In the business of fitness, we as professionals are always looking for fun, effective, and affordable tools to give our clients the best workouts possible. When it comes to searching for these tools, there is no shortage of options, so we must choose wisely and select tools that have solid research and methodology behind them. If you’ve been keeping up with fitness trends you know that water is all the rage. There are multiple ways to use water for low-impact cardio such as water aerobics, aqua cycling or WaterRowers. Get excited because now you can introduce your clients to water-based resistance training using Hydro-Inertia®!

What is Hydro-Inertia® you ask? Great question. Simply put, Hydro-Inertia® is the utilization of water to create an unstable resistance and moving mass within a mass. Hydro-Inertia® drives the methodology behind the Surge® and the Kamagon® Ball. These two pieces of equipment are emerging in the fitness industry and becoming the breakout stars of the season. Understanding Hydro-Inertia® will enable you to more efficiently and effectively incorporate a new level of training into your clients’ workouts.

So, let’s break it down. Inertia means that an object will remain in motion at constant speed and in a straight line unless acted on by an outside force. The more mass an object has, the harder it is to move or stop moving. This means that when working with the Surge® or the Kamagon® Ball, you must use force to move the object and use an equal and opposite force to stop or change direction of the movement. To make things a bit harder, we add water, hence the “hydro” in Hydro-Inertia®. With water inside the equipment, you must also work against the inherent force of the water which is also moving, stopping and starting at its own speed within the object. Hydro-Inertia® challenges your body to counter instability from the top down, perform full range of motion movements that engage the entire body, and to mimic real life functional movement patterns.

Both the Surge® and Kamagon® Ball can be incorporated into a workout program as a form of strength or cardio depending on the nature of the move, the amount of water resistance, and the duration of the exercise.

Let’s look at the Surge® 3-Point Strike. As you shift your weight slightly forward, the Surge® is quickly striking back and forth with a crashing water action. Your body is not only working with the weight of the moving Surge®, but also working to stabilize and resist the backwards force the water creates.


Similarly, during a Kamagon® Ball swing, you are working to move a mass (the Kamagon® Ball) and working against the force of the moving water inside. The instability of the moving water creates stabilization and movement control challenges.


The Surge® and Kamagon® Ball are smart additions to your fitness tool box. Water can easily be added or removed for transport or to change the weight from client to client. Their compact, sleek design is ideal for small spaces or minimal storage and maybe best of all, they won’t break the bank. Be sure to follow Hedstrom Fitness on Instagram and Facebook for more on Hydro-Inertia® and ways to incorporate the Surge® and Kamagon® Ball into your classes or training sessions.


Alison Smith has a Masters degree in Kinesiology and works with athletes, college students, kids, older adults, and everything in between. In additional to working as a Hedstrom Fitness National Master Trainer, Alison owns EnergyX Fitness in San Antonio, Texas.