Trainer’s Toolbox: The Kamagon Ball

By Keli Roberts

When it comes to introducing new products, the fitness industry appears to be a limitless supply of creativity and ingenuity, applying new materials and elements to create functional and highly effective workouts. From iron to sand to water, a wide range of products are now available, each utilizing these elements in unique ways. One of the latest offerings is the Kamagon

Ball®, which is a hybrid of a medicine ball and a kettlebell, but with two handles, a forgiving plastic surface and a dynamic shifting load of water inside the ball.

The Kamagon Ball was designed to facilitate total-body, integrated movement that effectively and efficiently recruits the core musculature, explains Mark Reed, vice president of Kamagon Fitness. Because it is filled with water, the Kamagon Ball is a destabilized weight, which means it is the ball itself is the point of instability (as opposed to performing strength or balance exercises on an unstable surface, for example). In fact, compared to an equal amount of static weight, the water movement within the ball and the weight/mass of the ball requires greater recruitment of the muscle fibers when performing the same number of repetitions. So, rather than having clients stand on an unstable surface and manipulate a stable object with their hands, training with the Kamagon Ball involves having clients stand on a stable surface and manipulate an unstable object. The very nature of this type of instability has a great potential for carryover into activities of daily living and sports performance.

The ball can be held like a medicine ball, or with two hands on one handle (like a kettlebell), one hand on each handle or even one hand on the ball. This allows for creativity in the exercise selection. The water motions can vary from powerful to subtle, depending on the exercise and the needs of the user. Here are some of the features that make the Kamagon unique:


Hydro-Inertia® is the utilization of water within the Kamagon Ball to create an unstable resistance and moving mass within a mass, which in turn enhances core musculature recruitment. Hydro-Inertia can be maximized with powerful, explosive movement sequences, plyometric exercise, or even slow, controlled, balance-oriented movements that require refined motor skills.

Dual U-shaped Handles

During both sports and activities of daily living, the objects being manipulated typically have a center of mass outside the hand (e.g., golf club, grocery bags). Dumbbells held in the palm of the hand keep the center of mass of the dumbbell closer to the hand, relatively proximal to the joint. By contrast, the Kamagon Ball’s two U-shaped handles create a center of mass that is away from the hand, thus providing a unique and functional challenge to the nervous system.

Center of Gravity Displacement

Center of gravity (COG) is the balance point of an object, a body or a unified system (a person lifting a Kamagon Ball, for example). COG is the point of an object where all forces add up to 0. The COG for a standing adult human is the midpelvic cavity, between the symphysis pubis and the umbilicus.

When COG is in motion, such as when lifting the Kamagon Ball, the COG of the ball is dynamic—it changes through the motion due to the Hydro-Inertia. Therefore, the exerciser’s COG must change with it. Most Kamagon Ball exercises are loaded on one side only, and this asymmetrical dynamic load shifts the COG and creates a greater degree of instability, requiring an increased amount of core stabilization and balance.

Complex Leverage System

Leverage is the application of force through rigid objects (levers). A system of levers has a tendency to produce rotational force or torque. The human body is a system of levers (bones) and joints (fulcrums) and soft tissue attachments that enable us to manipulate our environment to achieve goal acquisition.

The human body is comprised of predominantly third-class levers, putting us at a biomechanical disadvantage (Figure 1). Humans have a shorter force arm than resistance arm because the tendons insert closer to the joint and the load we manipulate is concentrated farther from the joint. Therefore, the human body favors speed, dexterity and mobility at the expense of force output capacity.

Because many of the Kamagon Ball exercises are performed with momentum and speed (suitable for a third-class lever system), this results in improved exercise efficiency in sports and life performance. The nervous system is the direct link by which muscles are recruited for the desired action, and because the Kamagon Ball trains integrated movement (as opposed to an isolated individual muscle group), improvements in function are possible.