good at lifting, you just need to get them stronger so sometimes it makes sense to remove the skills component and focus on getting the strength stimuli they need.

If you are introducing a new exercise with a higher skill level, maybe add some isometrics to work through the range of motion to start building strength in a much easier way and take out the skill component. Or maybe use it as an add-on after your regular strength work.

7. Easy to replicate

Standardizing Training Intensity with Easy-to-Replicate Isometrics: Dynamic actions have a range of motion and a load and even if repeated well your daily max can change from cycle to cycle.

Isometrics are very easy to replicate in terms of angle and intensity and on top of that easy to scale when it comes to volume and intensity.

8. Can be done both with and without a coach or assistant

Enabling Independent Strength Training with or without Supervision: A lot of training of course doesn’t need supervision but a lot of heavier training does to make sure form and execution are ok and maybe help with a spot.

Isometrics is easy to do both with and without a spotter even with maximal loads. With the low demands on skill, it can easily be instructed and carried out by your athletes by themselves.

9. Great in warm-ups

Optimizing Warm-Ups with Targeted Isometric Exercises: A classic strength-specific warm-up is usually dynamic actions and gradually increased load until you reach your working sets. Isometrics is a great add-on and a nice way to loosen up in your warm-up.

In the kBox squat, for example, go down deep, catch the flywheel, and push up and side to side to loosen up your hips and active glutes and quads. Thank me later.

10. In-season training

Maintaining Peak Season Strength with Low-Impact In-Season Isometrics: A combination of multiple benefits but the short ramp up, the simple execution, and the low fatigue generated combined with the ability to target specific ranges makes it a great tool to target important ranges in your key exercises and a perfect in-season training tool to be used adjunct with your on-field practices or even after a game.


Incorporating isometric contractions into a comprehensive training program alongside dynamic exercises can help athletes achieve well-rounded improvements in strength, stability, endurance, and performance specific to their sport.

  • Strength Development: Isometric contractions can help in building strength, especially in specific joint angles relevant to sports movements. This is because isometric exercises target a specific joint angle, allowing athletes to strengthen positions critical to their sport.
  • Joint Stability: Isometric exercises engage the stabilizing muscles around joints, helping to improve joint stability and reduce the risk of injuries during dynamic movements common in sports.
  • Muscle Endurance: Isometric contractions can improve muscle endurance, as they require muscles to maintain tension for extended periods without movement. Enhanced endurance can be beneficial in sports that require sustained effort over time, such as long-distance running or cycling.
  • Plateau Breaking: Incorporating isometric training into a workout routine can help break through strength plateaus by challenging muscles in a different way than traditional concentric and eccentric contractions. This variation can stimulate muscle growth and adaptation.
  • Sport-Specific Application: Isometric exercises can be tailored to mimic specific movements or positions relevant to a particular sport. This specificity can help athletes improve performance in their chosen sport by strengthening muscles and joints in positions directly applicable to their athletic movements.
  • Improved Core Strength: Many isometric exercises engage the core muscles to stabilize the body during the contraction. This can lead to enhanced core strength, which is crucial for maintaining posture, and balance, and transferring force efficiently in sports movements.

… and more!

Exxentric's CEO Fredrik Correa

Fredrik Correa, M.D., CEO

Follow @fredrik_correa





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